MA13 Remark Code: You May Be Subject to Penalties for Billing the Patient

MA13 is a Remittance Advice Remark Code (RARC) that warns you about billing the patient. A remark code is a message on a remittance that adds detail to a payment or adjustment. X12 labels MA13 an “Alert,” which means it gives information only. It says you may face penalties if you bill the patient for amounts not reported with the PR group code. The CARC and group code on the same line carry the money, so read them first. Many people search for “ma13 remark code”, and that is the phrase this page answers. (Primary sources: X12 Remittance Advice Remark Codes · CMS Claims Processing Manual, Ch. 22, §60.1 · CMS Transmittal 470)

Quick answer: MA13 is a warning, not a denial. Bill the patient only for amounts reported under the PR group code. Post amounts reported under CO or OA as adjustments, and do not send them on a patient statement. Then check the CARC and any paired remark, such as N211 or MA130, to see what to fix.

Part of our denial codes library. Written by Manikandan, a revenue cycle management specialist with more than 10 years of US medical billing experience. Last reviewed: 16 October 2026. Official code wording is quoted word for word from X12; Medicare rules link to their CMS source.

MA13 remark code description (official X12 wording)

X12 Remittance Advice Remark Code MA13, verbatim:

“Alert: You may be subject to penalties if you bill the patient for amounts not reported with the PR (patient responsibility) group code.”

Source: X12 Remittance Advice Remark Codes, checked 16 October 2026. Start: 01/01/1997. Last Modified: 04/01/2007.

What MA13 means in plain English

• It is an alert. It does not change the payment or say why a line was adjusted.
• It is about the group code. Only the PR group marks an amount the patient may owe.
• It protects the patient. An amount under CO or OA is not a bill to the patient.
• The CARC explains the money. MA13 can sit beside many different CARCs.
• It is a posting rule. It tells your staff what must stay off the statement.

Why the group code controls patient billing

CMS Claims Processing Manual Ch. 22, §60.1 defines the groups used on Medicare remits. CO adjustments are “generally… considered a write off for the provider and are not billed to the patient.” PR is used “when the adjustment represent an amount that may be billed to the patient or insured.” OA is used “when no other group code applies to the adjustment.”

CMS Transmittal 470 states the rule directly: “A provider is prohibited from billing a Medicare beneficiary for any adjustment amount identified with a CO group code, but may bill a beneficiary for an adjustment amount identified with a PR group code.” MA13 is the remark that repeats this warning on the remittance.

MA13 vs MA130, N211, N381 and lookalikes

Code	Type	Official idea	Difference
MA13	RARC (Alert)	Penalties for billing the patient for amounts not reported with PR	Patient billing warning. This page
MA130	RARC	Claim has incomplete or invalid information, and no appeal rights because it is unprocessable	Resubmit. See MA130
N211	RARC (Alert)	You may not appeal this decision	No appeal
N381	RARC (Alert)	Consult our contractual agreement	Contract pointer. See N381
CO-45	CARC	Charge exceeds fee schedule or contracted fee	Contract write-off. See CO-45

Where CMS tells contractors to use MA13

CMS instructions name MA13 on specific CO adjustments. Three examples show the pattern.

1. Therapy cap edits. CMS Change Request 8321 (Transmittal 1283, 2013) changed the group code on therapy cap edits from PR to CO. It says contractors use group code CO, CARC 119 and RARC MA13, and only where the GA modifier is not present on the claim.
2. Competitive bidding modifier errors. CMS Change Request 9059 (Transmittal 1482, 2015) says claims returned as unprocessable because of KG, KK, KU or KW modifier misuse carry group code CO, CARC 4, RARC MA13 and RARC MA130.
3. Repair claims under warranty. CMS Change Request 9062 (Transmittal 3196, 2015) says denials for replacement parts and labor on a capped rental item with a warranty use group code CO, CARC 97, RARC MA13 and RARC N211, with the Medicare Summary Notice text “You do not have to pay for this amount.”

These are examples from CMS instructions, not a full list. Payers may use MA13 in other places.

Common triggers for an MA13 line

1. A CO adjustment on a Medicare line. The group code puts the amount on the provider.
2. A claim returned as unprocessable. MA13 may appear with MA130.
3. A denial with no appeal rights. MA13 may appear with N211.
4. A cap or limit edit. The therapy cap example above is one case.
5. A line the patient never agreed to pay. For example, no notice was given, so the amount stays with the provider.

Where MA13 shows up in the 835

CLP*PCN62004*4*150.00*0.00*0.00*12*CLAIM318809~
SVC*HC:E1399*150.00*0.00**1~
CAS*CO*97*150.00~
LQ*HE*MA13~
LQ*HE*N211~

• Status code 4 means the claim was denied.
• The line paid $0.
• CAS*CO*97*150.00 is the adjustment, and the group is CO.
• LQ*HE*MA13 and LQ*HE*N211 carry the remark codes. Some remits use an RMK segment instead.
• This sample is illustrative only. Real remits vary.

How to work an MA13 line: decision path

1. Read the group code and CARC on the same line. Note the amount.
2. Check each amount’s group. Only PR amounts may go on a patient statement.
3. Post CO and OA amounts as adjustments, not as patient balances.
4. Read the other remarks. N211 means no appeal. MA130 means send a new claim.
5. Fix what you can. For an unprocessable claim, correct the data and submit a new claim.
6. If the CARC is a contract matter, compare with your agreement or the fee schedule.
7. If you already billed the patient, reverse the statement and refund anything collected.
8. Train staff to stop patient statements on any line with MA13 and a CO group.

Medicare, commercial and Medicaid notes

Medicare. CMS Transmittal 470 says Medicare providers are prohibited from billing the beneficiary for CO amounts. Medicare Summary Notices may repeat the message in plain words for the patient.

Commercial. The remark text is the same, but billing limits come from your contract and state law. Ask the payer what it means for your agreement.

Medicaid. State programs have their own balance billing rules. Check the state provider manual.

Worked example (illustrative)

A supplier bills $150 for repair parts and labor on a capped rental item. The remit shows CAS*CO*97*150.00 with remarks MA13 and N211.

Reading it: The group is CO, so the supplier carries the amount. MA13 warns against billing the patient, and N211 says the decision cannot be appealed.

Check: The supplier’s file shows the item is under a manufacturer warranty that is still in effect. CMS Change Request 9062 says contractors deny repair claims in that case.

Action: The supplier posts the $150 as a CO adjustment. The supplier does not bill the patient. The supplier sends the repair claim to the manufacturer under the warranty.

Second scenario: The supplier finds that no warranty applies. The supplier asks the DME MAC what correction options exist, since N211 says appeal is not available.

Prevention checklist

• [ ] Split patient statements by group code, so only PR amounts print.
• [ ] Block statement generation on lines with MA13 and a CO or OA group.
• [ ] Teach staff that MA13 is a billing warning, not a payment decision.
• [ ] Review remits that pair MA13 with N211 or MA130.
• [ ] Audit refunds owed on any CO amounts that were billed to patients.
• [ ] Keep the CARC and RARC guide handy for staff training.

Related codes

• MA130: unprocessable claim with no appeal rights.
• N381: consult the contractual agreement.
• CO-45: charge exceeds the fee schedule or contract.
• M5: monthly rental payments.
• CARC and RARC guide.

Key takeaways

MA13 is an alert about patient billing. Bill the patient only for amounts under PR. Post CO and OA amounts as adjustments. Read the CARC and the other remarks to find the fix.

FAQ

Quick facts

Item	Value
X12 RARC	MA13
X12 start	01/01/1997
Last modified	04/01/2007
Type	Alert remark
Official wording	Alert: You may be subject to penalties if you bill the patient for amounts not reported with the PR (patient responsibility) group code
Common confusions	MA130 (unprocessable), N211 (no appeal)
Last reviewed	16 October 2026

Sources

• X12, Remittance Advice Remark Codes (MA13, MA130, N211, N381). MA13 Start 01/01/1997; Last Modified 04/01/2007. Accessed 16 Oct 2026.
• X12, Claim Adjustment Reason Codes (CARC 4, 45, 97, 119). Accessed 16 Oct 2026.
• CMS, Medicare Claims Processing Manual (IOM 100-04), Ch. 22, §60.1 Group Codes. Accessed 16 Oct 2026.
• CMS, Transmittal 470 (4 Feb 2005). Accessed 16 Oct 2026.
• CMS, Transmittal 1283, Change Request 8321 (15 Aug 2013). Accessed 16 Oct 2026.
• CMS, Transmittal 1482, Change Request 9059 (27 Mar 2015). Accessed 16 Oct 2026.
• CMS, Transmittal 3196, Change Request 9062 (13 Feb 2015). Accessed 16 Oct 2026.

Code wording and Medicare rules on this page were checked on 16 October 2026 against X12 and CMS sources.

Last reviewed: 16 October 2026 · This page is educational and doesn’t replace payer-specific contracts or coding rules.