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Your Claim Was Denied: The Appeal Playbook

SmartHealthMatch team · Reviewed by a licensed health insurance advisor · Updated July 2026

A denied claim feels final. It isn't. On ACA-compliant health plans, a denial is legally the opening of a process, not the end of one — you have a defined right to an internal appeal, and after that, to an independent external review whose decision your insurer must follow. A large share of denials are administrative — a coding mismatch, a skipped prior authorization — and get fixed with paperwork, not confrontation. This guide walks the whole path — decoding the denial, the deadlines on both sides, the documents that carry weight, how to frame the letter, and when your state insurance department should hear about it.

Step one: decode the denial before you do anything else

You'll usually learn about a denial from an explanation of benefits (EOB) or a formal denial letter. Somewhere on it is a reason — often a code plus a sentence. That reason determines your entire strategy, so pin it down precisely. The most common categories:

• Administrative or coding errors. A wrong procedure code, a mismatched diagnosis, a claim filed to the wrong plan. Often the provider's billing office can refile a corrected claim — no formal appeal needed.
• Missing prior authorization. The service required advance approval and nobody obtained it. Appeals here focus on why the service was needed and, where true, why authorization wasn't feasible.
• Out-of-network care. The provider wasn't in your plan's network. If no in-network option was reasonably available, or the care was emergency care, that's the core of your appeal. Our explainer on how networks actually work covers the background.
• "Not medically necessary." The plan's reviewer concluded the service didn't meet its clinical criteria. These are the denials where appeals — especially external review — matter most, because they turn on medical judgment.

Also pull out your plan documents: the Summary of Benefits and Coverage and the full Evidence of Coverage. Your appeal will quote them. If those documents are unfamiliar territory, start with our guide to reading a Summary of Benefits.

Layer one: the internal appeal

Every ACA-compliant plan must give you an internal appeals process, and it's free to use. The essentials as of 2026:

• Your deadline: generally 180 days from the denial notice to file. The letter itself must tell you the exact deadline and how to file — treat it as the authoritative source.
• Their deadline: generally 30 days to decide an appeal for care you haven't received yet, and 60 days for care you've already received.
• Urgent situations: if the standard timeline could seriously jeopardize your health, you can request an expedited appeal, typically decided within 72 hours.

Two rights people rarely use: you're entitled to a free copy of your entire claim file, and to the specific clinical criteria or internal rule the plan relied on. Request both in writing at the start — it's far easier to rebut a standard you can actually see.

Layer two: external review — the legally mandated second opinion

If the internal appeal upholds the denial, ACA-compliant plans must offer external review: your case goes to an independent review organization with no financial stake in the outcome. This right generally applies to denials involving medical judgment (including medical necessity and experimental-treatment determinations) and to rescissions of coverage. Key mechanics:

• You typically have up to four months after the final internal denial to request it, though some state-run programs set different windows — your final denial letter will state yours.
• Standard external reviews are generally decided within 45 days; expedited reviews for urgent care can be decided in as little as 72 hours, and in urgent cases you can often request internal and external review at the same time.
• The decision is binding on the insurer. If the independent reviewer sides with you, the plan must pay.

Depending on your state and plan type, external review runs through a state program or a federally administered process; either way the cost to you is minimal, and often nothing.

Timelines are the general federal standards as of 2026; your plan documents and state rules control, and your denial letters must spell out the deadlines that apply to you.

Build the file: documentation that carries weight

Strong appeals are assembled, not written. Gather:

• The denial letter and EOB, with the reason code.
• The plan language that supports coverage — quote the Evidence of Coverage by page and section.
• Relevant medical records: test results, imaging, treatment history, prior therapies tried.
• A letter of medical necessity from your treating physician — usually the single most persuasive document, especially against a medical-necessity denial.
• A call log: every phone contact with the plan, with date, representative name, and reference number.
• Proof of any prior authorization you did obtain, if the denial claims one was missing.

Framing the appeal letter

Keep it factual, organized, and anchored to the plan's own language. A structure that works:

• Open with the identifiers: "I am appealing the denial of claim [number] for [service] provided on [date], denied on [date] for the stated reason: [quote the reason exactly]."
• State the ask: "I request that this denial be reversed and the claim paid according to the terms of my plan."
• Rebut the stated reason directly: "The Evidence of Coverage, section [X], covers this service when [criteria]. The enclosed records from Dr. [name] document that these criteria are met, specifically [facts]." One reason, one rebuttal — don't argue points the plan never raised.
• List enclosures and close with a request for a written decision within the required timeframe.

Send it by a method that produces a receipt, keep copies of everything, and calendar the plan's decision deadline the day you mail it.

When to bring in your state insurance department

State insurance departments regulate fully insured plans — including every marketplace plan — and handle consumer complaints at no charge. Call yours when the insurer misses its own decision deadlines, won't provide the claim file or clinical criteria, or ignores procedural rules — or when you want help navigating external review, which many states administer directly. One boundary: self-funded employer plans (common at larger companies) are regulated federally instead, and the U.S. Department of Labor is the analogous resource. Your HR department can tell you which kind you had.

A note on plan type: these rights aren't universal

Everything above describes ACA-compliant coverage — marketplace plans and most employer plans. Private underwritten plans and other non-ACA coverage may handle appeals differently, under the contract and state law rather than the federal framework, and the external-review right may not apply the same way. It's part of a bigger trade-off worth understanding before you ever file a claim: private underwritten plans are not guaranteed issue, and they may limit or exclude pre-existing conditions. For anyone with meaningful health history — and for most households that qualify for subsidies — an ACA marketplace plan, with its guaranteed-issue rules and standardized appeal rights, often wins. Our explainer on what "underwritten" means lays out the distinction in full.

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