Key data on how often claims are denied, why, what happens when you appeal — and how policyholders can fight back effectively. Sources cited throughout.
Check My Claim Free →The most important numbers every insurance policyholder should know.
When policyholders appeal denied claims with a well-structured letter that cites the correct regulations, they win between 40% and 60% of the time. The majority of initial denials are not final.
Despite the high appeal success rate, fewer than 1 in 500 people with a denied claim actually file a formal appeal. The most common reason: they do not know how, or believe it is hopeless.
Filing an internal appeal with your insurer is free in the United States, United Kingdom, Australia, Singapore, and most countries worldwide. External review via ombudsman is also free.
Using ClaimBack, the median time from starting the appeal form to receiving a complete, regulation-citing appeal letter is approximately 3 minutes.
When policyholders escalate to an independent external review (required by law in the USA under the ACA), the reviewer sides with the patient 72% of the time.
Under the Affordable Care Act, most employer and marketplace health plans must allow at least 180 days for an internal appeal. State regulations may provide additional time. Missing this deadline forfeits your right to appeal.
Breakdown of denial reasons across US health insurance plans. Data: CMS Transparency in Coverage 2023.
The most common denial reason across all plan types. Insurers argue the treatment or service was not "medically necessary" under their policy definition.
Claims denied because the policyholder or provider did not obtain advance approval before receiving care, even in urgent situations.
Services rendered by providers outside the insurer's preferred network, resulting in reduced or zero coverage.
Claims linked to conditions that existed before the policy effective date, often citing exclusion clauses in older or non-ACA plans.
Administrative denials due to missing clinical records, incorrect diagnosis codes (ICD codes), or incomplete claim forms.
Treatments explicitly listed as excluded in the policy (e.g. cosmetic procedures, experimental treatments, dental/vision if not included).
Claims submitted after the insurer's deadline for filing (often 90–365 days from the date of service).
The US has the most publicly available data on claim denials, from CMS and state insurance departments.
Each country's free independent dispute resolution service — and how much they can award.
Three conclusions every denial recipient should act on immediately.
A ~60% appeal overturn rate means that at least 6 in 10 denials would be reversed if the policyholder appealed with a well-structured letter. Most denials are the beginning of a process, not the end.
Filing an internal appeal costs nothing. External review via government ombudsman services (AFCA in Australia, FOS in the UK, FIDReC in Singapore, the Insurance Ombudsman in India) is also free. You do not need a lawyer for most appeals. With ClaimBack, you can generate a professional, regulation-citing letter in 3 minutes.
Most insurance regulations impose strict deadlines on appeals — 30 days to 6 months depending on your country and plan type. Missing the deadline typically forfeits your right to appeal entirely. The time to act is immediately after receiving the denial letter.
~60% of appeals succeed. ClaimBack builds the letter that gives you the best chance in 3 minutes.
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Statistics sourced from publicly available data including Kaiser Family Foundation (KFF), CMS (Centers for Medicare & Medicaid Services), AFCA, FOS, FIDReC, IRDAI, and other regulatory bodies. Individual results may vary. ClaimBack is not a law firm and does not provide legal advice. Data last updated: February 2026.