CO-197 denial code
No prior authorization. The payer required precertification for this service and cannot find one — either it was never obtained, or it was obtained and the claim doesn't show it. Among the most expensive denials there is, and one of the most appealable.
CO — Contractual Obligation. The write-off is yours. You agreed to it in your contract with the payer, and you cannot bill the patient for it.
Why you got it
- 1Authorization genuinely was never requested — the service wasn't on anyone's list of things that need it, or the requirement was added recently.
- 2An authorization exists but the number never made it onto the claim.
- 3The authorization doesn't match the claim: different procedure, different date range, different rendering provider or site, or the approved units ran out.
- 4The authorization expired before the service happened, often because scheduling slipped.
How do I fix a CO-197 denial?
- If an authorization exists, this is the easy version: resubmit or appeal with the authorization number and the approval letter. Mismatches (date, provider, units) go to the payer with an explanation of the discrepancy.
- If it was never obtained, ask about retroactive authorization immediately — many payers allow it in a narrow window, and 'immediately' is the operative word for urgent or add-on services.
- If retro-auth is refused, appeal on the merits: why the service was needed, why obtaining authorization first wasn't possible (urgent finding, service added intraoperatively), and the clinical documentation. Payers overturn more of these than they advertise.
Writing the appeal?
Our free generator drafts a CO-197 appeal letter that opens with the argument above — it runs entirely in your browser, so the claim details never leave your screen. No signup.
Generate the appeal letterHow to stop the next one
Make authorization a scheduling gate, not a billing discovery. Track four things per auth: the number, the exact codes approved, the date window, and the units — a mismatch on any one of them lands you back on this page.
Our diagnosis scrubber will not catch this one. CO-197 is driven by procedure codes, modifiers, or eligibility rather than by the diagnosis set — and procedure-side checking needs CPT codes, which aren’t included yet. We would rather tell you that than sell you a tool that quietly misses your most common denial.
If denials like this are a volume problem rather than a one-off, the denial management page explains how the paid workspace catches the coding causes on every claim, and the free ICD-10-CM lookup shows the coding notes behind any diagnosis code on the remittance.