How do I write an appeal letter for a denied health insurance claim?

Use the free tool — Health Plan Denial Appeal

Why write an appeal letter

About half of appealed denials get overturned — and almost nobody appeals. The denial letter usually hides the real reason in a reason code and hides the deadline in fine print. A clear appeal letter puts the medical facts in front of the reviewer, in plain words.

What the letter needs

An appeal letter built around what the plan actually has to consider should include:

The date, reason code, and service from your denial letter
Your plan type — employer, ACA marketplace, or individual
What your doctor says about medical necessity
The clinical criteria and guideline the plan used, if you know it
The doctor's rationale for the treatment or service
The prior-authorization facts, if that's the issue
A request for the reviewer's credentials and the guideline they used

The real reason behind a denial is usually one of these: medical necessity, prior authorization, out-of-network, coding, or "experimental." Knowing which one you're dealing with shapes what the letter should say.

Know your deadlines

Under the ACA and Florida law, you generally have:

180 days to file an internal appeal with the plan
4 months to request an external review after the internal appeal

Both deadlines are computed from the date printed on your denial letter, not from the date you received it or noticed it. Confirm the exact dates on your own letter and with your plan — this material doesn't cover every possible exception.

What to request from the plan

The plan must give you certain documents free of charge so you can appeal. Ask for:

The specific clinical criteria or guideline used to deny the claim
The reviewer's credentials
Any internal policy documents connected to the denial

What this is not

This is not legal or medical advice. It explains ACA, ERISA, and Florida appeal rules for employer and marketplace plans — it does not file appeals for you. It does not cover Medicare, Medicare Advantage, or Medicaid fee-for-service; those programs have their own appeal systems, so use Medicare Decoder instead if that applies to you.

For free help, contact the Florida Division of Consumer Services at 1-877-693-5236, or, for employer plans, the U.S. DOL EBSA at 1-866-444-3272.

What to do next

Paste your denial letter or explanation of benefits into the free tool. It reads your own document — the date, the reason code, the service, your plan type, and what your doctor says — and gives you the real reason in plain words, your internal and external appeal deadlines already computed from your letter's date, the documents to request from the plan, and a draft appeal letter your doctor can sign. Always confirm the details with your plan or a professional before you rely on them.

Use the free tool

Health Plan Denial Appeal is an informational tool for commercial (employer, ACA marketplace, individual) health plan denials, based on the ACA (45 CFR 147.136), ERISA claims rules (29 CFR 2560.503-1) and Florida Statutes 627.6472 / 627.602 as of 2025–26. It does not cover Medicare, Medicare Advantage or Medicaid fee-for-service, which have their own appeal systems. It is not legal or medical advice and does not file appeals. It is not affiliated with any insurer, employer or agency.