The 2026 Insurance Denial Report

Overturn rate by denial type

Share of appealed denials overturned in the patient's favor. n = sample size per category.

Source: Apellica external-review outcomes dataset (n=73,987), 2026.

The appeal gap

Denials are common and appeals are rare. KFF found that HealthCare.gov insurers denied roughly 19% of in-network claims, yet consumers appealed fewer than 1% of those denials. Independent KFF data on appealed denials shows roughly 44% overturned, closely matching Apellica's 46.9% across a much larger external-review sample. Two independent datasets reach the same conclusion: appealing works far more often than people expect, and almost no one does it.

That gap is the story. Carriers can deny in volume because they know the overwhelming majority of denials are simply abandoned. A denial letter is a first answer, not the final word. When a denial reaches an independent external reviewer, close to half are reversed.

What a winning appeal contains

Across the overturned cases, the appeals that succeed share a structure. They quote the carrier's own denial reason, then demand and rebut the specific clinical criteria the plan applied. They map the patient's medical record to each criterion, one by one, rather than arguing in general terms. They cite the controlling federal rule, 29 C.F.R. 2560.503-1 for employer plans or 45 C.F.R. 147.136 for ACA plans, to lock the timeline and force criteria disclosure. And they make a specific demand for reversal rather than a request to reconsider.

Generic letters that simply ask a plan to take another look do not move reviewers. Point-by-point rebuttals tied to the plan's own policy and the medical record do. The pattern holds across denial types: the appeal that wins is the one that turns the carrier's criteria into a checklist the reviewer must concede.

Methodology

The figures above come from Apellica's analysis of 73,987 independent external-review (IRO) decision outcomes for US health-insurance denials. An outcome is counted as overturned when the independent reviewer reversed or modified the plan's denial in the patient's favor, in whole or in part. Outcomes are segmented by the primary denial reason recorded for each case: medical necessity, experimental or investigational, formulary or pharmacy, and urgent or expedited review.

External-review outcomes are a conservative measure of how often denials are wrong, because they reflect only the small share of denials that are appealed all the way to independent review. Many denials are also reversed earlier, at the internal-appeal stage, and are not counted here. Category overturn rates are reported with their sample sizes so readers can weigh each estimate. The dataset reflects appealed denials and is not a random sample of all denials. It is the population of cases that reached external review.

Sources

1. Apellica external-review outcomes dataset (n=73,987), 2026
2. KFF, Claims Denials and Appeals in ACA Marketplace Plans
3. 29 C.F.R. 2560.503-1, ERISA claims procedure (employer plans)
4. 45 C.F.R. 147.136, internal claims and appeals and external review (ACA plans)