Medicare Denied Claim: Prior Authorization Expired

What This Means

Your claim was denied because the prior authorization on file either expired before the service was provided or didn’t match the service that was actually performed. On your notice this usually appears as CARC CO-15 (authorization “missing, invalid, or does not apply to the billed services”) or CO-198 (authorization “exceeded”). Even though your plan originally approved something, the approval wasn’t valid for what was ultimately billed.

This is a common issue when there are scheduling delays or when the service delivered differs from what was originally authorized.

Why This Happens

• The authorization expired before your appointment. Prior authorizations have an expiration date. If your appointment was delayed beyond that date, the authorization is no longer valid. Common validity periods range from 30 to 90 days.
• The service performed was different from what was authorized. If the surgeon authorized a procedure on your left knee but operated on your right knee, or if a different procedure was performed than what was approved, the authorization won’t match.
• The claim used different billing codes than the authorization. Even if the service was the same, a mismatch between the CPT or HCPCS codes on the authorization and the claim can cause a denial.
• More units or sessions were provided than authorized. If your authorization covered 6 physical therapy visits but you had 8, the extra visits may be denied.
• The service was provided by a different provider. Some authorizations are specific to a particular provider. If you saw a different doctor or went to a different facility, the authorization may not apply.
• Administrative delays in scheduling. Long wait times for specialist appointments or surgical scheduling can push the service date past the authorization expiration.

Should You Appeal?

What To Do Next

1. Contact your provider’s billing office. Ask them to review the authorization details and the claim. If the issue is a coding mismatch, they may be able to correct the claim and resubmit it.
2. Check the authorization letter. Review the expiration date, approved services, and any conditions listed. This will help you understand exactly why the claim didn’t match.
3. Ask your provider to request a new authorization if needed. For future services, a new prior authorization can be obtained. For the already-denied service, you’ll need to appeal.
4. If you appeal, document the timeline. Show when the authorization was issued, when you tried to schedule the service, and why there was a delay. Include any evidence that the delay was outside your control (appointment wait lists, cancellation notices, etc.).
5. For Medicare Advantage plans, note that under CMS rules in effect since 2024 (42 CFR 422.138), an approved authorization must remain valid for as long as medically necessary to avoid interrupting an active course of treatment, with at least a 90-day carryover when you switch plans. If your plan cut short an authorization for ongoing treatment, this rule may help your appeal.

Sources

• eCFR — 42 CFR 422.138: Prior authorization — an approved MA authorization stays valid for the active course of treatment and can’t be reopened except for good cause or fraud
• Federal Register — CY2024 Medicare Advantage Final Rule (CMS-4201-F) — added the continuity-of-care / authorization-validity protections effective 2024, including the 90-day carryover on plan switches
• Medicare.gov: Filing an Appeal
• CMS: Reconsideration by the Medicare Advantage (Part C) Health Plan — the MA Level-1 appeal process
• X12: Claim Adjustment Reason Codes — definitions of CO-15 and CO-198

Frequently Asked Questions