Denial Code Decoder

CO-197 — No authorization on file

The payer required approval before this service and has no record that it was obtained. Whether the money is recoverable turns on a question the denial does not answer: was an authorization actually secured and simply not carried on the claim, or was it never obtained at all? Those are a clerical fix and a policy argument respectively, and they are worked nothing alike.

Billable to the patient? Usually not. Under most participating contracts a missing authorization is a provider-side failure and the balance may not move to the patient — but that answer lives in your contract, not on the remittance, so read it before anyone is sent a statement.

Replaced code 15

Authorization denials used to arrive as code 15. Anything written about 'CO-15' since then is describing a code no payer can send, which is why this page carries the number you will actually see. X12 stopped code 15 on May 1, 2018.

Where it strikes

Where this denial is born

Front desk
Coding
Claim build
Submission
Adjudication

This denial is usually created at the highlighted stage — that is where prevention lives.

Work the denial

Answer the questions — follow the path

The same questions an experienced biller asks, in order. Your answers draw the route to the right action.

Was an authorization obtained before the service?

Check the scheduling record and the payer portal, not just the chart — approvals are often logged outside the clinical note.

Every path

The full decision tree

Was an authorization obtained before the service?

Check the scheduling record and the payer portal, not just the chart — approvals are often logged outside the clinical note.

Yes →
Does the authorization on file actually cover what was performed?
Compare the approved codes, units and date range against the claim. An approval that expired, or that names a different procedure, is not a match.
- Yes →
  Appeal with the approval attached. Send the authorization number, its date range and the approved codes, and ask for reprocessing. This is the strongest version of this appeal, because it disputes a fact rather than a judgment.
- No →
  Work the gap between what was approved and what was done. If the service outgrew its approval — extra units, a changed procedure, a date past the window — the argument is clinical, not clerical. Build it from the record and the plan's own criteria, and expect to need the treating provider.
No →
Does the payer accept a retroactive authorization request in this situation?
Many plans allow one for urgent or emergent care, or where eligibility was established after the fact. The plan's own policy decides.
- Yes →
  Request the retroactive authorization. File it the way the plan specifies and inside the window the plan allows, then resubmit once it is granted. Note the request reference — a later appeal will need to show it was made.
- No →
  Resolve liability, then fix the schedule. With no authorization and no retroactive path, the balance usually stays with the practice. The recoverable value here is upstream: find how the service got scheduled without the requirement being checked.

Stop the repeat

Prevention

Check authorization requirements at scheduling rather than at check-in. Once the patient is in the building the only choices left are to delay their care or to absorb the denial, and neither is a good day.

Go deeper

The code list, and when it was last checked

X12 maintains the Claim Adjustment Reason Codes list, where this code is listed as 197. The list carries the number alone: the CO in front of it is the adjustment group the payer chose for this line, which decides who owes the balance, and the same code can arrive under a different group from a different payer. It has been on the list since October 31, 2006, and X12 last revised its entry on May 1, 2018.

Checked against the list revision dated November 1, 2025 on August 7, 2026, where it reads as an active code.

X12 — Claim Adjustment Reason Codes (opens in a new tab)

Check the reasoning