What to Do When Insurance Denies Your Claim: Day-by-Day Action Plan

A health insurance denial can feel like a final verdict. It's not. The law gives you specific rights to challenge denials, and a significant number of appeals succeed. The key is knowing exactly what to do and in what order, starting from the day you receive the denial.

Day 1: Do Not Accept the Denial

The worst thing you can do is pay the bill and move on. Insurance companies deny claims for many reasons — some legitimate, many not. Coding errors, missing documentation, and incorrect plan application are common. Even when the denial is based on medical judgment, that judgment can be challenged with the right clinical evidence.

Before you do anything else, write down the date you received the denial. Every deadline in your appeal is measured from this date.

eob-in-writing">Day 1-2: Get the Denial Letter and EOB in Writing

If you received a phone call or a brief portal notification, request the formal denial letter in writing immediately. Call the insurer's member services line and demand:

1. A written denial letter explaining the specific reason for the denial
2. The clinical criteria or plan provisions used to make the decision
3. Information about your appeal rights and deadlines

Also request your Explanation of Benefits (EOB) — the detailed statement that shows what was submitted, what was processed, and what was denied. Compare the EOB to your actual medical bills. Billing errors (wrong CPT code, duplicate submission, wrong patient ID) are surprisingly common and can be fixed without a formal appeal.

Day 2-3: Identify Your Plan Type — This Changes Everything

The rules governing your appeal depend entirely on what type of health plan you have:

ERISA employer-sponsored plans: If you get health insurance through your job (and your employer is not a government entity or church), your plan is almost certainly governed by ERISA — a federal law. ERISA gives you 180 days to file an internal appeal and access to federal court if the insurer acts improperly. State insurance laws generally do not apply.

ACA marketplace or individual plans: Purchased directly from an insurer or through healthcare.gov. Governed by both federal ACA rules and state insurance law. State insurance commissioner complaints are available.

Medicaid/CHIP: State-administered. Appeal rights vary significantly by state. Contact your state Medicaid office for the correct appeal process.

Medicare: Has its own appeal process with five levels — redetermination, reconsideration, ALJ hearing, Medicare Appeals Council, and federal court.

Fully insured small group plans: Regulated by state law. Complaints to the state DOI are effective.

Check your insurance card, benefits booklet, or Summary Plan Description if you're unsure. The term "self-funded" or "self-insured" appearing anywhere indicates an ERISA plan.

Day 3-5: Review Your Plan Documents

Pull out your Summary of Benefits and Coverage (SBC) and the full Summary Plan Description (SPD) or Evidence of Coverage. Find the specific exclusion or limitation the insurer cited in the denial. Sometimes you'll discover:

• The exclusion doesn't apply to your situation
• The denial misquoted the plan language
• Your plan has an exception process you weren't told about
• The treatment actually is covered, and the claim was miscoded

Highlight every relevant passage. You'll cite these in your appeal.

Day 5-7: Call Your Doctor

Your physician is your most important ally. Contact them immediately and:

• Tell them the claim was denied and the specific reason
• Ask them to write a Letter of Medical Necessity (LMN) if the denial is based on medical necessity
• Request a complete copy of your relevant medical records
• Ask if they're willing to do a peer-to-peer review with the insurer's medical reviewer
• Ask if they've dealt with this insurer's denial process before — many specialists have staff experienced with specific insurer requirements

Your doctor's office may have an appeals coordinator who handles these cases regularly. Use that resource.

Week 1-2: File Your Internal Appeal

Gather all your documentation — the denial letter, EOB, plan documents, physician letter, clinical guidelines — and write your internal appeal letter. The letter should:

• State your identifying information and the denied claim clearly
• Reference the exact denial reason using the insurer's own language
• Present the clinical and contractual arguments for coverage
• Include all supporting documentation
• Request a complete copy of your claim file (you are legally entitled to this)
• State that you reserve all rights under ERISA (if applicable) and applicable state law

Submit by certified mail and through any other required channel (fax, online portal). Keep proof of every submission.

Week 2-4: Follow Up and Request Peer-to-Peer Review

If you haven't received a decision and you're approaching the insurer's legal deadline, follow up in writing and document the follow-up. Ask your physician to request a peer-to-peer review with the insurer's medical reviewer — this is a direct physician-to-physician call that can overturn medical necessity denials quickly, sometimes before the formal appeal is even decided.

If the Internal Appeal Is Denied: Escalate Immediately

You now have two paths to pursue simultaneously:

1. External/Independent Medical Review: File within 4 months of the internal appeal denial. An independent physician reviews your case, and the insurer must comply with the outcome.

2. State insurance commissioner complaint: File with your state DOI to create a formal record and potentially trigger regulatory action.

For large claims or if you believe the denial was in bad faith, consult an insurance attorney. Many work on contingency for health insurance cases.

Fight Back With ClaimBack

Most people don't know where to start after a denial — and insurers count on that. ClaimBack turns the confusion into a clear action plan. Answer a few questions about your denial, and ClaimBack builds your complete appeal package, identifies your strongest legal arguments, and guides you through every submission step.

You have more rights than you think. ClaimBack makes sure you use them all.

Start My Free Appeal →

Related Reading

• How to Write an Insurance Appeal Letter
• What Is Medical Necessity?
• Internal vs External Insurance Appeal