Millions of Medicare Advantage enrollees who ask an insurer to reconsider a denied prior-authorization request end up winning. Insurers made 52.8 million prior-authorization determinations in 2024, denying 4.1 million requests in full or in part, according to Centers for Medicare and Medicaid Services data analyzed by KFF. Just 11.5% of those denials were ever appealed to the insurer, but when a member did appeal, 80.7% of the initial denials were partially or fully overturned. The gap between how rarely people contest a denial and how often the contest succeeds is now drawing attention from Congress and from the agency that regulates Medicare Advantage.
The Five-Level Appeal Most Members Never Use
A Medicare Advantage denial is formally called an adverse organization determination, and it comes with the right to five successive levels of appeal. The first, a health plan reconsideration, must be filed within 65 days of the denial notice by the member, a representative, or the treating provider, following the instructions the plan is required to send with its decision. If the plan upholds its own denial at that first level, federal rules require it to automatically forward the case to an outside reviewer rather than letting the matter end with the insurer that made the original call.
That outside reviewer is an Independent Review Entity working under contract with CMS, and it runs on the same clock the plan does: 30 days for a standard pre-service request, 60 days for a payment dispute, and just 72 hours if a doctor certifies that waiting could seriously jeopardize the patient’s health. A member who clears both of those stages and is still denied can escalate to an Administrative Law Judge, but only if the disputed care meets a minimum dollar threshold, set at $200 for 2026, and can continue on to a Medicare Appeals Council review and, ultimately, federal district court, where the case must be worth at least $1,960 in 2026 to qualify.
Reaching those later levels requires paperwork most members never file: a formal hearing request submitted to the Office of Medicare Hearings and Appeals, either on a federal form or in writing with the case’s appeal number, dates of service, and supporting medical records attached, and, if that hearing also fails, a separate written request to the Medicare Appeals Council within 60 days. Few denials travel that far. The reversals CMS tracks overwhelmingly happen at the first or second level, before a case ever reaches an administrative judge.
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Why Most Denials Never Get Contested
CMS data reviewed by KFF and published January 28, 2026, shows the appeal rate has climbed only modestly even as denials have grown more common. In 2019, 7.5% of Medicare Advantage prior-authorization denials were appealed; by 2024 that figure had risen to 11.5%, close to the 11.7% recorded in 2023. Denials themselves ticked up to 7.7% of all prior-authorization requests in 2024, from 6.4% in 2023, as the number of requests submitted on behalf of Medicare Advantage enrollees grew to nearly 53 million.
The reversal rate is not uniform across insurers. Kaiser Foundation Health Plan overturned the smallest share of its own denials on appeal in 2024, 51.0%, while Centene Corporation overturned 95.5%. Centene also carried one of the higher initial denial rates among large insurers, 12.3% of requests, meaning a member enrolled there faced worse odds going in but far better odds once the file reached reconsideration.
Traditional Medicare, which uses prior authorization far more sparingly, shows a strikingly different pattern for the one year CMS tracked appeal outcomes by service category, 2022. Only 6.4% of denied traditional Medicare prior-authorization requests were appealed, but the share that succeeded varied widely by category: 63.9% for durable medical equipment and prosthetics, compared with 26.3% for non-emergency ambulance transport and 22.2% for certain hospital outpatient procedures. The contrast suggests Medicare Advantage’s uniformly high, 80%-plus reversal rate across every insurer is not simply a feature of how prior authorization works in general.
KFF’s analysis offers two explanations that are not mutually exclusive: the original denial may have been wrong, or the initial request lacked documentation that a provider later supplied on appeal. Either way, the practical effect on the patient is the same. Care that a doctor ordered, and that was ultimately approved, was delayed by the added step of contesting the plan’s first answer, a delay the researchers note can carry real health consequences for the roughly one in nine denied members who pursue it.
The Pressure Building on Insurers
The overturn data have become ammunition in Congress. Bipartisan bills introduced in the House and Senate would codify recent federal rules narrowing how Medicare Advantage plans set prior-authorization criteria, and a separate House bill would specifically penalize insurers when their initially denied requests are overturned on appeal too often. Beginning in 2026, a federal rule requires Medicare Advantage insurers to publicly post how many prior-authorization requests they approved, denied, and later approved after appeal, giving future enrollees a way to compare an insurer’s reversal rate before choosing a plan during open enrollment.
None of the penalty proposals has been enacted, and CMS has not moved to require insurers to justify a denial before it is issued rather than after a member appeals it. For now, the burden of correcting a wrong prior-authorization decision still falls on the person the decision was made about, and the reversal data indicate that when that person is willing to navigate the plan’s own five-level process, the odds run substantially in their favor.
This article was researched and drafted with the assistance of artificial intelligence.
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