Do appeals work?
Denied a claim right now? Use the appeal letter generator to build a formatted appeal in your browser.
Look up any insurer on the insurer rankings to see its own appeal record.
Prior authorization is the other wall
Before certain care (post-acute care, MRIs, specialty drugs) your plan must approve it in advance. KFF's 2026 analysis of insurers covering ~71 million people found plans denied 12-18% of standard prior-authorization requests in 2025. In Medicare Advantage, UnitedHealthcare denied the most standard requests (17%); in ACA marketplace plans, Centene denied the most (25%). Medicare Advantage data on this comes from insurer websites, not a CMS public file: CMS only began requiring standardized public reporting recently, which is why this site cannot yet compute prior-auth rates the way it computes denial rates.
Frequently asked
Do insurance appeals actually work?
Yes, far more than people expect. Fewer than 0.2% of denied claims are appealed, but about one in three internal appeals succeeds, and independent external reviewers overturn plan decisions at even higher rates.
How long do I have to appeal a denied claim?
Internal appeals are typically due 180 days from the denial letter for marketplace plans. Deadlines differ by plan, so check your denial letter and file early.
What is external review?
If the internal appeal fails, an independent reviewer not employed by your insurer re-examines the denial. For marketplace plans the reviewer's decision binds the insurer.
What should an appeal letter include?
Your claim number, the denial reason stated in the letter, your membership details, and evidence: doctor's notes, medical records, and a copy of the plan's own coverage rules. The appeal letter generator on this site builds a formatted letter from those pieces.
Where does the appeal data on this page come from?
CMS Transparency in Coverage filings, which include each insurer's reported internal appeal and external review counts alongside its denial counts.