What is denial code CO-198?
CO-198 means an authorization existed, but the service went beyond it: more units or visits, a longer period, or a different service than the payer approved.
Remittance advice, claim line
- Authorization
- AUTH77310, 12 visits, Jan 5 to Mar 5
- Date of service
- 03/09/2026
| Service | Billed | Paid | Adjustment | Remark |
|---|---|---|---|---|
| 97110 Therapeutic exercise, 2 units | $140.00 | $0.00 | CO-198 $140.00 | N54 |
- Visit 13, four days after the authorization ended. The payer approved 12 visits through March 5.
- Next step: request an extension or a new authorization covering the date, then send a corrected claim. Without one, appeal if the visit was necessary.
The full description of reason code 198 is Precertification/notification/authorization/pre-treatment exceeded. Unlike CO-197, the authorization exists; the claim just doesn’t fit inside it.
Common causes
- More units or visits billed than were approved.
- The service happened after the authorization expired.
- The billed code, provider or site differs from the one authorized.
How to resolve and prevent it
Compare the authorization line by line with the claim. If the payer recorded it wrong, a call or a corrected claim fixes it; if the service truly went past it, request an extension or retro-authorization where the payer allows. Prevention is tracking: watch units used and expiry dates on every open authorization, and start the extension before the last approved visit.
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