Medicare Denied: No Prior Authorization (Your Fix)

What This Means

Your claim was denied because the service required prior authorization — your plan’s advance approval — and none was on file; getting that approval is almost always your provider’s responsibility, not yours. On your notice this appears as CARC code CO-197, “precertification/authorization/notification/pre-treatment absent”. Do one thing now: call your provider’s billing office and ask them to request retroactive authorization from your plan — some plans allow it, especially in urgent situations, and it can clear the denial without a formal appeal. Pursue that alongside your appeal, not instead of it: no rule caps how long a plan may sit on a retroactive request, and waiting on one does not pause your appeal clock. You have 65 days from the date on your denial notice (Medicare Advantage) or 120 days from receiving your MSN (Original Medicare), and 80.7% of appealed Medicare Advantage prior authorization denials were fully or partially overturned in 2024.

Already had an approval? If your provider obtained the authorization but the number never made it onto the claim, this is a billing correction, not an appeal: ask the billing office to verify the authorization number and resubmit the claim.

Not sure this is your situation? Authorization denials come in several forms, and each has its own guide:

• Did your plan review the authorization request and deny it? See prior authorization request denied.
• Was an authorization approved but expired, used up, or mismatched with the service billed? See prior authorization expired.
• Does the denial point to a missing referral from your primary care doctor? See referral missing or invalid.

This denial doesn’t mean the service wasn’t needed. It means the required administrative step of getting the plan’s approval in advance was missed — one of the most common reasons for Medicare Advantage claim denials. Original Medicare, by contrast, requires prior authorization for very few services.

Why This Happens

• Your provider didn’t request prior authorization. Some services require advance approval from your plan. If your provider didn’t submit the request before providing the service, the claim can be denied.
• The authorization request was incomplete or never processed. Your provider may have started the authorization process but didn’t complete it, or the request was lost in the system.
• The authorization number wasn’t included on the claim. The provider obtained authorization but didn’t put the authorization number on the claim form when billing.
• The service was provided on an emergency basis. Emergency services generally don’t require prior authorization, but follow-up care or non-emergency services provided during the same visit might.
• You’re in a Medicare Advantage plan. MA plans require prior authorization far more often than Original Medicare. In 2024, Medicare Advantage insurers made nearly 53 million prior authorization determinations, according to KFF.

Should You Appeal?

What To Do Next

1. Contact your provider’s office immediately. Ask them if they can request retroactive authorization from your plan. Some plans allow this, especially for urgent situations, and it can resolve the denial without a formal appeal.
2. Check whether the authorization was actually obtained. It’s possible your provider got the authorization but forgot to include the number on the claim. Ask the billing office to verify and resubmit if needed.
3. File the appeal without waiting on that answer. A retroactive-authorization request has no response deadline, and pursuing it does not pause your 65-day (Medicare Advantage) or 120-day (Original Medicare) appeal clock — file inside your window and withdraw the appeal if the authorization comes through. Follow the instructions on your denial notice, and ask your provider to include a letter explaining why the service was medically necessary.
4. Keep records of everything. Save your denial notice, any correspondence with your provider or plan, and notes from phone calls (including dates, names, and what was discussed).
5. For Medicare Advantage plans, know the decision clocks: when the appeal is about paying for a service you already received, the plan has up to 60 days to decide, and that window cannot be extended; a standard appeal for a service you haven’t gotten yet must be decided within 30 days (42 CFR 422.590). The 72-hour expedited track is not available for a denial like this one — 42 CFR 422.584(a) excludes requests for payment of services already furnished — so plan for the 60-day timeline and keep following up in writing.

Sources

• KFF: Medicare Advantage Insurers Made Nearly 53 Million Prior Authorization Determinations in 2024 — nearly 53 million determinations in 2024; 80.7% of appealed denials fully or partially overturned; only 11.5% of denials appealed
• OIG: Some Medicare Advantage Organization Denials of Prior Authorization Requests Raise Concerns About Beneficiary Access to Medically Necessary Care (2022) — 13% of denied prior authorization requests met Original Medicare coverage rules
• Medicare.gov: Filing an Appeal
• Medicare.gov: Appeals in Medicare Health Plans — the 65-day filing deadline and the 30-day service / 60-day payment / 72-hour expedited decision timeframes
• 42 CFR 422.590 — the plan’s reconsideration deadlines: 60 calendar days for a request for payment (the track a post-service denial like this one falls on), 30 calendar days for a request for a service or item; (f) extends service or item requests only
• 42 CFR 422.584 — who may request an expedited reconsideration; expressly excludes requests for payment of services already furnished, which is why the 72-hour track is unavailable on a post-service denial like this one
• CMS Innovation Center: WISeR (Wasteful and Inappropriate Service Reduction) Model — prior authorization testing in Original Medicare, January 1, 2026 through 2031, in six states
• X12: Claim Adjustment Reason Codes (CARCs) — official definition of CO-197

Frequently Asked Questions