Upheld: What Happens When You Appeal, by Payer

Two findings sit in the public record, both true, pointing in opposite directions. In ACA marketplace plans, a consumer who appeals a denied claim usually loses: insurers upheld 66% of internal appeals in 2024.¹ In Medicare Advantage prior authorization, an appeal usually wins: 80.7% of appealed denials were partially or fully overturned that same year.³ The word “appeal” is doing very different work in those two sentences, and the difference is the story.

The marketplace numbers come from federal transparency data on HealthCare.gov plans, compiled by KFF. In 2024, insurers denied roughly 85 million in-network claims. Consumers appealed at least 262,982 of them — under 1% — and insurers upheld 165,863 of those appeals, or 66%.¹ The year before, consumers filed 376,508 internal appeals and insurers upheld 56%.² Appeal volume fell by roughly a third while the uphold rate rose ten points; the issuer mix reporting each year changes, so we read these as two annual snapshots rather than a trend.

Past the internal appeal, the funnel narrows to almost nothing. Marketplace enrollees took at least 5,881 upheld denials to external review in 2024 — 4% of the appeals that failed internally.¹ And what happened to those? The federal data cannot say:

That is the state of the art in appeal transparency: the last, independent stage of the process — the one where the insurer no longer grades its own work — produces numbers too small to publish.

The other side of the ledger comes from Medicare Advantage. In 2024, MA insurers made 52.8 million prior authorization determinations and denied 7.7% of requests in full or in part. Only 11.5% of those denials were appealed — and 80.7% of the appeals succeeded.³ The pattern is stable: KFF's analysis of CMS data found more than eight in ten appeals overturning the initial denial in every year from 2019 through 2024.³ The AMA put the question directly in a 2024 headline — “Over 80% of prior auth appeals succeed. Why aren't there more?” — reporting the same KFF analysis, which found 83.2% of appealed MA prior-auth denials overturned in 2022.⁴ Note the population carefully: this is Medicare Advantage prior authorization, largely provider-driven, not commercial claims appealed by consumers.

Where investigators have looked closest, the rate runs higher still. HHS's Office of Inspector General examined skilled-nursing-facility admissions across the 19 largest MA insurers and found that when denials were appealed, 95% were overturned in favor of the enrollee — a rate the OIG itself flagged as raising “concerns about initial denials.”⁵ And on the claims side, Premier's survey of hospitals and health systems found 54.3% of denied claims ultimately overturned — after what providers described as multiple rounds of costly appeals.⁶

These numbers do not contradict each other, because they do not measure the same thing. The marketplace 66% covers consumers appealing denied in-network claims, once, inside the insurer's own process. The MA 80.7% covers prior-authorization appeals, typically filed by clinicians with the chart in hand, in a program where coverage rules are federally anchored. Premier's 54.3% measures institutional persistence — hospitals working the same claim through round after round. Different populations, different denial types, different appeal levels, and selection effects on every side: the 11.5% of MA denials that get appealed are plausibly the strongest cases, and the marketplace's 36%-denied-for-“other” haystack¹ surely includes appeals that were never winnable.

What the records do agree on is the shape of the funnel. Where appeals are rare and stop at one round, the insurer's decision usually stands. Where the appellant is equipped and persistent — a clinician, a hospital, a case built on documentation — the denial usually falls. The uphold rate is not a fixed property of the denial. It is, in large part, a property of who is still standing at each stage.

This piece set out to report uphold rates issuer by issuer. The honest finding is that no such table has been published. KFF reports marketplace denial rates by parent company, but its appeals analysis is aggregate only; the underlying federal public-use files suppress small cells, and the OIG names no insurer-level overturn rates in its skilled-nursing report.¹⁵ Rather than reconstruct rates the agencies themselves declined to publish, we report the aggregates and the gap. When issuer-level appeal outcomes appear in a citable public source, this page will carry them.