Denial codes are the standard codes a payer puts on a remittance (835/ERA or paper EOB) to explain why a claim or service line wasn’t paid in full. Each adjustment combines three parts:
- a group code, which says who is responsible;
- a Claim Adjustment Reason Code, or CARC, which says why;
- usually one or more Remittance Advice Remark Codes, or RARCs, which say exactly what.
X12 maintains the official CARC, RARC and group code lists, and CMS notes that the CARC list is updated three times a year (Medicare Claims Processing Manual, Ch. 22, §60.2).
Every guide in this library quotes the official X12 description word for word, explains it in plain English, and links its sources. New to remittances? Start with what medical billing is and how the claim cycle works. For a data-backed overview of why claims fail, see most common claim denial reasons.
New to remittance codes? Start with our CARC & RARC codes guide — how group codes, reason codes and remark codes fit together on an 835/ERA.
Key Takeaways – Read every adjustment as group code + CARC + RARC: who pays, why, and what exactly. – CO amounts are generally a provider write-off; PR amounts may be billed to the patient. – A Medicare claim returned as unprocessable has no appeal rights. Fix it and resubmit. – Use the lookup table below to find the official X12 wording and the full guide for each code.
Written by Manikandan, a revenue cycle management specialist with more than 10 years of US medical billing experience. Last reviewed: 3 October 2026, against the X12 CARC list dated 11/1/2025 and the RARC list dated 7/1/2026. How we check sources: editorial policy.
How to read a denial: group code + CARC + RARC
Take the remittance line CO-16 + N290:
- CO is the group code. It tells you who carries the amount.
- 16 is the CARC. It tells you why: the claim “lacks information or has submission/billing error(s).”
- N290 is the RARC. It tells you what: “Missing/incomplete/invalid rendering provider primary identifier.”
So the fix is to correct the rendering provider NPI and resubmit. The patient isn’t billed.
Group codes: who is responsible
The current X12 group code list has four codes:
| Group code | X12 name | What it means for you |
|---|---|---|
| CO | Contractual Obligation | CMS: adjustments that are “generally… considered a write off for the provider and are not billed to the patient.” |
| PR | Patient Responsibility | CMS: an amount that “may be billed to the patient or insured,” such as a deductible, coinsurance or copay. |
| OA | Other Adjustment | CMS: used “when no other group code applies.” |
| PI | Payor Initiated Reduction | A reduction initiated by the payer. X12 lists it, but CMS lists only CO, OA and PR as valid on Medicare remittances, so PI appears on non-Medicare remittances. |
CMS quotes are from the Medicare Claims Processing Manual, Ch. 22, §60.1.
CARCs: the reason
A CARC is a number or a letter-number combination (for example 16, 45 or B9) that explains one adjustment amount. One CARC explains each adjustment amount, and a single line can carry several adjustments. For the full walkthrough of CARCs, RARCs and group codes, see CARC & RARC codes.
RARCs: the detail
RARCs start with M, MA or N. Some are “Alert:” codes that give information only. Others pinpoint the exact error. Some CARCs, including 16, 96, 252 and A1, require at least one remark code that isn’t an Alert, so always read the RARC before you act.
CARC vs RARC at a glance
A CARC tells you why an amount was adjusted. A RARC adds the detail you need to fix it. Use this side-by-side view when you read an 835 or EOB line.
| Question | CARC (reason code) | RARC (remark code) |
|---|---|---|
| What does it answer? | Why the amount was adjusted | What exactly is wrong, or an FYI |
| What does it look like? | A number or letter-number, such as 16, 45 or B9 | Starts with M, MA or N, such as N290 or MA130 |
| How many per adjustment? | One per adjustment amount | Zero, one or more |
| What is it paired with? | Always a group code: CO, PR, OA or PI | The CARC it explains |
| Is it ever required? | Yes, on every adjustment | Yes for some CARCs, such as 16, 96, 252 and A1 |
| Who keeps the list? | X12 | X12 |
So for CO-16 + N290, the group code says the provider carries it, the CARC says the claim lacks information, and the RARC says the rendering NPI is the problem.
Reviewed by Manikandan J, CPC, CRCR on October 14, 2026. The group code, CARC and RARC notes on this page were checked against the X12 code lists and the CMS manuals linked here.
Rejection, unprocessable claim or denial?
- Rejection: the clearinghouse or payer stops the claim at the front end. It never reaches adjudication.
- Returned as unprocessable (Medicare): the claim had incomplete or invalid information. CMS says such a claim “is not denied, and, as such, is not afforded appeal rights.” You correct it and resubmit (CMS IOM 100-04, Ch. 1, §80.3.1).
- Denial: a payment decision. Denials can be appealed.
Denial code lookup table
Search by code (for example “co16”, “CO-16” or “16”) or by keyword, and filter by category or group code.
| Code | Type | Group code(s) | Official X12 description (verbatim; usage notes omitted) | In plain English | Category | Guide |
|---|---|---|---|---|---|---|
| CO-16 | CARC | CO | Claim/service lacks information or has submission/billing error(s). | Claim has missing, incomplete or invalid data. Check the remark code. | Missing / invalid information | CO-16 guide |
| N290 | RARC | n/a | Missing/incomplete/invalid rendering provider primary identifier. | Rendering provider NPI missing or invalid. | Missing / invalid information | N290 guide |
| MA130 | RARC | n/a | Your claim contains incomplete and/or invalid information, and no appeal rights are afforded because the claim is unprocessable. Please submit a new claim with the complete/correct information. | Unprocessable claim. Fix it and send a new claim; no appeal. | Missing / invalid information | MA130 guide |
| M51 | RARC | n/a | Missing/incomplete/invalid procedure code(s). | Procedure code missing or invalid. | Missing / invalid information | M51 guide |
| CO-252 | CARC | CO | An attachment/other documentation is required to adjudicate this claim/service. At least one Remark Code must be provided (may be comprised of either the NCPDP Reject Reason Code, or Remittance Advice Remark Code that is not an ALERT). | Payer needs an attachment or documentation. | Missing / invalid information | CO-252 guide |
| CO-26 | CARC | CO | Expenses incurred prior to coverage. | Service date is before coverage started. | Eligibility & coverage | CO-26 guide |
| CO-27 | CARC | CO | Expenses incurred after coverage terminated. | Service date is after coverage ended. | Eligibility & coverage | CO-27 guide |
| PR-200 | CARC | PR | Expenses incurred during lapse in coverage | Date of service fell in a gap in coverage and the amount is patient responsibility; verify eligibility for that date first. | Eligibility & coverage | PR-200 guide |
| CO-31 | CARC | CO / PR | Patient cannot be identified as our insured. | Payer can’t match the patient to a member. Check the ID and name. | Eligibility & coverage | CO-31 guide |
| CO-24 | CARC | CO | Charges are covered under a capitation agreement/managed care plan. | Covered by a capitation or managed care (e.g., Medicare Advantage) plan. | Eligibility & coverage | CO-24 guide |
| CO-109 | CARC | CO | Claim/service not covered by this payer/contractor. You must send the claim/service to the correct payer/contractor. | Wrong payer or contractor. Send it to the correct one. | Eligibility & coverage | CO-109 guide |
| CO-256 | CARC | CO | Service not payable per managed care contract. | Contract has no payable line for the service as billed; check the fee schedule, modifier and provider record. | Eligibility & coverage | CO-256 guide |
| CO-B9 | CARC | CO | Patient is enrolled in a Hospice. | Patient is enrolled in hospice. | Eligibility & coverage | CO-B9 guide |
| CO-22 | CARC | CO | This care may be covered by another payer per coordination of benefits. | Another payer may be primary (coordination of benefits). | Coordination of benefits | CO-22 guide |
| PR-22 | CARC | PR | This care may be covered by another payer per coordination of benefits. | COB reason filed as patient responsibility: verify the primary payer before billing the patient. | Coordination of benefits | PR-22 guide |
| CO-197 | CARC | CO | Precertification/authorization/notification/pre-treatment absent. | Required prior authorization or notification was missing. | Authorization | CO-197 guide · UHC, Cigna & Aetna |
| CO-4 | CARC | CO | The procedure code is inconsistent with the modifier used. | Modifier doesn’t fit the procedure code, or a required modifier is missing. | Coding, modifiers & bundling | CO-4 denial code guide |
| CO-97 | CARC | CO | The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated. | Service is bundled into another service already processed. | Coding, modifiers & bundling | CO-97 guide |
| CO-236 | CARC | CO | This procedure or procedure/modifier combination is not compatible with another procedure or procedure/modifier combination provided on the same day according to the National Correct Coding Initiative or workers compensation state regulations/ fee schedule requirements. | Procedure pair not allowed together under NCCI. | Coding, modifiers & bundling | CO-236 guide |
| CO-B15 | CARC | CO | This service/procedure requires that a qualifying service/procedure be received and covered. The qualifying other service/procedure has not been received/adjudicated. | The service depends on another (qualifying) service that hasn’t been billed, paid or processed. | Coding, modifiers & bundling | CO-B15 guide |
| CO-11 | CARC | CO | The diagnosis is inconsistent with the procedure. | Diagnosis doesn’t support the procedure. | Coding, modifiers & bundling | Coming soon |
| CO-50 | CARC | CO | These are non-covered services because this is not deemed a ‘medical necessity’ by the payer. | Payer says the service wasn’t medically necessary. | Medical necessity & non-covered | CO-50 guide |
| CO-96 | CARC | CO / PR | Non-covered charge(s). At least one Remark Code must be provided (may be comprised of either the NCPDP Reject Reason Code, or Remittance Advice Remark Code that is not an ALERT.) | Non-covered charge. Check the remark code. | Medical necessity & non-covered | CO-96 denial code guide |
| PR-204 | CARC | PR / CO | This service/equipment/drug is not covered under the patient’s current benefit plan | The patient’s plan doesn’t include this service, item or drug. | Medical necessity & non-covered | PR-204 guide |
| PR-49 | CARC | PR | This is a non-covered service because it is a routine/preventive exam or a diagnostic/screening procedure done in conjunction with a routine/preventive exam. | Routine or preventive exam (or a test done with one) that isn’t covered. | Medical necessity & non-covered | PR-49 guide |
| CO-307 | CARC | CO | Medicare Maximum Fair Price Standard Default Refund Amount Adjustment. | Medicare Drug Price Negotiation MFP refund/pricing adjustment (not a coverage denial). | Payment adjustments | CO-307 guide |
| CO-60 | CARC | CO | Charges for outpatient services are not covered when performed within a period of time prior to or after inpatient services. | Outpatient charges fell inside the inpatient payment window. | Bundling / window | CO-60 guide |
| CO-39 | CARC | CO | Services denied at the time authorization/pre-certification was requested. | Auth/pre-cert was requested and denied (not the same as missing auth). | Authorization | CO-39 guide |
| CO-70 | CARC | CO | Cost outlier – Adjustment to compensate for additional costs. | Cost-outlier payment adjustment for high-cost cases. | Payment adjustments | CO-70 guide |
| CO-151 | CARC | CO | Payment adjusted because the payer deems the information submitted does not support this many/frequency of services. | Payer says documentation doesn’t support this many services or units. | Frequency / units | CO-151 guide |
| OA-23 | CARC | OA | The impact of prior payer(s) adjudication including payments and/or adjustments. (Use only with Group Code OA) | COB reporting of prior payer payment/adjustments (not a coverage denial). | Coordination of benefits | OA-23 guide |
| CO-23 | CARC | CO | The impact of prior payer(s) adjudication including payments and/or adjustments. (Use only with Group Code OA) | Prior payer impact filed under CO instead of OA: do not auto write-off. | Coordination of benefits | CO-23 guide |
| CO-234 | CARC | CO | This procedure is not paid separately. At least one Remark Code must be provided (may be comprised of either the NCPDP Reject Reason Code, or Remittance Advice Remark Code that is not an ALERT.) | Procedure not paid separately; remark code required (bundling/packaging). | Coding, modifiers & bundling | CO-234 guide |
| CO-253 | CARC | CO | Sequestration – reduction in federal payment | Medicare sequestration cut (2% of the Medicare FFS payment, per Noridian); write-off, not a service denial. | Payment adjustments | CO-253 guide |
| PR-119 / CO-119 | CARC | PR / CO | Benefit maximum for this time period or occurrence has been reached. | Plan benefit max hit for the period or occurrence; PR may bill patient, CO usually write-off. | Frequency / units | PR-119 guide |
| PR-227 / CO-227 | CARC | PR / CO | Information requested from the patient/insured/responsible party was not provided or was insufficient/incomplete. At least one Remark Code must be provided (may be comprised of either the NCPDP Reject Reason Code, or Remittance Advice Remark Code that is not an ALERT.) | Patient/insured info missing or incomplete; remark required. Different from CO-226 (provider-side info). | Missing or invalid claim information | PR-227 guide |
| N381 | RARC | — | Alert: Consult our contractual agreement for restrictions/billing/payment information related to these charges. | Contractual alert remark; often pairs with CO-45. Read the contract/fee schedule. | Contractual & patient responsibility | N381 guide |
| PR-242 / CO-242 | CARC | PR / CO | Services not provided by network/primary care providers. | Rendering provider not network/PCP; related 243 is not authorized by network/PCP. | Provider enrollment | PR-242 guide |
| CO-A1 | CARC | CO | Claim/Service denied. At least one Remark Code must be provided (may be comprised of either the NCPDP Reject Reason Code, or Remittance Advice Remark Code that is not an ALERT.) Usage: Use this code only when a more specific Claim Adjustment Reason Code is not available. | Catch-all denial requiring a remark; use only when no more specific CARC fits. | Missing or invalid claim information | CO-A1 guide |
| CO-59 | CARC | CO | Processed based on multiple or concurrent procedure rules. (For example multiple surgery or diagnostic imaging, concurrent anesthesia.) | Multiple/concurrent procedure pricing (e.g. multiple surgery / MPPR); check 835 policy REF. | Coding, modifiers & bundling | CO-59 guide |
| CO-19 | CARC | CO | This is a work-related injury/illness and thus the liability of the Worker’s Compensation Carrier. | Payer says workers’ compensation pays first; bill the WC carrier, or send the plan the WC denial. | Coordination of benefits | CO-19 guide |
| CO-131 | CARC | CO | Claim specific negotiated discount. | Discount from a single-case agreement, repricer or network deal; check the agreement. | Contractual adjustments | CO-131 guide |
| CO-11 | CARC | CO | The diagnosis is inconsistent with the procedure. | Diagnosis code does not fit the CPT/HCPCS; check pointer, specificity and payer policy. | Coding, modifiers & bundling | CO-11 guide |
| CO-9 | CARC | CO | The diagnosis is inconsistent with the patient’s age. | Diagnosis does not match patient age (pediatric/geriatric ICD edits). | Coding, modifiers & bundling | CO-9 guide |
| CO-10 | CARC | CO | The diagnosis is inconsistent with the patient’s gender. | Diagnosis does not match patient sex (ICD sex edits). | Coding, modifiers & bundling | CO-10 guide |
| CO-5 | CARC | CO | The procedure code/type of bill is inconsistent with the place of service. | Procedure code or bill type does not fit the place of service (POS) reported. | Coding, modifiers & bundling | CO-5 guide |
| CO-6 | CARC | CO | The procedure/revenue code is inconsistent with the patient’s age. | Billed service fails an age edit (procedure or revenue code vs patient age). | Coding, modifiers & bundling | CO-6 guide |
| CO-7 | CARC | CO | The procedure/revenue code is inconsistent with the patient’s gender. | Billed service fails a sex edit (procedure or revenue code vs patient gender). | Coding, modifiers & bundling | CO-7 guide |
| CO-13 | CARC | CO | The date of death precedes the date of service. | Date of death on file is earlier than the service date on the claim. | Eligibility & coverage | CO-13 guide |
| CO-B1 | CARC | CO | Non-covered visits. | Visit treated as non-covered; the remark code gives the reason. | Medical necessity & non-covered | CO-B1 guide |
| CO-B13 | CARC | CO | Previously paid. Payment for this claim/service may have been provided in a previous payment. | Payer says an earlier payment covered this line; find it, compare both lines and confirm you received it. | Duplicates | CO-B13 guide |
| CO-129 | CARC | CO | Prior processing information appears incorrect. | Payer says earlier processing data looks wrong; read the required remark code, then compare your claim with the payer history. | Missing or invalid claim information | CO-129 guide |
| PR-4 | CARC | PR | The procedure code is inconsistent with the modifier used. | Modifier does not fit the procedure code, filed under patient responsibility; ask the payer why. | Coding, modifiers & bundling | PR-4 guide |
| PR-11 | CARC | PR | The diagnosis is inconsistent with the procedure. | Diagnosis does not fit the procedure, filed under patient responsibility; ask the payer why. | Coding, modifiers & bundling | PR-11 guide |
| PR-20 | CARC | PR | This injury/illness is covered by the liability carrier. | Another party’s liability insurer may owe the bill; get carrier and accident details. | Coordination of benefits | PR-20 guide |
| PR-24 | CARC | PR | Charges are covered under a capitation agreement/managed care plan. | Managed care or capitation covers the service; verify the plan, ask what the PR amount is. | Eligibility & coverage | PR-24 guide |
| M5 | RARC | n/a | Monthly rental payments can continue until the earlier of the 15th month from the first rental month, or the month when the equipment is no longer needed. | Equipment rental limit message; count the rental months and check the current cap. | Payment adjustments | M5 guide |
| MA13 | RARC | n/a | Alert: You may be subject to penalties if you bill the patient for amounts not reported with the PR (patient responsibility) group code. | Alert: bill the patient only for amounts under the PR group code. | Contractual & patient responsibility | MA13 guide |
| N3 | RARC | n/a | Missing consent form. | Required consent form not found; for Medicaid sterilization and hysterectomy, attach the complete form. | Missing or invalid information | N3 guide |
| N2 | RARC | n/a | This allowance has been made in accordance with the most appropriate course of treatment provision of the plan. | Allowance set under a plan provision that priced a different treatment; compare billed and paid treatment. | Payment adjustments | N2 guide |
| CARC & RARC guide | Guide | — | How to read group code + CARC + RARC on an 835/ERA. | Explainer for CARCs, RARCs and CO/PR/OA/PI, with links to code pages. | Foundations | CARC & RARC guide |
| OA-18 | CARC | OA | Exact duplicate claim/service (Use only with Group Code OA except where state workers’ compensation regulations requires CO) | Exact duplicate of a claim or service already received. | Duplicates | OA-18 guide |
| CO-29 | CARC | CO | The time limit for filing has expired. | Filed after the timely filing limit. | Timely filing | CO-29 guide |
| CO-45 | CARC | CO / PR | Charge exceeds fee schedule/maximum allowable or contracted/legislated fee arrangement. | Charge is above the allowed or contracted amount (not a true denial). | Contractual & patient responsibility | CO-45 guide |
| PR-1 | CARC | PR | Deductible Amount | Patient’s deductible. | Contractual & patient responsibility | PR-1 guide |
| PR-2 | CARC | PR | Coinsurance Amount | Patient’s coinsurance. | Contractual & patient responsibility | PR-2 guide |
| PR-3 | CARC | PR | Co-payment Amount | Patient’s copay. | Contractual & patient responsibility | PR-3 guide |
| CO-1 | CARC | CO | Deductible Amount | Deductible amount coded as contractual (not the usual PR-1). | Contractual & patient responsibility | CO-1 guide |
| CO-2 | CARC | CO | Coinsurance Amount | Coinsurance amount coded as contractual (not the usual PR-2; not CO-22). | Contractual & patient responsibility | CO-2 guide |
| CO-3 | CARC | CO | Co-payment Amount | Co-payment amount coded as contractual (not the usual PR-3; not CO-307). | Contractual & patient responsibility | CO-3 guide |
| OA-1 | CARC | OA | Deductible Amount | Deductible filed under Other Adjustment: owner not stated, verify before billing the patient. | Contractual & patient responsibility | OA-1 guide |
| OA-2 | CARC | OA | Coinsurance Amount | Coinsurance filed under Other Adjustment: owner not stated, check the math before billing the patient. | Contractual & patient responsibility | OA-2 guide |
| PR-2 | CARC | PR | Coinsurance Amount | Patient coinsurance (dedicated guide; see also PR-1/PR-2/PR-3 overview). | Contractual & patient responsibility | PR-2 dedicated guide |
| CO-B7 | CARC | CO | This provider was not certified/eligible to be paid for this procedure/service on this date of service. | Provider not certified or eligible for this service on this date. | Provider enrollment | CO-B7 guide |
| CO-8 | CARC | CO | The procedure code is inconsistent with the provider type/specialty (taxonomy). | The provider type or taxonomy on the claim can’t bill this code. Check the taxonomy and the payer’s enrollment file. | Provider enrollment | CO-8 guide |
| CO-55 | CARC | CO | Procedure/treatment/drug is deemed experimental/investigational by the payer. | Payer’s medical policy treats the service as experimental. Check the policy and any clinical trial billing. | Medical necessity & non-covered | CO-55 guide |
| CO-107 | CARC | CO | The related or qualifying claim/service was not identified on this claim. | A partner service (such as the base code for an add-on) wasn’t found. Bill them together or link the claims. | Coding, modifiers & bundling | CO-107 guide |
| CO-146 | CARC | CO | Diagnosis was invalid for the date(s) of service reported. | The ICD-10-CM code wasn’t valid on the date of service (often after the October 1 update). Recode and rebill. | Coding, modifiers & bundling | CO-146 guide |
| CO-12 | CARC | CO | The diagnosis is inconsistent with the provider type. | The diagnosis doesn’t fit the provider’s type or specialty. Check the diagnosis pointer, taxonomy and payer file. | Provider enrollment | CO-12 guide |
| CO-14 | CARC | CO | The date of birth follows the date of service. | Birth date on the claim is after the service date, often a newborn or typo error. Correct and resubmit. | Missing / invalid information | CO-14 guide |
| CO-167 | CARC | CO / PR | This (these) diagnosis(es) is (are) not covered. | None of the billed diagnoses are covered for the service (often an LCD or NCD list). Check the policy and the record. | Medical necessity & non-covered | CO-167 guide |
| CO-181 | CARC | CO | Procedure code was invalid on the date of service. | CPT or HCPCS code was deleted or not yet effective on the service date. Recode and send a corrected claim. | Coding, modifiers & bundling | CO-181 guide |
| CO-182 | CARC | CO | Procedure modifier was invalid on the date of service. | A modifier was retired, not yet effective or not accepted by the payer on that date. Fix it and resubmit. | Coding, modifiers & bundling | CO-182 guide |
| CO-226 | CARC | CO | Information requested from the Billing/Rendering Provider was not provided or not provided timely or was insufficient/incomplete. | A payer request for records went unanswered, late or incomplete. Find the request and send what it asked for. | Missing / invalid information | CO-226 guide |
| CO-P1 | CARC | CO | State-mandated Requirement for Property and Casualty, see Claim Payment Remarks Code for specific explanation. | Auto or workers’ comp claim adjusted under a state rule, such as a fee schedule. The remark code names the rule. | Payment adjustments | CO-P1 guide |
| CO-21 | CARC | CO / OA | This injury/illness is the liability of the no-fault carrier. | Health plan says an auto no-fault or PIP carrier should pay first. Bill it, then rebill with its EOB. | Coordination of benefits | CO-21 guide |
| PR-32 | CARC | PR / CO | Our records indicate the patient is not an eligible dependent. | Payer doesn’t list the patient as a dependent on the policy for that date. Check eligibility and the relationship code. | Eligibility & coverage | PR-32 guide |
| PR-33 | CARC | PR / CO | Insured has no dependent coverage. | Subscriber’s plan has no dependent coverage (employee-only or individual). Find the patient’s own coverage. | Eligibility & coverage | PR-33 guide |
| PR-34 | CARC | PR / CO | Insured has no coverage for newborns. | Parent’s plan doesn’t cover the baby yet. Enroll within the special enrollment window and bill the baby separately. | Eligibility & coverage | PR-34 guide |
| PR-35 | CARC | PR / CO | Lifetime benefit maximum has been reached. | Plan says a lifetime cap is used up. Check it’s allowed (not on essential health benefits), then find other coverage. | Frequency / units | PR-35 guide |
| CO-40 | CARC | CO / PR | Charges do not meet qualifications for emergent/urgent care. | Payer says the visit wasn’t emergency or urgent care. Appeal with triage notes showing the presenting symptoms. | Medical necessity & non-covered | CO-40 guide |
| CO-44 | CARC | CO | Prompt-pay discount. | Contract discount for fast payment. Check the clause, payment date and math; dispute if wrong. | Payment adjustments | CO-44 guide |
| CO-51 | CARC | CO / PR | These are non-covered services because this is a pre-existing condition. | Pre-existing condition exclusion. Check the plan type first; most ACA plans can’t apply it. | Medical necessity & non-covered | CO-51 guide |
| CO-18 | CARC | CO / OA | Exact duplicate claim/service (Use only with Group Code OA except where state workers’ compensation regulations requires CO) | Duplicate claim under the CO group. Expected mainly in some workers’ comp states; match the original and correct it, don’t resend. | Duplicates | CO-18 guide |
| PR-3 | CARC | PR / CO | Co-payment Amount | The patient’s fixed copay. Post it, match front-desk collections, and never bill QMB patients for it. | Contractual & patient responsibility | PR-3 guide |
| CO-15 | CARC | CO | The authorization number is missing, invalid, or does not apply to the billed services or provider. | Retired code (stopped 05/01/2018) for an authorization mismatch. Match the auth to the provider, code and dates, then correct. | Authorization | CO-15 guide |
| N29 | RARC | n/a | Missing documentation/orders/notes/summary/report/chart. | Retired remark (stopped 03/01/2016) asking for records. Find out which record the payer needs and send it. | Missing or invalid information | N29 guide |
| CO-53 | CARC | CO / PR | Services by an immediate relative or a member of the same household are not covered. | A relative or household member gave the care. Check who rendered it and the relationship; appeal only if the payer got the facts wrong. | Medical necessity & non-covered | CO-53 guide |
| CO-54 | CARC | CO | Multiple physicians/assistants are not covered in this case. | Assistant, co-surgeon or team surgeon not covered for this code. Check the MPFS indicators and modifiers 80, 82 and AS. | Coding, modifiers & bundling | CO-54 guide |
| CO-56 | CARC | CO / PR | Procedure/treatment has not been deemed ‘proven to be effective’ by the payer. | Payer’s medical policy treats the service as unproven. Match the policy criteria or appeal with guidelines and studies. | Medical necessity & non-covered | CO-56 guide |
| CO-58 | CARC | CO | Treatment was deemed by the payer to have been rendered in an inappropriate or invalid place of service. | Wrong or non-covered place of service. Match the POS to where care happened, then send a corrected claim. | Coding, modifiers & bundling | CO-58 guide |
| CO-61 | CARC | CO / PR | Adjusted for failure to obtain second surgical opinion | Plan required a second surgical opinion before elective surgery. Send the opinion or show the case was exempt. | Authorization | CO-61 guide |
| PR-66 | CARC | PR | Blood Deductible. | Patient’s blood deductible (Medicare: first 3 units a year). Check donor-replaced units and value codes 38 and 39. | Contractual & patient responsibility | PR-66 guide |
| CO-69 | CARC | CO | Day outlier amount. | Day outlier adjustment on a long DRG stay. Check the contract threshold, day rate and covered days. | Payment adjustments | CO-69 guide |
| CO-74 | CARC | CO | Indirect Medical Education Adjustment. | IME part of a teaching hospital payment added or carved out. For MA stays, file the IME-only claim (condition codes 04 and 69). | Payment adjustments | CO-74 guide |
| CO-75 | CARC | CO | Direct Medical Education Adjustment. | Direct GME adjustment. Medicare pays DGME mostly on the cost report; check the contract carve-out. | Payment adjustments | CO-75 guide |
| CO-76 | CARC | CO | Disproportionate Share Adjustment. | DSH part of a hospital payment added or carved out. Check the contract and keep MA shadow claims flowing. | Payment adjustments | CO-76 guide |
| CO-78 | CARC | CO | Non-Covered days/Room charge adjustment. | Some inpatient days or the room rate were not covered. Audit the day count, level of care and room type, then rebill. | Payment adjustments | CO-78 guide |
| PR-85 | CARC | PR | Patient Interest Adjustment (Use Only Group code PR) | Interest the patient owes, not payer late-payment interest. Confirm who owes it and post to the right account. | Payment adjustments | PR-85 guide |
| CO-89 | CARC | CO | Professional fees removed from charges. | Doctor fees (rev codes 096X-098X) were taken off a facility claim. Bill them on an 837P unless the CAH optional method applies. | Payment adjustments | CO-89 guide |
| CO-90 | CARC | CO | Ingredient cost adjustment. | Drug price cut to the payer benchmark (MAC, NADAC, ASP). Check NDC and units first, then appeal with the invoice. | Payment adjustments | CO-90 guide |
| CO-91 | CARC | CO | Dispensing fee adjustment. | The fee for filling a drug was cut. Check the fee code (G0333, Q0513, Q0514), fees per period and refill timing. | Payment adjustments | CO-91 guide |
| OA-94 | CARC | OA | Processed in Excess of charges. | The payer paid more than you billed. Post the negative adjustment, and review charges set below fee schedules. | Payment adjustments | OA-94 guide |
| CO-95 | CARC | CO, PR, OA | Plan procedures not followed. | A plan step such as a referral or notification was missed. Find the rule from the RARC, prove it was followed or fix the record. | Authorization | CO-95 guide |
| OA-100 | CARC | OA, PR, CO | Payment made to patient/insured/responsible party. | The payer paid the patient, not you. Post it as paid to patient and bill the patient with the EOB; don’t write it off. | Payment adjustments | OA-100 guide |
| OA-101 | CARC | OA | Predetermination: anticipated payment upon completion of services or claim adjudication. | An estimate of benefits, not a payment or an approval. Check prior authorization separately and bill a normal claim after care. | Authorization | OA-101 guide |
| PR-102 | CARC | PR, CO, OA | Major Medical Adjustment. | The plan’s major medical layer paid, often with its own deductible or coinsurance. Post the PR amount to the patient and explain it. | Contractual & patient responsibility | PR-102 guide |
| CO-103 | CARC | CO | Provider promotional discount (e.g., Senior citizen discount). | The payer cut payment to match a discount you gave. Correct billing-system errors; review real promos with compliance. | Payment adjustments | CO-103 guide |
| CO-104 | CARC | CO | Managed care withholding. | The plan held back part of the payment under your contract. Track it separately, dispute withholds on exempt services, match the settlement. | Payment adjustments | CO-104 guide |
| CO-105 | CARC | CO, OA | Tax withholding. | Tax was taken from the payment, usually IRS backup withholding after a name/TIN mismatch. Send a corrected W-9 and log the amounts. | Payment adjustments | CO-105 guide |
| CO-108 | CARC | CO | Rent/purchase guidelines were not met. | DME rent or purchase rules broken, often a capped rental past its months. Check the month count, modifiers and any break in need. | Medical necessity & non-covered | CO-108 guide |
| CO-110 | CARC | CO | Billing date predates service date. | The claim went out before its own service dates, often an auto-filled end date. Bill after the service ends with real dates. | Coding, modifiers & bundling | CO-110 guide |
| CO-111 | CARC | CO | Not covered unless the provider accepts assignment. | The service needs assignment and the claim said no. Check Box 27 and Box 13, fix the default and send a corrected claim. | Contractual & patient responsibility | CO-111 guide |
| CO-112 | CARC | CO | Service not furnished directly to the patient and/or not documented. | The records didn’t prove the service, or the patient wasn’t served directly. Appeal with the full signed record when it exists. | Medical necessity & non-covered | CO-112 guide |
| CO-114 | CARC | CO | Procedure/product not approved by the Food and Drug Administration. | The payer thinks the drug or device lacks FDA approval. Check status, add a missing IDE number or NDC, or appeal with proof. | Medical necessity & non-covered | CO-114 guide |
| CO-115 | CARC | CO | Procedure postponed, canceled, or delayed. | The billed procedure didn’t happen as reported. Rebill stopped cases with 73/74 or 52/53 and a Z53 code; void canceled ones. | Coding, modifiers & bundling | CO-115 guide |
| CO-116 | CARC | CO | The advance indemnification notice signed by the patient did not comply with requirements. | The ABN failed Medicare rules, so the patient isn’t liable. Appeal with a valid signed ABN, or refund and write off. | Medical necessity & non-covered | CO-116 guide |
| CO-117 | CARC | CO | Transportation is only covered to the closest facility that can provide the necessary care. | Ambulance paid only to the nearest facility that could treat the patient. Appeal with run report proof when a nearer one couldn’t. | Medical necessity & non-covered | CO-117 guide |
| CO-118 | CARC | CO | ESRD network support adjustment. | Medicare’s 50-cent per-treatment dialysis cut that funds ESRD networks. Post as contractual; it shouldn’t appear on AKI claims. | Payment adjustments | CO-118 guide |
| CO-122 | CARC | CO | Psychiatric reduction. | A cut on mental health services. Medicare’s limit reached 100% in 2014; if a plan still cuts, ask for the contract term and dispute. | Payment adjustments | CO-122 guide |
| CO-128 | CARC | CO | Newborn’s services are covered in the mother’s Allowance. | The payer says the baby’s care was paid in the mother’s delivery payment. Write off routine nursery if bundled; appeal special care with records. | Coding, modifiers & bundling | CO-128 guide |
| CO-130 | CARC | CO | Claim submission fee. | The payer deducted a fee for handling the claim. Find the contract term; dispute fees on electronic claims or with no supporting term. | Payment adjustments | CO-130 guide |
| CO-132 | CARC | CO | Prearranged demonstration project adjustment. | Payment changed under a demonstration or pilot program. Confirm the program, the patient’s enrollment and the model’s payment terms. | Payment adjustments | CO-132 guide |
| CO-140 | CARC | CO, PR | Patient/Insured health identification number and name do not match. | The member ID was found but the name doesn’t fit it. Copy the name and ID exactly from eligibility and send a corrected claim. | Eligibility | CO-140 guide |
| CO-134 | CARC | CO | Technical fees removed from charges. | The payer paid only the professional part. Check the setting and equipment owner, then rebill with modifier 26 or appeal with proof. | Payment adjustments | CO-134 guide |
| OA-133 | CARC | OA | The disposition of this service line is pending further review. (Use only with Group Code OA). | A line is on hold, not denied. Post it as pended, answer records requests and watch for the reversal and final result. | Claim status | OA-133 guide |
| CO-135 | CARC | CO | Interim bills cannot be processed. | The payer won’t take an interim facility bill. Check the type of bill frequency digit and send one claim after discharge if required. | Claim data | CO-135 guide |
| OA-136 | CARC | OA | Failure to follow prior payer’s coverage rules. (Use only with Group Code OA) | The secondary won’t pay because a primary plan rule was missed. Fix or appeal the primary claim, then rebill the secondary. | Coordination of benefits | OA-136 guide |
| CO-139 | CARC | CO | Contracted funding agreement – Subscriber is employed by the provider of services. Use only with Group Code CO. | The subscriber works for the provider, so a funding agreement applies. Confirm employment, bill only the PR share and post the rest internally. | Payment adjustments | CO-139 guide |
| PR-142 | CARC | PR | Monthly Medicaid patient liability amount. | Medicaid cut its payment by the resident’s monthly liability. Match it to the state notice and bill it to the resident or representative. | Patient responsibility | PR-142 guide |
| CO-144 | CARC | CO | Incentive adjustment, e.g. preferred product/service. | An incentive changed the payment, often extra money such as a positive MIPS adjustment. Read the sign and post it to its own code. | Payment adjustments | CO-144 guide |
| CO-143 | CARC | CO | Portion of payment deferred. | Part of the payment is held for later, often a contract withhold. Post it to a tracking account and match it to the settlement. | Payment adjustments | CO-143 guide |
| CO-147 | CARC | CO | Provider contracted/negotiated rate expired or not on file. | The payer has no active rate for you on file. Find the contract, rate or location gap, fix the load and ask for batch reprocessing. | Contractual & patient responsibility | CO-147 guide |
| CO-148 | CARC | CO | Information from another provider was not provided or was insufficient/incomplete. | The payer needs records from another provider, such as the ordering doctor. Get exactly what’s missing and send a reconsideration. | Missing / invalid information | CO-148 guide |
| PR-149 | CARC | PR | Lifetime benefit maximum has been reached for this service/benefit category. | The patient used up a lifetime limit for this benefit. Confirm the cap is allowed and counted right, then appeal or bill the patient. | Contractual & patient responsibility | PR-149 guide |
| CO-150 | CARC | CO | Payer deems the information submitted does not support this level of service. | The payer says the records don’t support the level billed, often an E/M visit. Score the note and appeal only what it proves. | Coding, modifiers & bundling | CO-150 guide |
| CO-152 | CARC | CO | Payer deems the information submitted does not support this length of service. | The payer says the time or days billed aren’t supported. Match the documented time to the code, then correct or appeal. | Frequency / units | CO-152 guide |
| CO-153 | CARC | CO | Payer deems the information submitted does not support this dosage. | The payer says the drug dose billed isn’t supported, often a unit math error. Convert the dose to HCPCS units and correct or appeal. | Frequency / units | CO-153 guide |
| CO-154 | CARC | CO | Payer deems the information submitted does not support this day’s supply. | The day’s supply doesn’t match the quantity and directions. Recalculate, apply package and plan limits, and rebill. | Frequency / units | CO-154 guide |
| CO-155 | CARC | CO | Patient refused the service/procedure. | The payer believes the patient declined the service billed. Remove it and refund if it wasn’t done, or appeal with the note if it was. | Medical necessity & non-covered | CO-155 guide |
| PR-157 | CARC | PR | Service/procedure was provided as a result of an act of war. | The plan says the care came from an act of war. Remove a war cause code that doesn’t fit, or look to VA or TRICARE. | Medical necessity & non-covered | PR-157 guide |
| PR-158 | CARC | PR | Service/procedure was provided outside of the United States. | The payer thinks care happened outside the US. Appeal if it was in a state or territory; otherwise check travel benefits. | Medical necessity & non-covered | PR-158 guide |
| PR-160 | CARC | PR | Injury/illness was the result of an activity that is a benefit exclusion. | The plan excludes the activity that caused the injury. Appeal if a medical condition or domestic violence caused it. | Medical necessity & non-covered | PR-160 guide |
| PR-106 | CARC | PR, OA | Patient payment option/election not in effect. | The patient’s chosen plan option wasn’t active on the date of service. Check the member ID suffix and option, then correct the claim or bill the patient. | Eligibility | PR-106 guide |
| OA-121 | CARC | OA, CO | Indemnification adjustment – compensation for outstanding member responsibility. | The payer adjusted for the member’s unpaid share, often adding to your payment. Check the contract and stop patient billing for any covered amount. | Payment adjustments | OA-121 guide |
| CO-137 | CARC | CO, OA | Regulatory Surcharges, Assessments, Allowances or Health Related Taxes. | A surcharge, assessment or health tax set by law changed the payment. Check the program rate, post it on its own code and don’t bill the patient. | Payment adjustments | CO-137 guide |
| CO-159 | CARC | CO | Service/procedure was provided as a result of terrorism. | The plan excluded care caused by terrorism. Confirm the cause codes, then bill workers’ compensation or the program that covers the event. | Coverage | CO-159 guide |
| CO-161 | CARC | CO | Provider performance bonus | The payer added a performance bonus, usually as a negative adjustment that raises payment. Post it to an incentive code and don’t refund it. | Payment adjustments | CO-161 guide |
| CO-163 | CARC | CO | Attachment/other documentation referenced on the claim was not received. | The payer never matched the attachment your claim referenced. Check the PWK control number, resend with a matching cover sheet or correct the claim. | Documentation | CO-163 guide |
| CO-164 | CARC | CO | Attachment/other documentation referenced on the claim was not received in a timely fashion. | The records arrived after the payer’s attachment window. Appeal with proof of a timely send, or send a new claim with the records the same day. | Documentation | CO-164 guide |
| CO-166 | CARC | CO | These services were submitted after this payers responsibility for processing claims under this plan ended. | The payer no longer processes claims for that plan. Find the successor payer for the date of service and send it a new claim. | Eligibility | CO-166 guide |
| CO-169 | CARC | CO, PR | Alternate benefit has been provided. | The plan paid the benefit for a cheaper alternative service. Your contract decides who owes the difference; appeal if the alternate wasn’t adequate. | Coverage | CO-169 guide |
| CO-170 | CARC | CO | Payment is denied when performed/billed by this type of provider. | The payer won’t pay the service for this provider type. Read the policy, check the rendering provider, and correct only when the rules and record allow it. | Provider | CO-170 guide |
| CO-171 | CARC | CO | Payment is denied when performed/billed by this type of provider in this type of facility. | The payer won’t pay this provider type in this setting. Check the place of service first; correct it, or bill the facility if it owes you. | Provider | CO-171 guide |
| CO-172 | CARC | CO | Payment is adjusted when performed/billed by a provider of this specialty. | The payer changed the rate because of the specialty on file. Compare the payer file, NPPES and the claim, then fix enrollment and rebill with taxonomy. | Provider | CO-172 guide |
| CO-173 | CARC | CO | Service/equipment was not prescribed by a physician. | The claim doesn’t show a physician or accepted prescriber. Check who signed the order, fix Box 17 and 17b, or get a valid order. | Documentation | CO-173 guide |
| CO-174 | CARC | CO | Service was not prescribed prior to delivery. | The claim shows delivery before the order date. Line up the dates; correct Box 24A if wrong, or check the plan’s verbal order rules. | Documentation | CO-174 guide |
| CO-175 | CARC | CO | Prescription is incomplete. | The order is missing a required element such as quantity or frequency. Get a signed addendum, match the claim units to it and resubmit. | Documentation | CO-175 guide |
| CO-176 | CARC | CO | Prescription is not current. | The order had expired on the date of service. Check for a renewal signed in time, report it on a corrected claim, and track order end dates. | Documentation | CO-176 guide |
| PR-177 | CARC | PR | Patient has not met the required eligibility requirements. | The patient failed a plan eligibility rule such as age or relationship. Check for other coverage and bill that plan before billing the patient. | Eligibility | PR-177 guide |
| PR-178 | CARC | PR | Patient has not met the required spend down requirements. | Medicaid won’t pay until the patient’s spend-down is met. Help report bills, recheck eligibility and ask for reprocessing; bill only the spend-down share. | Eligibility | PR-178 guide |
| PR-179 | CARC | PR | Patient has not met the required waiting requirements. | The patient was still in a waiting period. Look for coverage that bridged the gap, such as COBRA, and bill that plan before billing the patient. | Eligibility | PR-179 guide |
| PR-180 | CARC | PR | Patient has not met the required residency requirements. | The patient didn’t meet residency rules, usually after a move. Find the state program or plan that covered the date and bill it. | Eligibility | PR-180 guide |
| CO-183 | CARC | CO | The referring provider is not eligible to refer the service billed. | The payer won’t accept the referrer on the claim. Put the provider who signed the referral or order in Box 17 / FL 78 and send a corrected claim. | Provider | CO-183 guide |
| CO-184 | CARC | CO | The prescribing/ordering provider is not eligible to prescribe/order the service billed. | The payer won’t accept the ordering provider on the claim. Bill the provider who signed the order (Box 17 DK) or get a new order from an eligible provider. | Provider | CO-184 guide |
| CO-185 | CARC | CO | The rendering provider is not eligible to perform the service billed. | The payer won’t accept the rendering provider for this service. Check who performed it, correct Box 24J / FL 77, or fix enrollment and scope issues. | Provider | CO-185 guide |
| CO-186 | CARC | CO | Level of care change adjustment. | The payer paid at a different level of care, often observation instead of inpatient. Match the claim to the order and authorization, or appeal with the record. | Coverage | CO-186 guide |
| PR-187 | CARC | PR | Consumer Spending Account payments (includes but is not limited to Flexible Spending Account, Health Savings Account, Health Reimbursement Account, etc.) | Part of the patient’s share was paid from an HSA, FSA or HRA. Post it as a payment and bill the patient only for what is left. | Patient responsibility | PR-187 guide |
| CO-188 | CARC | CO | This product/procedure is only covered when used according to FDA recommendations. | The payer covers the product only for its FDA-labeled use. Code the documented labeled indication and rebill, or appeal off-label use with compendia support. | Coverage | CO-188 guide |
| CO-189 | CARC | CO | ‘Not otherwise classified’ or ‘unlisted’ procedure code (CPT/HCPCS) was billed when there is a specific procedure code for this procedure/service | An unlisted or NOC code was billed when a specific code exists. Bill the specific CPT/HCPCS code with the right units on a corrected claim. | Coding | CO-189 guide |
| CO-190 | CARC | CO | Payment is included in the allowance for a Skilled Nursing Facility (SNF) qualified stay. | The service is paid through the SNF’s stay. Bill excluded parts (such as the -26 reading) yourself and invoice the SNF for the rest. | Bundling | CO-190 guide |
| CO-193 | CARC | CO | Original payment decision is being maintained. Upon review, it was determined that this claim was processed properly. | The payer reviewed the claim again and kept its decision. Answer the reviewer’s rationale in a next-level appeal, or send a corrected claim for real data errors. | Appeals | CO-193 guide |
| CO-194 | CARC | CO | Anesthesia performed by the operating physician, the assistant surgeon or the attending physician. | The claim shows the surgeon gave anesthesia. If a CRNA or anesthesiologist did, rebill under that NPI with the anesthesia modifier; if not, it isn’t separately payable. | Anesthesia | CO-194 guide |
| OA-195 | CARC | OA | Refund issued to an erroneous priority payer for this claim/service. | This payer refunded another payer that paid as primary by mistake. Post it as a refund made for you and match it to the other payer’s overpayment request. | Coordination of benefits | OA-195 guide |
| CO-198 | CARC | CO | Precertification/notification/authorization/pre-treatment exceeded. | The services billed went past the approved visits, units or dates. Get an extension or retro approval and rebill with the new number in Box 23 / FL 63. | Authorization | CO-198 guide |
| CO-199 | CARC | CO | Revenue code and Procedure code do not match. | The UB-04 revenue code (FL 42) doesn’t fit the CPT/HCPCS code (FL 44). Fix the charge master entry and send a replacement claim. | Coding | CO-199 guide |
| PR-201 | CARC | PR | Patient is responsible for amount of this claim/service through ‘set aside arrangement’ or other agreement. (Use only with Group Code PR) At least one Remark Code must be provided (may be comprised of either the NCPDP Reject Reason Code, or Remittance Advice Remark Code that is not an ALERT.) | A settlement set-aside must pay for care for the injury. Bill the set-aside administrator and keep the denial for when the funds run out. | Patient responsibility | PR-201 guide |
| PR-202 | CARC | PR | Non-covered personal comfort or convenience services. | The plan treated the charge as a comfort item (TV, phone, guest tray, kit). Bill the patient only for true comfort items; fix supplies mapped to 099X codes. | Coverage | PR-202 guide |
| CO-203 | CARC | CO | Discontinued or reduced service. | The service was stopped early or reduced, and the claim didn’t show it. Add modifier 52/53 (professional) or 73/74 (facility) and rebill. | Modifiers | CO-203 guide |
| CO-205 | CARC | CO | Pharmacy discount card processing fee | A discount card program’s processing fee on a pharmacy claim. Post it as a contractual fee and dispute it if it doesn’t match the agreement. | Pharmacy | CO-205 guide |
| CO-206 | CARC | CO | National Provider Identifier – missing. | A required NPI field was blank (billing, rendering or referring). Use the remark to find the box, fill it from NPPES and resubmit. | Provider | CO-206 guide |
| CO-207 | CARC | CO | National Provider identifier – Invalid format | An NPI failed the format check (wrong length or check digit). Copy the right 10-digit NPI from NPPES, fix the profile and resubmit. | Provider | CO-207 guide |
| CO-208 | CARC | CO | National Provider Identifier – Not matched. | The NPI is valid but doesn’t match the payer’s file (tax ID, address or enrollment). Fix the claim setup or the enrollment, then resubmit. | Provider | CO-208 guide |
| CO-210 | CARC | CO | Payment adjusted because pre-certification/authorization not received in a timely fashion | The payer says the authorization or admission notice arrived after its deadline. Prove timely notice or fix the auth number on the claim. | Authorization | CO-210 guide |
| OA-209 | CARC | OA | Per regulatory or other agreement. The provider cannot collect this amount from the patient. However, this amount may be billed to subsequent payer. Refund to patient if collected. (Use only with Group code OA) | A law or agreement (often QMB rules) bars billing the patient. Refund any amount collected and bill Medicaid or the next payer. | Patient responsibility | OA-209 guide |
| CO-211 | CARC | CO | National Drug Codes (NDC) not eligible for rebate, are not covered. | Medicaid won’t pay because the NDC billed is not in the drug rebate program. Bill the NDC of the vial used, or write off and change suppliers. | Drugs / NDC | CO-211 guide |
| CO-212 | CARC | CO | Administrative surcharges are not covered | The payer won’t pay office fees such as record copying (S9981) or form charges. Remove or write off the line; don’t bill the patient. | Non-covered | CO-212 guide |
| CO-213 | CARC | CO | Non-compliance with the physician self referral prohibition legislation or payer policy. | The payer says the referral broke Stark or its self-referral policy. Don’t rebill; check the financial tie and exception with compliance. | Compliance | CO-213 guide |
| CO-215 | CARC | CO | Based on subrogation of a third party settlement | The plan recovered or reversed payment because a third-party injury settlement should cover the care. Bill the settlement, carrier or lien. | COB / liability | CO-215 guide |
| CO-216 | CARC | CO | Based on the findings of a review organization or the payer’s findings. | A review organization (such as a QIO) or the payer’s reviewer denied or reduced the claim. Get the findings and appeal with full records. | Medical review | CO-216 guide |
| CO-219 | CARC | CO | Based on extent of injury. | Workers’ comp or a liability payer denied care outside the accepted injury. Split the claim and bill unaccepted care to the right plan. | Workers’ comp / liability | CO-219 guide |
| CO-222 | CARC | CO | Exceeds the contracted maximum number of hours/days/units by this provider for this period. This is not patient specific. | The provider used up its contract cap on hours, days or units for the period. Audit the count and ask for a cap change. | Contract limits | CO-222 guide |
| CO-223 | CARC | CO | Adjustment code for mandated federal, state or local law/regulation that is not already covered by another code and is mandated before a new code can be created. | The payer adjusted the claim under a law with no code of its own, such as a surprise billing law. Find the law and check the math. | Regulatory | CO-223 guide |
| CO-224 | CARC | CO | Patient identification compromised by identity theft. Identity verification required for processing this and future claims. | The payer suspects identity theft and needs proof of identity before paying this or future claims. Verify with the payer’s SIU. | Eligibility / fraud | CO-224 guide |
| CO-228 | CARC | CO | Denied for failure of this provider, another provider or the subscriber to supply requested information to a previous payer for their adjudication | The secondary denied because the primary never got information it asked for. Answer the primary, then rebill secondary. | COB | CO-228 guide |
| CO-231 | CARC | CO | Mutually exclusive procedures cannot be done in the same day/setting. | Two billed procedures can’t both be done in one session, such as complete and limited exams. Bill the one the report supports. | Coding / NCCI | CO-231 guide |
| CO-232 | CARC | CO | Institutional Transfer Amount. | A DRG payment was cut because the claim shows care crossing hospitals. Check the FL 17 discharge status; fix it if the patient went home. | Inpatient / DRG | CO-232 guide |
| CO-233 | CARC | CO | Services/charges related to the treatment of a hospital-acquired condition or preventable medical error. | Charges tied to a hospital-acquired condition were removed. Check each POA indicator; fix N to Y only if admission notes support it. | Inpatient / quality | CO-233 guide |
| CO-235 | CARC | CO | Sales Tax | The payer cut the sales tax part of the charge because the item is exempt (N659) or tax is in the rate (N660). Post it as a write-off. | Pricing / posting | CO-235 guide |
| CO-237 | CARC | CO | Legislated/Regulatory Penalty | A penalty applied by law, regulation or plan rule, such as a MIPS cut (N807). Check it and post it; rebilling will not remove it. | Payment adjustment | CO-237 guide |
| PR-238 | CARC | PR | Claim spans eligible and ineligible periods of coverage, this is the reduction for the ineligible period. (Use only with Group Code PR) | The claim crossed a coverage change, so the payer cut the uncovered days to patient responsibility. Check for other coverage first. | Eligibility | PR-238 guide |
| CO-239 | CARC | CO | Claim spans eligible and ineligible periods of coverage. Rebill separate claims. | The claim mixed covered and uncovered dates. Split it at the coverage change and rebill each part to the right payer. | Eligibility | CO-239 guide |
| CO-240 | CARC | CO | The diagnosis is inconsistent with the patient’s birth weight. | The newborn’s weight-based P07 code does not match the birth weight (value code 54). Fix the wrong one and send a replacement claim. | Coding | CO-240 guide |
| PR-241 | CARC | PR | Low Income Subsidy (LIS) Co-payment Amount | The member’s reduced Part D copay under Extra Help. Collect only this amount and refund any overcharge. | Patient responsibility | PR-241 guide |
| CO-243 | CARC | CO | Services not authorized by network/primary care providers. | The plan found no PCP or network referral. Report the referring PCP and referral number and send a corrected claim. | Authorization | CO-243 guide |
| CO-245 | CARC | CO | Provider performance program withhold. | Part of the payment is held under a performance program in your contract. Track it as a receivable, not a write-off. | Payment adjustment | CO-245 guide |
| CO-246 | CARC | CO | This non-payable code is for required reporting only. | The line is a reporting code, such as a CPT II quality code, and never pays. Bill it at $0.00 and post it at zero. | Coding | CO-246 guide |
| CO-249 | CARC | CO | This claim has been identified as a readmission. (Use only with Group Code CO) | The payer linked this stay to an earlier one. Combine related same-day stays, add condition code B4 if unrelated, or appeal. | Facility | CO-249 guide |
| CO-250 | CARC | CO | The attachment/other documentation that was received was the incorrect attachment/document. The expected attachment/document is still missing. | The payer got the wrong document. Send the exact record it asked for, linked to the claim. | Documentation | CO-250 guide |
| CO-251 | CARC | CO | The attachment/other documentation that was received was incomplete or deficient. The necessary information is still needed to process the claim. | The records sent were incomplete or unsigned. Send the full signed packet before the deadline. | Documentation | CO-251 guide |
| CO-254 | CARC | CO | Claim received by the dental plan, but benefits not available under this plan. Submit these services to the patient’s medical plan for further consideration. | Not a dental benefit and not forwarded. Rebuild the claim with medical codes and bill the medical plan. | Coordination | CO-254 guide |
| CO-258 | CARC | CO | Claim/service not covered when patient is in custody/incarcerated. Applicable federal, state or local authority may cover the claim/service. | The payer thinks the patient was in custody. Bill the responsible authority, or send proof of release. | Eligibility | CO-258 guide |
| CO-268 | CARC | CO | The Claim spans two calendar years. Please resubmit one claim per calendar year. | The claim crosses 31 December. Split it and send one claim for each calendar year. | Billing format | CO-268 guide |
| CO-270 | CARC | CO | Claim received by the medical plan, but benefits not available under this plan. Submit these services to the patient’s dental plan for further consideration. | The medical plan treats this as dental care. Send a claim to the patient’s dental plan. | Coordination of benefits | CO-270 guide |
| CO-273 | CARC | CO | Coverage/program guidelines were exceeded. | The service passed a plan or program limit. Check whether an exception applies. | Coverage | CO-273 guide |
| CO-274 | CARC | CO | Fee/Service not payable per patient Care Coordination arrangement. | Another provider or program is already paid to coordinate this patient’s care. | Contract | CO-274 guide |
| OA-257 | CARC | OA | The disposition of the claim/service is undetermined during the premium payment grace period, per Health Insurance Exchange requirements. | A Marketplace plan is holding the claim during a premium grace period. Track the end date; it will be reprocessed. | Eligibility | OA-257 guide |
| CO-261 | CARC | CO | The procedure or service is inconsistent with the patient’s history. | The service conflicts with past claims, often a wrong RT/LT. Fix the side or code, or appeal a real repeat. | Coding | CO-261 guide |
| CO-267 | CARC | CO | Claim/service spans multiple months. | The claim crosses months. Split it into monthly claims with interim bill types and matching dates. | Billing format | CO-267 guide |
| CO-269 | CARC | CO | Anesthesia not covered for this service/procedure. | The plan won’t pay for anesthesia with this procedure. Check the policy’s exceptions. | Coverage | CO-269 guide |
| CO-272 | CARC | CO | Coverage/program guidelines were not met. | A program rule tied to the service wasn’t met. Find the rule and send proof. | Coverage | CO-272 guide |
| PR-275 | CARC | PR | Prior payer’s (or payers’) patient responsibility (deductible, coinsurance, co-payment) not covered. (Use only with Group Code PR) | The secondary plan won’t pay the primary plan’s deductible, coinsurance or copay. | Coordination of benefits | PR-275 guide |
| CO-20 | CARC | CO | This injury/illness is covered by the liability carrier. | The payer thinks another party’s liability insurer should pay for this injury. | Coordination of benefits | CO-20 guide |
| CO-276 | CARC | CO | Services denied by the prior payer(s) are not covered by this payer. | The primary plan denied the service, so the secondary won’t pay. Fix the primary denial first. | Coordination of benefits | CO-276 guide |
| PR-247 | CARC | PR | Deductible for Professional service rendered in an Institutional setting and billed on an Institutional claim. | The Part B deductible for doctor services paid inside a Medicare bundled hospital claim. The patient or a secondary plan owes it. | Patient responsibility | PR-247 guide |
| PR-248 | CARC | PR | Coinsurance for Professional service rendered in an Institutional setting and billed on an Institutional claim. | The Part B coinsurance for doctor services paid inside a Medicare bundled hospital claim. The secondary plan or the patient owes it, never a QMB patient. | Patient responsibility | PR-248 guide |
| CO-260 | CARC | CO | Processed under Medicaid ACA Enhanced Fee Schedule | Medicaid priced the service on the ACA enhanced primary care fee schedule. A contractual write-off; check the allowed amount against the enhanced rate. | Payment adjustment | CO-260 guide |
| CO-259 | CARC | CO | Additional payment for Dental/Vision service utilization. | The payer added money to a dental or vision line. The CAS amount is usually negative; post it as an added payment, not a write-off. | Payment adjustment | CO-259 guide |
| CO-262 | CARC | CO | Adjustment for delivery cost. Usage: To be used for pharmaceuticals only. | The plan reduced or refused the delivery cost a pharmacy claimed (NCPDP 479-H8 qualifier 01). Write off or correct per the payer sheet. | Drugs / NDC | CO-262 guide |
| CO-263 | CARC | CO | Adjustment for shipping cost. Usage: To be used for pharmaceuticals only. | The plan reduced or refused the shipping cost on a pharmacy claim (NCPDP qualifier 02). Part D counts delivery in the dispensing fee. | Drugs / NDC | CO-263 guide |
| PR-6 | CARC | PR | The procedure/revenue code is inconsistent with the patient’s age. | The code doesn’t fit the patient’s age and the plan put the balance on the patient. Check the birth date and age band first. | Patient responsibility | PR-6 guide |
| PR-8 | CARC | PR | The procedure code is inconsistent with the provider type/specialty (taxonomy). | The plan says the service doesn’t fit the provider type or taxonomy and put the balance on the patient. Check the rendering provider and taxonomy first. | Patient responsibility | PR-8 guide |
| PR-10 | CARC | PR | The diagnosis is inconsistent with the patient’s gender. | The diagnosis conflicts with the sex on the claim and the plan billed the patient. Usually a registration error; check before sending a statement. | Patient responsibility | PR-10 guide |
| PR-14 | CARC | PR | The date of birth follows the date of service. | The claim shows a birth date later than the service date. Almost always a typo; correct the date and resend instead of billing the patient. | Patient responsibility | PR-14 guide |
| PR-16 | CARC | PR | Claim/service lacks information or has submission/billing error(s). | The claim is missing or has invalid data, often the member ID or information the member must supply. Read the remark code, fix it and resubmit before billing the patient. | Patient responsibility | PR-16 guide |
| PR-18 | CARC | PR | Exact duplicate claim/service (Use only with Group Code OA except where state workers’ compensation regulations requires CO) | The payer matched the line to one already received but labeled it patient share. X12 limits code 18 to OA, so hold the bill and check the original claim. | Patient responsibility | PR-18 guide |
| PR-23 | CARC | PR | The impact of prior payer(s) adjudication including payments and/or adjustments. (Use only with Group Code OA) | A secondary payer reported what the primary paid or wrote off as patient share. X12 allows only OA, so bill the patient only the primary’s real cost share. | Patient responsibility | PR-23 guide |
| CO-264 | CARC | CO | Adjustment for postage cost. Usage: To be used for pharmaceuticals only. | The plan reduced or refused the postage on a mailed pharmacy claim (NCPDP qualifier 03). Part D counts delivery in the dispensing fee. | Drugs / NDC | CO-264 guide |
| CO-265 | CARC | CO | Adjustment for administrative cost. Usage: To be used for pharmaceuticals only. | The plan reduced or refused an administrative cost on a pharmacy claim (NCPDP qualifier 04). Overhead is usually paid in the dispensing fee. | Drugs / NDC | CO-265 guide |
| CO-266 | CARC | CO | Adjustment for compound preparation cost. Usage: To be used for pharmaceuticals only. | The plan reduced or refused the compound preparation cost on a pharmacy claim (NCPDP qualifier 09). Part D counts mixing in the dispensing fee. | Drugs / NDC | CO-266 guide |
Denial codes by category
Missing or invalid claim information
The claim reached the payer but couldn’t be adjudicated as sent. Start with CO-16, then check the remark code: N290 (rendering NPI), M51 (procedure code), MA130 (unprocessable, no appeal rights). CO-252 is the code payers use when an attachment is missing. PR-227 / CO-227 means information requested from the patient/insured was missing or incomplete (not the same as provider-side CO-226). CO-A1 is the catch-all denial that requires a remark when no more specific CARC fits. N3 means a required consent form was not found (often a Medicaid sterilization or hysterectomy form).
Eligibility and coverage
The patient wasn’t covered by this payer on the date of service: CO-26, CO-27, CO-24 (capitation/managed care), CO-109 (wrong payer) and CO-B9 (hospice). CO-31 means the payer can’t identify the patient as one of its members. CO-13 means the date of death on file is earlier than the date of service. PR-24 means a capitation agreement or managed care plan covers the service, filed under patient responsibility. PR-200 means the date of service fell in a lapse in coverage and the amount was assigned to the patient. CO-256 means the service is not payable under a managed care contract.
Coordination of benefits
Another payer may be primary: CO-22, often with MA92 or N598. MA04 comes with CO-16 on secondary claims missing primary payer information. See also OA-23 when the remit shows the impact of prior payer(s) adjudication (COB math, OA group only). See also CO-23 when CARC 23 arrives under group CO, and PR-22 when the coordination-of-benefits reason is filed as patient responsibility. CO-19 means the payer says the injury or illness is work-related, so the workers’ compensation carrier pays first. PR-20 means the payer says a liability carrier covers the injury.
Authorization and precertification
Required prior authorization or notification was missing: CO-197. See also our prior authorization checklist. See also CO-39 when authorization was requested and denied.
Coding, modifiers and bundling
CO-4 (modifier), CO-97 (bundled), CO-236 (NCCI) and CO-11 (diagnosis vs. procedure). CO-B15 means a qualifying service the billed code depends on hasn’t been received or processed. For bundling, see the NCCI PTP table search guide. CO-234 means the procedure is not paid separately and requires a remark code. CO-59 means the line was processed under multiple or concurrent procedure rules (for example multiple surgery or imaging). See also CO-9 (diagnosis vs age) and CO-10 (diagnosis vs gender). For the procedure-code versions of these edits, see CO-5 (place of service), CO-6 (age) and CO-7 (gender). PR-4 is the modifier error filed under patient responsibility, compared with CO-4. PR-11 is the diagnosis-to-procedure match edit filed under patient responsibility, compared with CO-11.
Medical necessity and non-covered services
CO-50 (medical necessity, often with N115 for an LCD) and CO-96 (non-covered). PR-204 (not covered under the patient’s benefit plan) and PR-49 (routine or preventive exam) are usually patient responsibility. See what payers look for in medical necessity documentation. CO-B1 is a non-covered visit; read the remark code for the reason.
Frequency and unit limits
CO-151: the payer says the information doesn’t support this many services or units.
PR-119 / CO-119: the benefit maximum for this time period or occurrence has been reached.
CO-60 covers outpatient services inside the inpatient payment window. CO-39 means services were denied when authorization/pre-cert was requested. CO-307 is the Medicare Maximum Fair Price adjustment. CO-70 is a cost-outlier payment adjustment.
Duplicates
OA-18 (exact duplicate), often paired with N522 on Medicare crossover claims. CO-B13 says the payer believes the claim or service was paid in a previous payment. CO-129 says prior processing information appears incorrect, and it needs a remark code to explain why.
Timely filing
CO-29: the filing limit has passed. Medicare fee-for-service claims generally must be filed within 12 months of the date of service (CMS IOM 100-04, Ch. 1, §70).
Contractual adjustments and patient responsibility (not true denials)
CO-45 (charge above the allowed amount), and PR-1, PR-2 and PR-3 (deductible, coinsurance and copay). See also CO-1, CO-2 and CO-3 when the same CARCs appear with group code CO. OA-1 covers the deductible under group code OA. OA-2 covers coinsurance under group code OA. CO-253 is the Medicare sequestration reduction in federal payment (usually about two percent on FFS). N381 is the alert remark that points you to the contractual agreement (often next to CO-45). MA13 is the alert that you may face penalties for billing the patient for amounts not reported under PR. M5 is a remark about monthly equipment rental limits. N2 is a remark that the allowance followed the plan’s most appropriate course of treatment provision. CO-131 is a claim-specific negotiated discount, for example from a single-case agreement. A dedicated PR-2 page covers coinsurance under group PR.
Provider enrollment and credentialing
CO-B7: the provider wasn’t certified or eligible for the service on that date. PR-242 / CO-242: services were not provided by network/primary care providers.
How to work any denial in 5 steps
- Read the full code set: the group code, every CARC, every RARC, and whether the adjustment is at claim level or line level.
- Work out what you’re dealing with: a rejection, an unprocessable claim or a denial. That decides whether you resubmit or appeal.
- Find the root cause in registration, eligibility, coding, documentation or enrollment.
- Correct and resubmit, or appeal, following the payer’s rules and inside its deadlines. See our corrected claim resubmission guide. and, for Original Medicare, how to appeal a denied Medicare claim.
- Log it and prevent it. Track denials by code, payer and cause, so you can fix the most frequent causes upstream.
Frequently asked questions
What is the difference between a CARC and a RARC? A CARC explains why an amount was adjusted (for example, 16 = missing or invalid information). A RARC adds the detail (for example, N290 = rendering provider identifier missing or invalid). Some CARCs require at least one remark code.
What do CO, PR, OA and PI mean on a remittance? They’re group codes that show who is responsible for an adjustment. CO (Contractual Obligation) is generally a provider write-off. PR (Patient Responsibility) can be billed to the patient. OA is Other Adjustment, and PI is Payor Initiated Reduction.
Can I bill the patient for a CO adjustment? Generally, no. A CO amount is the provider’s write-off under the contract (see the group code table above). Amounts the patient owes are reported under PR.
Is CO-45 a denial? Not in the usual sense. CARC 45 means the charge was above the fee schedule or contracted amount. The difference is a contractual adjustment, not a rejected service.
Can I appeal a Medicare claim returned as unprocessable? No. CMS says a claim returned as unprocessable for incomplete or invalid information “is not afforded appeal rights.” Correct it and submit it again within the timely filing limit.
Where can I find the official, current list of denial codes? X12 publishes the official CARC, RARC and group code lists.
How often are denial codes updated? CMS says the CARC code set is updated three times a year. Each X12 list shows its own update date.