Official CARC description: “The authorization number is missing, invalid, or does not apply to the billed services or provider.” Here’s what it actually means, why it fires, and how to get the claim paid.
An auth number is on the claim but doesn't match — wrong format, wrong provider, wrong CPT, or wrong dates. Sibling of CO 197 with a data-matching flavor.
Liability group: CO = Contractual Obligation — the provider absorbs it — the amount cannot be billed to the patient. If the denial is wrong, the money is recovered by correcting or appealing the claim, not by balance-billing.
Also written: CO-15, CO15, “denial code 15”, “15 denial code” or “reason code 15” — same CARC, different ERA formatting.
Pull the auth from the portal; compare every field to the claim
Simple mismatch: corrected claim with aligned data
CPT changed intra-procedure: request an auth amendment with the op note
Group/rendering NPI issues: ask the payer which NPI the auth binds to
Appeal with the auth documentation when the service was genuinely authorised — payers hold these to matching rules their own reps often misquote. Get the binding rules in writing.
Fill in the denial facts — use placeholders, never real patient data (the letter keeps [PATIENT NAME]-style fields so you can merge real details privately). A payer-ready draft with an enclosure checklist comes back in ~20 seconds.
Your appeal letter draft will appear here.
The official CARC description for CO 15 is: “The authorization number is missing, invalid, or does not apply to the billed services or provider.” In practice: An auth number is on the claim but doesn't match — wrong format, wrong provider, wrong CPT, or wrong dates. Sibling of CO 197 with a data-matching flavor.
Denial code 15 under the CO group (Contractual Obligation) means: The authorization number is missing, invalid, or does not apply to the billed services or provider. The number is the reason; the CO prefix decides who is liable — the provider absorbs it — the amount cannot be billed to the patient. If the denial is wrong, the money is recovered by correcting or appealing the claim, not by balance-billing.
Yes. CO 15, CO-15, CO15 and “denial code 15” are the same CARC — clearinghouses, payer portals and PM systems just print it differently. Only the group prefix (CO, PR, OA or PI) changes the meaning, because it changes who has to absorb the amount.
CO stands for Contractual Obligation — the provider absorbs it — the amount cannot be billed to the patient. If the denial is wrong, the money is recovered by correcting or appealing the claim, not by balance-billing.
Appeal with the auth documentation when the service was genuinely authorised — payers hold these to matching rules their own reps often misquote. Get the binding rules in writing.