Denial code CO-15: Authorization number missing or invalid
An authorization was required and one was obtained, but the number submitted does not match what the payer has on file for these services or this provider.
The authorization number is missing, invalid, or does not apply to the billed services or provider.
What CO-15 actually means
CO-15 is distinct from CO-197 in a way that matters commercially: with CO-197 no authorization exists, while with CO-15 one usually does — it just was not transmitted correctly, or it does not cover exactly what was billed. That makes CO-15 one of the most recoverable denial types in the book, because the underlying approval already exists and only the claim needs to be fixed.
Why this denial happens
- The authorization number was omitted from the claim or keyed with a transposition.
- The authorization covers a different procedure code, unit count, or date range than what was billed.
- The authorization was issued to a different rendering provider or facility.
- Services continued past the authorized date span without an extension.
How to resolve a CO-15 denial
- Retrieve the authorization record and compare the number, procedure codes, unit count, provider, and date span line by line against the claim.
- Correct whichever field diverges and resubmit as a corrected claim.
- If the service legitimately exceeded the authorized scope, request a retro-authorization or extension before appealing.
How to prevent it
- Store the authorization number, covered codes, unit count, and date span in the patient record, not in a spreadsheet or an inbox.
- Reconcile authorized units against delivered units before the authorization expires, not after.
Frequently asked
What does denial code CO-15 mean?
An authorization was required and one was obtained, but the number submitted does not match what the payer has on file for these services or this provider. The X12 description reads: "The authorization number is missing, invalid, or does not apply to the billed services or provider."
How do I fix a CO-15 denial?
Retrieve the authorization record and compare the number, procedure codes, unit count, provider, and date span line by line against the claim. Correct whichever field diverges and resubmit as a corrected claim. If the service legitimately exceeded the authorized scope, request a retro-authorization or extension before appealing.
Can CO-15 be billed to the patient?
Generally no. The recommended path for this code is "appeal or correct and resubmit" — check your payer agreement before transferring any balance to the patient.
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General revenue-cycle guidance, not legal, coding, or payer-specific advice. Claim adjustment reason codes are maintained by X12 and are revised periodically; payer policy and your provider agreement govern in any specific case. Always read the remark codes transmitted with the denial — they frequently carry the detail this code does not.