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M39 Remark Code: Advance Notice Invalid, Patient Not Liable

M39 is an alert that the patient cannot be billed for this service. You gave an advance notice of non-coverage, but it did not meet the program's requirements, so liability does not shift to the patient.

Quick facts

Code
M39 (RARC M39)
Status
Active In use since January 1, 1997; last modified July 1, 2015.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The provider absorbs the amount because the notice was defective. Do not bill the patient and refund anything collected.
Official description
Alert: The patient is not liable for payment of this service as the advance notice of non-coverage you provided the patient did not comply with program requirements.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What M39 means

An advance notice of non-coverage only protects the provider if it meets the program’s rules. For Medicare, that means a current approved ABN form, a specific reason the payer is likely to deny, a good-faith cost estimate, and the patient’s signature before the service. M39 says your notice fell short somewhere, so the payer will not treat the patient as liable.

It is common to see M39 on lines billed with the GA modifier when the payer reviewed the notice.

What to do

  1. Stop billing the patient and refund any payment collected for this service.
  2. Review the notice against the program requirements to identify what failed.
  3. Appeal if the notice was compliant, and attach it.
  4. Fix the process: update forms, train staff on timing and specific reasons, and audit completed notices.

M39 is a process failure, not a coverage decision. Patterns of M39, M38, and N563 together show how well your notice workflow performs; see CARC and RARC denial analysis.

Codes that may appear with M39

  • CO-50 (These are non-covered services because this is not deemed a 'medical necessity' by the payer.): The service was not medically necessary, and the defective notice leaves the provider liable.
  • CO-96 (Non-covered charge(s).): The service was non-covered and the notice failed to transfer liability.
  • M38 (Alert: The patient is liable for the charges for this service as they were informed in writing before the service was furnished that we would not…): The notice was valid, so the patient is liable.
  • N563 (Alert: Missing required provider/supplier issuance of advance patient notice of non-coverage.): No advance notice was issued at all.
  • M27 (Alert: The patient has been relieved of liability of payment of these items and services under the limitation of liability provision of the law.): The patient was relieved of liability under the limitation of liability provision.

M39 FAQ

What makes an advance notice invalid?

Common problems include using an outdated form, a generic reason for expected denial, missing cost estimate, no patient signature or date, or giving the notice after the service or under duress.

Can I appeal an M39 finding?

You can appeal if you believe the notice did meet the requirements. Include a copy of the signed notice.

Can I bill the patient anyway?

No. Under M39 the patient is protected. Refund any amount already collected for the service.