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MA13 Remark Code: Penalty Warning for Patient Billing

MA13 is an alert warning that you may be subject to penalties if you bill the patient for amounts that were not reported under the PR (patient responsibility) group code. Only PR amounts on the remittance may be collected from the patient.

Quick facts

Code
MA13 (RARC MA13)
Status
Active In use since January 1, 1997; last modified April 1, 2007.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): Amounts under CO are the provider's responsibility. MA13 underlines that billing these to the patient may carry penalties.
  • PR (Patient Responsibility): These are the only amounts the patient may be billed for on this claim.
Official description
Alert: You may be subject to penalties if you bill the patient for amounts not reported with the PR (patient responsibility) group code.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What MA13 means

Group codes on a remittance decide who owes each adjusted amount. CO means the provider is responsible under contract or regulation; PR means the patient is. MA13 is a pointed reminder from the payer, usually Medicare, that collecting anything outside PR from the patient may expose you to penalties.

It appears most often when a line carries a CO adjustment that could tempt a practice to transfer the balance to the patient, such as a denied service without a valid advance notice.

What to do

  1. Separate CO and PR balances when posting the remittance.
  2. Bill the patient only for PR. Write off or dispute CO amounts, never transfer them to the patient.
  3. Check statements already sent. If a patient was billed for a CO amount, correct the statement and refund any payment.
  4. Review advance notice practices if CO denials for non-covered services recur, since valid notices determine when a patient can be held liable.

Understanding group codes is covered in how to read CARC and RARC codes.

Codes that may appear with MA13

  • CO-45 (Charge exceeds fee schedule/maximum allowable or contracted/legislated fee arrangement.): A fee schedule reduction under CO that must not be passed on to the patient.
  • CO-50 (These are non-covered services because this is not deemed a 'medical necessity' by the payer.): A medical necessity denial under CO, typically when no valid advance notice shifted liability to the patient.
  • CO-97 (The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.): A bundled service under CO that the patient cannot be billed for.
  • MA10 (Alert: The patient's payment was in excess of the amount owed.): The patient overpaid, and the excess must be refunded.
  • MA59 (Alert: The patient overpaid you for these services.): A patient overpayment alert with a 30-day refund window.
  • MA26 (Alert: Our records indicate that you were previously informed of this rule.): An alert that you were previously informed of the rule applied.

MA13 FAQ

Which amounts can I bill the patient for?

Only those reported with group code PR, such as deductible, coinsurance, and co-payment, plus non-covered amounts that were properly assigned to the patient.

What if I think the patient should owe a CO amount?

Contest the determination with the payer through a reopening or appeal. Do not bill the patient while the amount is reported under CO.

Does MA13 mean I already did something wrong?

No. It is a standing warning attached to the remittance. It becomes a problem only if CO balances are transferred to the patient.