Claim Denied: How to Appeal Health Insurance
What Should You Do First When a Health Insurance Claim Is Denied?
Key Takeaway: A claim denial means the insurer processed the bill and refused to pay all or part of it. Your first job is to learn the reason code, confirm the appeal deadline, and decide whether you need a corrected claim from your provider or a formal member appeal.
Start with the paperwork in your hand. Your insurer sends an Explanation of Benefits after it adjudicates a claim. A separate denial letter may follow for services that need a formal adverse benefit determination. If you only received a phone call, ask the plan to put the decision in writing with the reason code and appeal instructions.
If you are unsure how to read the line items, see our guide on how to read an Explanation of Benefits. Match each denied service to the remark or reason code. Administrative denials such as missing information or coding errors may be fixed when your provider resubmits the claim. Clinical denials such as medical necessity or prior authorization require a member appeal with supporting records.
Mark the appeal deadline from your notice immediately. Federal rules give ERISA-covered employer plans specific claims and appeals procedures under ERISA, while ACA marketplace plans must provide internal and external review under Healthcare.gov appeal rules. Medicare uses a separate multi-level process on Medicare.gov.
Which Denial Reason Points to Which Action?
Key Takeaway: The reason code on your denial letter tells you what to fix. Coding and billing errors usually start with your provider. Medical necessity, prior authorization, and step therapy denials need a written appeal with clinical documentation.
| Denial type | What it usually means | First action |
|---|---|---|
| Medical necessity | Plan says the service or drug is not required for your diagnosis | Appeal with physician letter, clinical notes, and plan medical policy citations |
| Prior authorization | Service was performed without required pre-approval | Request retroactive authorization or appeal with urgency documentation. See how to appeal a prior authorization denial |
| Out-of-network | Provider is not in your plan network | Check emergency and facility-based protections under the No Surprises Act, then appeal with network access records if applicable |
| Coding or missing information | Claim data does not match records or is incomplete | Ask your provider to review and resubmit a corrected claim |
| Step therapy or formulary | Required cheaper drug trials were not documented | Appeal through your pharmacy benefit manager with prescriber records of prior drug trials |
| Plan exclusion | Service is excluded from your benefit package | Compare the denial to your Summary of Benefits and Coverage and appeal if the service should be covered under your tier |
How Long Do You Have to Appeal a Denied Claim?
Key Takeaway: The controlling deadline is on your denial notice, not a blog post. ERISA employer plans, ACA marketplace plans, and Medicare use different clocks and forms. Missing the internal appeal deadline can end your case before external review is available.
| Plan type | Typical internal appeal pattern | External review or next level |
|---|---|---|
| ERISA employer plan | Federal claims procedure rules require a full and fair review. Many plans allow up to 180 days from the adverse benefit determination for the first appeal, but confirm the date on your notice. | Voluntary external review may be offered. Self-funded plans are overseen by the U.S. Department of Labor, not state insurance departments. |
| ACA marketplace plan | ACA Section 2719 requires internal appeals with timelines disclosed on your denial notice. File through the plan portal or address listed on the letter. | External review through an independent review organization is available after internal appeals for qualifying cases under ACA and state law. |
| Medicare | Original Medicare, Medicare Advantage, and Part D each use plan-specific notices. Medicare.gov lists the redetermination and Level 1 appeal clocks on your Medicare Summary Notice or plan denial. | Higher Medicare appeal levels continue through Medicare.gov. Do not use commercial ERISA deadlines for a Medicare case. |
For a deeper walkthrough of appeal windows by plan type, read how long you have to appeal a health insurance denial. Submit at least several days before the printed deadline so portal uploads or mail delivery do not cut your time short.
What Documents Should You Attach to Your Appeal?
Key Takeaway: Appeals move when you answer the exact reason code with records a reviewer can verify. Build a packet the insurer can open without calling you for missing pages.
- Denial letter, Explanation of Benefits, and claim number
- Insurance card, member ID, and Summary of Benefits and Coverage
- Medical records, test results, and operative reports when the denial is clinical
- Physician letter or letter of medical necessity tied to the plan medical policy
- Prior authorization history and pharmacy records for step therapy or formulary denials
For ERISA employer plans, you can request the claim file the plan relied on when it denied coverage. Submit that request in writing to the plan administrator listed on your denial letter. Review those documents before you write your appeal so you respond to the insurer's actual rationale.
Use AppealFlow's free health insurance appeal letter generator to draft a structured letter that cites your denial reason, member information, and attached exhibits. Edit the draft with your provider before you upload it to the plan portal.
Weak vs. Strong Appeal Language
Key Takeaway: Reviewers scan for the reason code, dates, and clinical support. Vague frustration without records rarely changes a denial. Specific citations to plan policy and attached evidence do.
| Weak statement | Strong statement |
|---|---|
| “My doctor ordered this test. Please pay.” | “Denial code CO-50 for lumbar MRI on 3/12/2026. Attached: six weeks of conservative therapy notes, physician letter, and imaging appropriateness criteria referenced in your medical policy section 4.2.” |
| “I need this medication.” | “Formulary exception denied for brand drug after documented failure of required step-therapy agents. Attached: pharmacy claims history and prescriber letter listing contraindications to the preferred alternatives.” |
| “This denial is unfair.” | “Claim #88421, denial dated 7/20/2026. I request the claim file under ERISA claims procedure rules and submit this Level 1 appeal with operative report and pathology results attached. Appeal deadline per notice: 1/16/2027.” |
Need an Appeal Letter for a Denied Claim?
AppealFlow drafts regulation-informed appeal letters for health insurance denials. Edit live, then download as PDF or Word.
How Do You Request External Review if Internal Appeal Fails?
Key Takeaway: External review puts your records before an independent reviewer after internal appeals are exhausted. ACA marketplace and many state-regulated plans must offer it. Medicare and many ERISA self-funded plans follow different paths.
Internal appeals are decided by the same insurer that issued the denial, usually by a different unit. When that review upholds the denial, qualifying ACA and state-regulated plans must allow external review under Healthcare.gov external review rules. Your denial letter should name the contact or portal for that request.
For step-by-step filing instructions, see our guide on how to request external review after an insurance denial. Expedited external review may be available when delay would seriously jeopardize your life or health. Ask the plan how to mark an urgent request on your form.
What If Your Provider Bills You While You Appeal?
Key Takeaway: A denied claim does not always mean you owe the full chargemaster rate. Ask billing to hold the account during an active appeal, request an itemized bill, and compare charges to your Explanation of Benefits.
Providers often send statements before your appeal window closes. Call the billing office, reference your denial letter, and ask them to flag the account as appeal pending. Keep a log of every call with the date, representative name, and confirmation number.
If the appeal succeeds, the insurer issues a corrected Explanation of Benefits and pays the provider per contract. You should receive an updated statement showing only your allowed cost-sharing. If you already paid more than that amount, request a refund with the corrected EOB attached.
Frequently Asked Questions
Common questions about what to do when a health insurance claim is denied and how to appeal.
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Disclaimer: This article is for educational purposes only and does not constitute medical or legal advice. AppealFlow is not an insurance company or law firm. Plan terms, appeal deadlines, and coverage rules vary. Review your denial notice and plan documents, and consult a licensed professional when appropriate. For emergencies, call 911. See our full disclaimer.