Insurers deny about 14% of all claims — but fewer than 1% of people appeal. Here are the 8 most common denial reasons and exactly how to fight each one.
ClaimBack uses AI and data from thousands of real denials to generate a customized appeal letter — tailored to your insurer, denial reason, and state.
Start My Appeal — Free →"Not medically necessary" is the #1 denial reason, accounting for about 32% of all claim denials. This means your insurer's medical reviewers disagree with your doctor's recommendation — but the good news is that 59% of these denials are overturned on appeal when supported by proper documentation.
On average, about 55% of properly filed appeals are successful. However, fewer than 1% of people who receive a denial actually file an appeal. Documentation quality and appeal strategy significantly impact success rates.
Most health insurers give you 180 days (6 months) to file an internal appeal. Some plans allow only 60-90 days. Check your denial letter for the exact deadline. After exhausting internal appeals, you typically have 4 months to request an external review.
Yes. Most plans offer two levels of internal appeal. After that, you can request an independent external review, file a complaint with your state insurance department, or in some cases, pursue legal action.
Insurance denied your claim as not medically necessary? Learn the exact legal standard, how insurers make this determination, counter-arguments, sample appeal language, and success rates.
Read guide →Insurance denied your claim for an out-of-network provider? Learn the No Surprises Act protections, network adequacy rules, and step-by-step appeal strategy to get your denial overturned.
Read guide →Insurance denied your claim for missing prior authorization? Learn when this denial is legally challengeable, how to request retroactive authorization, and the step-by-step appeal strategy.
Read guide →Insurance says your treatment isn't a covered benefit? Learn how to challenge this denial, check your plan's actual coverage, and appeal successfully.
Read guide →Insurance denied your treatment as experimental or investigational? Learn the appeal strategies, legal protections, and sample language to fight this denial.
Read guide →Insurance denied your claim for a pre-existing condition? Learn when this denial is illegal under the ACA, when it may be lawful, and exactly how to appeal with the right legal arguments.
Read guide →Insurance denied your claim for late filing? Learn the filing deadlines, which exceptions apply, and how to successfully appeal a timely filing denial with documentation and legal arguments.
Read guide →Insurance denied your claim as a duplicate? Learn why duplicate denials happen, how to prove your claims are legitimate, and how to appeal this common billing error.
Read guide →Step-by-step guide to writing a professional, persuasive insurance appeal letter that gets results.
Read guide →These 10 evidence-based strategies have helped policyholders overturn insurance denials. Learn what actually works — from documentation to regulatory leverage.
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