Most appealed denials get overturned. Most denials are never appealed.

Every billing team has a pile nobody talks about. It is the stack of denials no one had time to appeal: the small balances, the ones with confusing reason codes, the ones for patients who have already moved on. The public numbers suggest that pile is worth more than most practices think.

What the data shows

KFF analyzed the prior authorization data Medicare Advantage insurers report to CMS and published the results in January 2026. In 2024, insurers made nearly 53 million prior authorization determinations. About 4.1 million, or 7.7%, were fully or partly denied, up from 6.4% in 2023. Only 11.5% of those denials were appealed. Of the ones that were, 80.7% were overturned in full or in part, and KFF found more than eight in ten appeals succeeded in every year it examined.

Those are prior authorization decisions, not claim denials, but the pattern is familiar from claims work. Physicians also expect denials to keep rising. In the AMA's prior authorization survey, 61% of physicians said they were concerned that payers' use of AI is increasing denials.

Why so few denials get appealed

It is rarely a decision. Appeals fall through the cracks because nobody owns them. The denial arrives on a remittance with a reason code, gets posted, and waits in a work queue behind new claims. By the time someone opens it, the appeal deadline is close or already gone.

The second reason is that many denials look final when they are not. A medical necessity denial reads like a verdict. Often it means the plan did not see the documentation, and a short letter with the right chart note attached is enough to change the answer.

A workable appeals routine

1. Sort denials by reason code every week, not only by age. Twenty denials with one cause are one fix.
2. Log the plan's appeal deadline next to each denial on the day it is posted.
3. Appeal with the documentation the denial reason points to, and cite the plan's own policy where you can.
4. Track outcomes by payer and reason. If a plan overturns most of its own denials on appeal, raise the pattern with your payer representative.
5. Fix the upstream cause, so the same denial does not come back next month.