Health Insurance Claim Denied? How to Appeal
A denial is a first answer, not the final one. Federal law gives you two formal rounds — an internal appeal to the health plan, then an external review by an independent organization the plan must obey. Many denials are overturned, especially when the problem was paperwork, coding, or documentation the plan never saw. Here is the process, with the deadlines that decide whether you still have a case.
Step 0: Read the denial before doing anything else
Your denial letter (and the EOB) must state why the claim was denied and how to appeal. The reason chooses your strategy:
- Coding or billing error (wrong code, missing modifier, mismatched diagnosis) → this is the provider’s mistake. Ask the billing office to correct and resubmit before you spend your appeal on it.
- Missing information / prior authorization → the fix is documentation; your provider’s office usually supplies it.
- “Not medically necessary” / experimental → a true appeal: you will need your doctor’s letter and records showing why the care fit your condition.
- Out of network / not a covered benefit → check the No Surprises Act first (emergency care and out-of-network clinicians at in-network facilities are protected), then appeal with the plan language that supports coverage.
Step 1: File an internal appeal — within 180 days
- Deadline: you must file within 180 days (6 months) of receiving the denial notice for most plans. The denial letter states your exact deadline — trust it over any general guide.
- How: complete the plan’s appeal form, or write a letter with your name, claim number, and health plan ID number, stating clearly that you are appealing the denial (CMS).
- Include: a letter from your doctor explaining medical necessity and addressing the plan’s stated reason, relevant medical records and test results, and any plan pages that support coverage. A sample letter is Template 3 in the dispute letter library.
- Urgent situations: if waiting would jeopardize your health, you can request an expedited appeal, including by phone.
- Send with proof: certified mail or the plan’s portal with confirmation saved. Keep copies of everything — your external review, if needed, is built from this file.
The plan must decide pre-service appeals quickly (generally 30 days) and post-service claims within about 60 days; your denial letter and plan documents give the exact timelines.
Step 2: If the plan says no again — external review
After the internal appeal is denied, you have the right to an independent external review:
- Deadline: file within 4 months of the internal-appeal denial.
- Who decides: an Independent Review Organization (IRO) with no ties to your plan. Your plan must give you the external review form, the plan pays for the review, and the plan must comply with the IRO’s decision.
- Speed: decisions are fast for urgent cases (days for emergency treatment) and within about 20–45 days for standard cases, depending on your state process.
- Cost to you: nothing.
Step 3: If both rounds fail
- Ask the provider to reduce the bill now that insurance is settled — self-pay and prompt-pay discounts are commonly 20–40% when asked for explicitly.
- Apply for the provider’s financial assistance if the balance is unaffordable.
- Complain to your state department of insurance if you believe the plan mishandled the appeal itself (missed deadlines, ignored evidence).
Appeal file checklist
All deadlines in one view: Medical bill dispute deadlines.
Frequently asked questions
How long do I have to file an internal appeal?
Within 180 days (6 months) of receiving notice that your claim was denied, for most plans (CMS; state insurance guidance). Your denial letter controls — check it first, because the clock runs from the notice date, not from when you open the envelope.
What is an external review, and who pays for it?
An external review is a fresh decision by an Independent Review Organization that is not affiliated with your health plan. The plan must provide the review form, the plan pays for the review, and the plan must follow the IRO’s decision.
What should my appeal letter include?
Your name, claim number, and health plan ID number; a clear statement that you are appealing the denial; the reason you believe the claim should be paid; and supporting evidence — above all, a letter from your doctor and the medical records behind it (NAIC guidance).
Should I resubmit the claim instead of appealing?
If the denial came from a fixable error — a wrong code, a missing document, a claim sent to the wrong plan — ask the provider to correct and resubmit first; it is faster than an appeal. Appeal when the plan made a judgment call (medical necessity, coverage, authorization) that you are asking it to reverse.
Sources: CMS health insurance appeals fact sheet; NAIC, “How to Appeal a Denied Claim”; Texas Office of Public Insurance Counsel appeal steps; National Association of Insurance Commissioners consumer guidance. Educational information, not legal advice. Reviewed 2026-10-22.