M79 remark code

Remittance advice remark code M79. Remark codes add detail to the reason code on the same claim line.

Missing or invalid line charge

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 M79 means

The charge on a service line is missing, zero or not valid, so the payer could not process it.

Each line needs a charge amount. This remark says a line had no charge, a zero charge where one was required, or an amount in an unusable format.

It typically comes with reason code 16. A corrected claim with the right amount normally fixes it.

Common causes

• The fee schedule in the billing system had no charge for the code.
• The charge was entered as zero for an item that should have a charge.
• A formatting or rounding problem in the claim file corrupted the amount.

What to do next

1. Check the line charge against your fee schedule for the code.
2. Add the missing charge to the fee schedule so the error does not repeat.
3. Resubmit a corrected claim and confirm the total still matches the lines.

Related codes

• 16 (reason code) Missing information or billing error
• M54 (remark code) Missing or invalid total charges