Global denial rates, appeal success rates by procedure and country, and the data behind 200+ million denied claims annually. Citable source for journalists, lawyers, and researchers.
Four numbers that define the insurance denial crisis.
US marketplace health insurers denied an average of 18% of in-network claims in 2023, with some insurers exceeding 30% denial rates for specific plan types (KFF analysis of CMS Transparency in Coverage data).
Medicare Advantage plans denied 1 in 7 prior authorization requests in 2023, with CMS finding that many denials would have been approved under traditional Medicare — suggesting systematic over-denial (CMS OIG Report 2023).
Of the 200+ million insurance claims denied annually in the US, fewer than 0.2% are formally appealed — despite 63% of appeals succeeding. This represents an estimated $155+ billion in legitimate claims that go unchallenged each year.
The appeal success rate varies significantly by procedure: ER visits have the highest overturn rate (72%) while fertility treatments have the lowest (48%). Documentation quality is the single largest predictor of appeal success across all categories.
In the UK, the Financial Ombudsman Service upheld consumer complaints in approximately 35% of insurance cases in 2023/24, with the FOS handling over 75,000 insurance complaints annually.
Independent External Review — a legally mandated process under the ACA — overturns insurer denials approximately 72% of the time, yet fewer than 1 in 1,000 eligible patients exercise this right.
Compiled from CMS Transparency in Coverage data and KFF analysis. Data represents US commercial health insurance plans.
Source: CMS Transparency in Coverage data, KFF analysis, AHIP utilization reports. Figures are approximate averages across US commercial plans.
Survey data on the primary barriers to filing insurance appeals. Understanding these barriers reveals a systemic patient rights failure.
The ClaimBack Insurance Denial Report 2026 was compiled from the following primary sources:
Where precise figures are unavailable, approximate ranges based on available data are stated and labelled accordingly. All figures are subject to revision as primary sources update.
Published: March 2026. Next update: September 2026.
This report is available under Creative Commons Attribution 4.0 license. Please attribute ClaimBack Research Team when citing figures from this report.
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