What is denial code CO-197?
CO-197 means the payer denied the service because a required prior authorization, precertification or notification wasn't on file. The provider can't bill the patient for it.
Remittance advice, claim line
- Payer
- Example Health Plan
- Patient
- Jordan Sample
- Claim number
- 2026020310442
- Date of service
- 02/03/2026
| Service | Billed | Allowed | Paid | Adjustment | Remark |
|---|---|---|---|---|---|
| 72148 MRI lumbar spine | $1,450.00 | $0.00 | $0.00 | CO-197 $1,450.00 | M62 |
- CO is the group code: contractual obligation. The provider owns this balance, so the patient can't be billed for it.
- 197 is the reason: the payer has no precertification, authorization or notification on file for this service.
- Remark M62 adds that the treatment authorization code on the claim was missing, incomplete or invalid.
- Next step: check whether an authorization exists. If it does, send a corrected claim with the number. If it doesn't, ask about a retro-authorization or appeal.
CO-197 is one of the most common front-end denials. The full description of reason code 197 reads: Precertification/notification/authorization/pre-treatment absent. The group code CO, contractual obligation, puts the loss on the provider.
Common causes
- No authorization was requested before the service.
- An authorization exists, but its number never made it onto the claim.
- The authorization covers a different code, date range, provider or site. That usually comes back as CO-198 or with remark N54, but some payers use 197.
- The authorization expired, or its units ran out before the service.
How to resolve it
- Look for an authorization on file. Check the payer portal and your own records before anything else.
- If it exists, send a corrected claim with the authorization number.
- If it doesn’t, ask whether the payer allows a retro-authorization, or appeal with the records that show the service was necessary and urgent.
- Watch the clock. The corrected-claim window and the appeal window start with the denial, and they’re often shorter than you think.
How to prevent it
Most CO-197s are decided at intake. Check whether each payer, plan and code needs prior authorization before the service, track every authorization’s expiry and units, and make sure its number travels onto the claim.
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