How do I resolve a CO-15 denial?

Log into the payer's provider portal and look up the authorization by patient name and date of service. Compare the auth number in the portal to the number submitted on the claim — check for transpositions, extra characters, or format differences. Confirm the auth covers the correct provider, procedure code, and date of service. If the auth number is correct but invalid, contact provider services to determine if the auth needs to be reissued. Resubmit the claim with the corrected or reissued authorization number.

Can I appeal a CO-15 denial?

Yes. CO-15 denials are typically appealable with a 85% success rate. Resolution difficulty is Easy and typically takes 5-10 days.

835 Denial Combination

CO-15

Contractual Obligation · Claim-Level Adjustment

What This Combination Means

The authorization number on the claim is invalid — it does not match the payer's records. This could mean the auth number was transposed, the auth was issued for a different provider or plan, or the auth has expired. It is often correctable by locating and resubmitting with the correct auth number.

85%

Appeal Success

5-10 days

Avg. Resolution

Easy

Difficulty

Yes

Appealable

Step-by-Step Resolution

Steps tailored specifically to this CO-15 combination — not generic advice.

1
Log into the payer's provider portal and look up the authorization by patient name and date of service.
2
Compare the auth number in the portal to the number submitted on the claim — check for transpositions, extra characters, or format differences.
3
Confirm the auth covers the correct provider, procedure code, and date of service.
4
If the auth number is correct but invalid, contact provider services to determine if the auth needs to be reissued.
5
Resubmit the claim with the corrected or reissued authorization number.

Specialty Context

How CO-15 typically presents across different practice types.

Dental

Auth numbers from predeterminations sometimes change when a plan year renews. Confirm the auth number is from the current plan year and has not expired.

Medical

Auth numbers are case-sensitive and format-sensitive. A hyphen, leading zero, or extra digit can cause this denial. Confirm the exact format from the authorization letter or portal.

Behavioral Health

MBHO auth numbers differ from the medical auth system. Confirm the auth was obtained from the correct entity (the MBHO, not the medical plan) and the number matches exactly.

Individual Code References

View the standalone definition for each code in this combination.

CARC 15

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