CO-198 fires when delivered care exceeds the quantity authorized — visits, units, days or dollars. The authorization was valid; the volume was not covered by it.
What CO-198 means
Authorizations are granted for a specified quantity, and clinical courses do not always fit inside them. The failure is usually one of timing rather than judgement: nobody requested an extension while the course was running. Most payers will consider a concurrent extension readily and a retrospective one reluctantly, which makes tracking authorized quantities against delivered ones an operational safeguard rather than a billing task.
Why CO-198 fires
- More visits or units were delivered than the authorization covered.
- An inpatient stay ran past the approved days without a concurrent review.
- The authorized quantity was consumed by earlier claims in the course.
- A separate service was billed against the same authorization.
Is CO-198 worth appealing?
Sometimes worth appealing
How to resolve or appeal CO-198
- 1
Reconcile authorized against delivered
Confirm the exceedance is real before appealing — earlier claims may have consumed the units.
- 2
Request a retrospective extension
With the clinical justification for the additional quantity.
- 3
Show what changed
An extension is granted on evidence that the course required more, not that more was given.
CO-198 — frequently asked
Should I have requested an extension earlier?
Can the patient be billed for the excess?
Reason-code meanings are paraphrased from the X12 Claim Adjustment Reason Code list for plain-language reference; they are not reproduced verbatim. This is general information, not legal, coding, or medical advice — always confirm against the payer's remittance and policy.
Turn this CO-198 denial into a signed appeal
Upload the denied EOB and Merits builds a complete CO-198 appeal — the argument, the payer's own coverage criteria, and your federal appeal rights, every claim cited to a named source. $9 a letter. No account.