How to Appeal a Medicare Advantage Prior Authorization Denial

Prior authorization is the requirement that your Medicare Advantage plan approve certain procedures, specialist visits, hospital admissions, or medications before you receive them. When a plan denies that authorization, it can feel like a dead end. It is not. Medicare law gives you a structured appeals process with specific timeframes the plan must meet, and appeals succeed at a meaningful rate. Understanding how to navigate a denial before you are in crisis is the most valuable preparation you can do as an Advantage plan enrollee.

Bryce's Take

Every week someone tells me they were denied and do not know what to do next. The appeal process works more often than people expect, especially when the physician writes a strong medical necessity letter that directly addresses the denial reason. The peer-to-peer review, your doctor calling the plan's medical director, resolves more denials than formal appeals data shows, because those calls never get logged as appeals.

What prior authorization is and why plans require it

Prior authorization, or PA, is a pre-service approval requirement built into Medicare Advantage plan designs. Plans require it for services they consider potentially unnecessary, expensive, or subject to overuse. Common PA requirements include inpatient hospital admissions, post-acute care like skilled nursing and home health, certain imaging (MRIs, CT scans), specialist referrals, non-urgent surgeries, and many specialty drugs. CMS issued new rules in 2024 requiring Advantage plans to reduce unnecessary PA requirements, respond faster to PA requests, and make their PA criteria publicly available.

The difference between a coverage determination and a prior authorization

A coverage determination is a formal decision by your plan about whether a service or drug is covered. Prior authorization is one type of coverage determination, a pre-service decision. You can also request a coverage determination after the fact if you received a service and need a payment decision. Both types of determinations follow the same appeals structure and timeframes. All denials must be provided in writing with an explanation of why coverage was denied and your appeal rights.

Level one: Redetermination by the plan

The first appeal level is a redetermination request to your Medicare Advantage plan. For standard requests, the plan must respond within 60 days for post-service claims and 30 days for pre-service coverage decisions. For expedited requests (when the standard timeline would seriously jeopardize your health), the plan must respond within 72 hours. To request expedited review, have your physician document why faster processing is medically necessary. Submit your redetermination request in writing, include supporting clinical documentation, and get your physician to submit a letter of medical necessity specifically citing clinical guidelines that support coverage.

Level two: Independent Review Entity

If the plan upholds the denial, you can appeal to an Independent Review Entity or IRE contracted by CMS. The IRE is independent of your plan and makes its own coverage determination. The IRE timeframe is 60 days for standard appeals and 72 hours for expedited. Include all documentation from your prior appeal plus any new clinical evidence. IRE appeals succeed at higher rates than plan-level redeterminations because the IRE applies Medicare coverage rules directly rather than the plan's internal criteria.

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Levels three through five

If the IRE upholds the denial, further appeal goes to the Office of Medicare Hearings and Appeals (OMHA), where an administrative law judge reviews the case. OMHA has a 90-day timeframe for standard cases. Above OMHA is the Medicare Appeals Council (MAC), and above that is Federal District Court. Relatively few cases reach OMHA or beyond, but the option exists and has produced meaningful precedents. An attorney or patient advocacy organization can be helpful at these higher levels.

Building a strong appeal from the start

The single most important factor in a successful appeal is clinical documentation. Your physician's letter of medical necessity should cite specific clinical guidelines (ACC/AHA guidelines for cardiac procedures, NCCN guidelines for oncology, etc.), explain why the requested service is medically necessary for your specific condition, and directly address the reason given for the denial. Generic letters rarely succeed; specific, documented, guideline-based letters do much better. Keep copies of everything you submit and request tracking numbers for your appeals.

Frequently asked questions

How long do I have to appeal a Medicare Advantage denial?

For a plan-level redetermination, you generally have 60 days from the date of the denial notice. Submit your appeal as quickly as possible, especially if you need the service urgently. You can request expedited review simultaneously with your standard appeal if there is medical urgency.

Can my doctor help me with a prior authorization appeal?

Absolutely, and their involvement is critical. Your physician should provide a detailed letter of medical necessity, submit clinical records supporting the request, and be available to respond to plan requests for additional information. Physicians who are familiar with the peer-to-peer review option, speaking directly with the plan's medical reviewer, can also request that process.

What is a peer-to-peer review?

A peer-to-peer review is a direct conversation between your treating physician and the plan's medical director or physician reviewer. It is not a formal step in the appeals process but can often resolve a denial faster than a formal appeal. Ask your physician to request a peer-to-peer review immediately after a denial, before or alongside filing a formal appeal.

Does Original Medicare have prior authorization requirements?

Rarely. Original Medicare does not require prior authorization for most services. Physicians order covered services and Medicare pays. This is one of the most practically significant differences between Original Medicare and Medicare Advantage for people with complex or ongoing health needs.

Bryce Casson

Licensed Independent Medicare Broker

Bryce Casson is an independent Medicare insurance broker who works with every major carrier. He does not represent any single insurer, which means his recommendations are based on what actually fits each client's situation, not on commissions or quotas.