How to Appeal a Health Insurance Denial (and Actually Win)

The Affordable Care Act (Section 2719) requires most health plans to give you two layers of appeal. First, an internal appeal: the insurer must re-review its own decision, with your evidence in the file. Second, if the internal appeal fails, an external review: an Independent Review Organization — clinicians with no stake in the outcome — re-decides denials that involve medical judgment, and their decision is binding on the insurer.

Employer self-funded plans follow parallel rules under ERISA (29 CFR 2560.503-1), which require a 'full and fair review' and entitle you — free, on request — to the documents, criteria, and reviewer credentials behind the denial. Ask for them. Knowing exactly which guideline was applied lets your appeal target it directly.

Step 1 — Decode the denial. The letter must state the specific reason (medical necessity, prior authorization, out-of-network, experimental, coding error, not covered) and the plan provision behind it. The reason determines your strategy.

Step 2 — Build the record. Request your claim file from the insurer and your records from the provider. For clinical denials, ask your physician for a letter of medical necessity that answers the insurer's criteria point by point.

Step 3 — Write a citation-backed appeal letter. Business format, claim identifiers up top, 3–5 arguments each tied to plan language or law, a specific remedy, and a response deadline. (More on the letter below.)

Step 4 — Escalate. If the internal appeal fails, request external review. If your health can't wait, request expedited handling at every stage — decisions can be required in as little as 72 hours.

Miss a deadline and you can lose the right entirely. Calendar these the day the denial arrives — and always go by the dates printed in your own denial letter, which control:

Reviewers read stacks of appeals. The ones that win make the reviewer's job easy: identifiers, the decision being appealed, then arguments in the shape 'here is the fact, here is the rule, here is why the rule applied to the fact defeats the denial.'

Cite specifics — your plan provision by section, ACA Section 2719 for your appeal rights, ERISA for employer plans, and the clinical guidelines your physician relies on. Close with the remedy you want (approve the claim, authorize the care), a response deadline, and notice that external review comes next. Professional and assertive; never pleading. The subtext that moves insurers isn't anger — it's a file that looks one step from a regulator.

'Not medically necessary' is the most common denial reason and the most beatable. It doesn't mean your doctor was wrong — it means a reviewer, often applying commercial screening criteria like MCG or InterQual, concluded the treatment didn't fit the insurer's internal guidelines. That's a judgment call, and judgment calls are what appeals exist to challenge.

The winning move: get the exact criteria the reviewer applied (you're entitled to them), then have your treating physician write a letter that maps your diagnosis, treatment history, and the clinical evidence onto those criteria line by line. Either your facts satisfy the criteria — shown explicitly — or the criteria are narrower than your plan's own definition of medical necessity, which is itself a winning argument. At external review, independent clinicians weigh current medical evidence, not the insurer's policy file.

AppealIQ turns your denial into a formal, citation-backed appeal letter. Paste or photograph your denial letter (it's read on your device — only the text is sent), answer a short intake about your claim, and get a letter that cites ACA Section 2719, ERISA rules, and medical-necessity standards — built from your facts, never invented ones. Start with the free Denial Analyzer to see your appeal angle first; the full letter is $19 one-time or unlimited on a plan.