How to appeal a medical bill
A step-by-step guide to appealing a medical bill or an insurance denial — what to gather, what to say, and the deadlines you have to hit.
Skip ahead: if you already know why you're appealing, use the free Appeal Letter Builder to generate a draft in about a minute.
- 1
Request an itemized bill
The one-page summary hospitals send first almost never shows individual charges. Call billing and ask for a fully itemized statement with CPT and revenue codes. Federal law requires them to provide it. Roughly 8 in 10 itemized bills contain at least one error.
- 2
Check for billing errors
Compare every line to the care you actually received. Common errors: duplicate charges, services you never got, wrong CPT codes, room charges for days you were discharged, and 'facility fees' for a doctor visit. Circle anything that looks wrong.
- 3
Pull your Explanation of Benefits (EOB)
Log into your insurer's portal and download the EOB for this claim. The EOB shows what the insurer paid, what they denied, and — critically — the denial code and remark code. Those codes tell you exactly why you owe what you owe.
- 4
Identify the reason and your rights
Was the service denied as 'not medically necessary'? Was it out-of-network at an in-network hospital (protected by the No Surprises Act)? Was prior authorization missing? Was it a coding error? Your appeal argument depends on which of these applies.
- 5
Write and send your appeal letter
Send a written appeal to the insurer within the deadline printed on your EOB (usually 180 days). Include the claim number, the specific charges you're disputing, the reason it should be covered, and any supporting documents (doctor's letter, medical records). Send it certified mail or through the insurer's online portal so you have proof.
- 6
Escalate to an external review if denied
If the insurer denies your internal appeal, you have the right to a free external review by an independent third party. You typically have 4 months from the denial letter. External reviewers overturn insurer denials roughly 40–50% of the time.
Ready to draft your appeal?
Paste your denial letter or bill into the builder and it will produce a tailored draft citing the right statute and grounded in your facts.
Open the Appeal Letter BuilderEducational content — not legal or medical advice. Confirm deadlines and rights with your state insurance department or a nonprofit patient advocate.