Denial Codes

A denial code is the standardized reason a payer gives for not paying all or part of a claim line. It appears on the 835 electronic remittance or paper EOB as a Claim Adjustment Reason Code (CARC), paired with a group code such as CO, PR, or OA and often a Remittance Advice Remark Code (RARC).

This category is for billers, coders, and AR follow-up staff who need more than a one-line definition. Each article covers one denial in depth: what triggers it, how payers apply it, and the steps to correct, appeal, or prevent it. Start with the CO-97 bundling denial guide, then use the NCCI PTP table lookup walkthrough to check whether a code pair is actually bundled. For prevention, see clearinghouse NCCI scrubbing setup and building a CO-97 denial tracking dashboard. Coverage and authorization denials are covered in CO-96 non-covered charges and CO-197 criteria at three commercial payers.

For a quick code-by-code reference, use the denial codes lookup page; this archive holds the full articles behind it.

Denial Code FAQs

What is the difference between CO and PR denials?
CO (Contractual Obligation) means the adjustment is the provider’s responsibility under the payer contract, so the patient cannot be billed for it. PR (Patient Responsibility) means the amount can be billed to the patient, such as a deductible, coinsurance, or copay. The same CARC can carry either group code.

Should every denial be appealed?
No. Many denials are fixed faster with a corrected claim, such as a missing modifier, a wrong diagnosis pointer, or a demographic error. Appeals fit when the claim was correct and the payer misapplied a policy or edit. Check the CARC, RARC, and payer policy first, then choose the route.