CO-198 Denial Code: Precertification/Notification/Authorization Exceeded
CO-198 is a claim adjustment reason code meaning precertification, notification, authorization, or pre-treatment limits were exceeded: an approval exists, but you billed more visits, units, or days than it allowed. The fix is an authorization extension or an appeal showing the additional services were medically necessary.
- Group
- CO (Contractual Obligation)
- Category
- Authorization limits exceeded
- Appealable?
- Yes; extension requests and medical necessity appeals
- Typical fix
- Request auth extension/additional units, rebill approved services
What does denial code CO-198 mean?
CO-198 means "precertification/notification/authorization/pre-treatment exceeded." The payer's utilization management department approved a defined amount of care, and the claim went past it: visit 13 on a 12-visit auth, units above the approved count, or a date of service after the auth's end date. Everything inside the approval paid; the overage did not.
Example: an outpatient PT clinic holds auth 78Q4432 approving 12 visits through June 30. The patient improves slowly and the therapist schedules visits 13 and 14 in early July. ERA for visit 13: 97110/97140 billed $178.00, allowed $0.00, CO-198 $178.00, paid $0.00, remark N54 or N351. Both the visit count and the date window were blown, and no extension request was ever filed.
Why did the claim get a CO-198?
- No one tracked the countdown. The auth's visit and unit limits were not decremented in the scheduling system, so care sailed past the cap unnoticed.
- Extension requested too late or never, even though the clinical need was documented all along.
- Date window expired after rescheduling, hospitalization gaps, or patient no-shows stretched the episode past the auth end date.
- Units per visit misunderstood: the auth approved 12 visits, but the payer counts units, and billing 4 units per visit exhausted it by visit 6 (or vice versa).
- Intensity changes, like adding a new modality or code not in the original approval.
How do you fix and resubmit a CO-198 denial?
- Pull the auth and establish exactly what was approved: visits, units, codes, and date range. Then map every billed date against it so you know which lines are truly overage.
- Call UM and request a retro extension or additional units for the overage dates, armed with progress notes showing measurable improvement and continued medical necessity.
- If the payer grants the extension, resubmit the denied claims referencing the updated auth.
- If it refuses, file a medical necessity appeal for the overage visits; do not touch the paid visits.
- Going forward on this patient, get the next extension request in before the current approval runs out.
How do you prevent CO-198 denials?
Track every active authorization as a countdown in the PM system: units remaining, visits remaining, and end date, visible at scheduling and check-in. Reconcile billed units against approved units weekly for therapy and infusion services, where unit-versus-visit confusion is endemic. Confirm whether the payer counts visits, units, or dollars at the moment the auth is issued, and calendar the end date with a two-week warning. Clinics that operationalize the countdown routinely push auth-related denials below 1 percent of claims.
Can you appeal a CO-198 denial?
Yes, and the winning theme is continuity of medically necessary care: show objective progress data, the treatment plan, and why stopping at the authorized limit would have harmed the outcome, then tie it to the payer's own continued-stay or extension criteria. Attach proof of any timely extension request the payer sat on; delayed UM decisions are strong appeal material. Verify the filing window with the appeal deadline calculator, assemble the packet with the appeal letter generator, and confirm the remark codes in the denial code lookup so you can tell an exceeded-units denial from an expired-window one; they argue differently.
Frequently asked questions
An authorization existed, but the claim went beyond it: more visits than approved, more units than approved, or dates past the authorized window. The payer paid nothing on the excess because the approval it issued was used up. It is the "auth ran out" cousin of CO-197's "no auth at all."
CO-119 is a benefit design cap: the plan itself only covers, say, 20 therapy visits a year. CO-198 is an authorization cap: utilization management approved 12 visits and you billed 14. A patient can hit CO-198 with plenty of benefit remaining, and fixing it means extending the auth, not arguing benefits.
Usually yes, through a concurrent review or extension request with updated clinical documentation showing progress and continued need. Timing is critical: requests submitted before the last approved visit routinely succeed, while requests after services were already delivered face retro-review and much worse odds.
Sources & further reading
Reviewed by the ImmediCare Solutions RCM team
Certified billers and coders handling claims across 50+ specialties nationwide. This entry is reviewed against current payer policy and CMS rules. Last review: Jul 5, 2026.
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