How to Appeal a Denied Health Insurance Claim
Insurers denied about 19% of in-network claims in 2024, roughly 85 million denials, and fewer than 1% were ever appealed, according to KFF’s 2024 claims denials analysis. A denied claim is a bill you may be expected to pay, and most people never fight it. This guide walks through the appeal process step by step: the deadlines that matter, the evidence to gather, and the free help available. Your appeal rights start with the plan you pick, so see our guide to choosing a health insurance plan during open enrollment to set yourself up before a denial ever happens.
How This Guide Was Built
This guide is built from primary sources: KFF’s 2024 claims analysis, Healthcare.gov’s appeal pages, CMS fact sheets, and DOL publications for employer plans. All facts were verified on 2026-08-07, and no appeal was filed by the author. Since July 1, 2026, the federal external review program is unavailable in AL, FL, GA, TX, WI, and U.S. territories except Puerto Rico.
How do you appeal a denied health insurance claim?
You appeal a denied health insurance claim by reading your denial letter, filing a written internal appeal within 180 days, and, if denied again, requesting an external review within four months. Healthcare.gov’s internal appeals page confirms those deadlines, and both steps are free under federal rules, so the calendar, not cost, is your main constraint.
Step 1: Read the denial letter and the EOB
Your denial letter is the roadmap: federal rules require it to state the specific reason for the denial and your appeal rights, per CMS’s index of health plan appeal requirements. Your Explanation of Benefits (EOB) shows the billed amount, the insurer’s allowed amount, and what you owe. Cross-reference the denial reason with your plan’s Summary of Benefits and Coverage. Before filing a formal appeal, check whether the denial is administrative: KFF’s analysis found administrative denials made up 25% of 2024 denials, and many are fixable with a corrected resubmission, such as a missing referral or a coding error, instead of a formal appeal.
Step 2: Gather your evidence
Effective appeals are built on documentation. Collect the claim receipt, the denial letter, and the EOB, then build an evidence packet that directly counters the stated denial reason. The strongest evidence includes a letter from your doctor explaining why the service was needed, treatment guidelines that support it, and records of any prior approvals. If the denial was for lack of prior authorization, show that the authorization was requested or granted.
Step 3: File the internal appeal within 180 days
You have at least 180 days from the initial denial notice to file, and the process is free, per the DOL’s guide to filing a claim for health benefits. File in writing via certified mail or the insurer’s secure portal so you have proof of submission. Healthcare.gov says the insurer must decide a standard internal appeal within 30 days if you have not received the service yet, or 60 days if you already have; urgent appeals get a decision within 4 business days, with written notice within 48 hours. The odds are better than you think: insurers upheld 66% of internal appeals in 2024, meaning roughly 1 in 3 denied claims was overturned at this stage, per KFF’s analysis. Yet only about 262,982 internal appeals were filed against roughly 85 million denied in-network claims, so most people never try.
Step 4: If denied again, request external review within 4 months
If the internal appeal is denied, you have four months to request an external review by an independent third party, and the decision is binding on the insurer, per Healthcare.gov’s external review page. The review costs $0 under the federal process, though some state independent review organizations may charge up to $25. One catch: as of July 1, 2026, the federal external review process is temporarily unavailable in Alabama, Florida, Georgia, Texas, Wisconsin, and U.S. territories except Puerto Rico, so readers there should follow their denial notice for where to request external review. Most people never get this far: KFF’s analysis found only 40% of insured adults believe they have a right to external appeal, yet it is one of the strongest tools available.
Step 5: Escalate: state insurance department, Consumer Assistance Program, or legal review
If external review is denied or unavailable, file a complaint with your state’s insurance department, which has regulatory authority over plans sold in your state. Federal Consumer Assistance Programs (CAPs) help you file appeals and complaints at no cost. For employer plans governed by ERISA, the DOL confirms you may have a right to sue in federal court once administrative appeals are exhausted. State resources can guide you too, like Washington state’s insurance commissioner and California’s independent medical review program.
Internal appeal vs. external review: what’s the difference?
An internal appeal is a review by your insurer, while an external review is an independent third-party decision that binds the insurer. You must exhaust the internal appeal first; external review is a separate, later step. Healthcare.gov explains both, and KFF data shows few denials ever reach either stage.
| Feature | Internal Appeal | External Review |
|---|---|---|
| Who decides | The insurance company | An independent review organization (IRO) |
| Filing deadline | At least 180 days from the denial notice (Healthcare.gov) | Four months from the internal appeal denial (Healthcare.gov) |
| Decision timeline | 30 days if you have not received the service yet; 60 days if you have; urgent: 4 business days (Healthcare.gov) | 45 days; urgent: 72 hours (Healthcare.gov) |
| Cost to you | $0 (DOL) | $0 federal; up to $25 in some states (Healthcare.gov) |
| Binding? | No | Yes, the insurer must follow the decision (CMS) |
When the No Surprises Act applies instead
The No Surprises Act applies when you get a surprise bill from an out-of-network provider at an in-network facility or in an emergency, not when a claim is denied. It holds you harmless from the bill and sends the dispute to Independent Dispute Resolution between your insurer and the provider, per the DOL’s guidance. Consumer appeals don’t apply here — if you get a surprise bill, call the No Surprises Help Desk at 1-800-985-3059.
Common appeal mistakes that cost you money
Most appeal failures are avoidable and follow a pattern: missed deadlines, unfocused arguments, and no paper trail. The stakes are real: insurers upheld 66% of internal appeals in 2024, but roughly 1 in 3 denials was overturned, so a well-built appeal can win, per KFF’s analysis. Avoid these five mistakes.
- Missing the deadline: 180 days for the internal appeal, four months for external review. Mark both dates the day you receive each notice.
- Not reading the denial reason: an appeal that doesn’t refute the stated reason, like “service excluded from benefits,” will fail.
- Filing only verbally: always create a written record. Use certified mail or the insurer’s portal so you have proof of submission.
- Ignoring the EOB: it shows what you owe and why, and any discrepancy between the denial letter and the EOB must be clarified.
- Skipping external review: roughly 1 in 3 denials is overturned at internal appeal, and a 2025 Health Affairs study found almost half of external review decisions overturned the initial denial in four states with public data. Most patients never file, which leaves money on the table.
FAQ
How long do I have to appeal a denied health insurance claim?
You have at least 180 days from the denial notice to file an internal appeal, and four months from an internal appeal denial to request external review, per Healthcare.gov. These are federal minimums; your plan can allow more time. Your denial letter should state your exact deadlines, so check it first.
Can I appeal a denial if I have an employer health plan?
Yes. Most employer-sponsored plans are governed by ERISA and must offer the same internal and external appeal rights. The DOL confirms you get at least 180 days to file, and if your appeals are exhausted, you may have a right to sue in federal court. Check your plan documents for the exact process.
Does it cost anything to appeal a denied claim?
Internal appeals cost nothing to file, and external review costs $0 under the federal process, though some state independent review organizations may charge up to $25, per Healthcare.gov. The main cost of appealing is your time and paperwork, not a filing fee. Don’t let cost concerns stop you.
A denied claim is a bill you may not have to pay. The appeal process is your structured, legally backed tool to shift that cost back to the insurer: start with the denial letter, follow the steps, and use every deadline. To keep more of your healthcare dollars, read our guide to hedging rising healthcare costs and explore our health finance tools.