M27 remark code

Remittance advice remark code M27. Remark codes add detail to the reason code on the same claim line.

Patient not liable for the denied service

Unofficial reference. This is our own plain-English explanation, not the official code text. Payer rules differ. Verify with the payer and the official X12 code list. AlphaPrefix is not affiliated with X12, CMS or any payer. Data last updated Nov 11, 2026.

What M27 means

The patient is not held responsible for the denied service, and the provider may owe any amount the patient already paid.

This remark is mostly seen on Medicare claims where a service was found not reasonable and necessary, or was custodial care. The patient did not know and could not be expected to know it would not be covered, so the patient is protected from the charge.

That usually leaves the provider liable. If the patient paid anything, a refund is normally expected. The remark also notes that the provider can appeal.

Common causes

• The service was denied as not medically necessary and no valid advance notice was on file.
• The care was judged custodial rather than skilled.
• An advance notice existed but was not signed, not specific or not given in time.

What to do next

1. Check whether a valid advance notice was given and signed before the service.
2. If the patient paid toward the service, review whether a refund is due under the payer's rules.
3. Appeal with medical records if you believe the service was necessary.
4. Review your advance notice process with front desk and clinical staff.

Related codes

• 50 (reason code) Not medically necessary per the payer
• MA01 (remark code) Alert: how to appeal this decision
• MA13 (remark code) Alert: billing limits on patient amounts