How to Appeal a Denied Health Insurance Claim

If you’ve ever opened a letter from your health insurance company and seen the words “claim denied,” you know how frustrating—and overwhelming—it can feel.

Medical bills add up fast, and many people don’t realize that insurance denials are often reversible if you know how to appeal them correctly.

Below, we explain the difference between an internal appeal and an external review, what to gather, how to write an appeal letter, how Medicare appeals work, and where to get free help if you’re facing a denied health insurance claim.

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Why Health Insurance Claims Get Denied (More Often Than You Think)

Health insurance claims are denied for many reasons, including:

• “Medical necessity” not clearly documented
• Prior authorization missing or incomplete
• Coding or administrative errors
• Policy exclusions or unclear plan language
• Step-therapy or formulary restrictions

The key thing to understand is this:

👉 A denial is not the same as a final decision.

Under U.S. health insurance rules, consumers typically have the right to appeal, and many denials are overturned when appeals are done properly.

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Internal appeal vs. external review: what’s the difference?

Under the Affordable Care Act, HealthCare.gov describes two ways to appeal a denied health insurance claim. First, you ask your insurer to take a second look. That’s an internal appeal. If the insurer still says no, you can ask an independent third party to decide. That’s an external review.

The table below shows the key federal timelines from HealthCare.gov’s internal appeals and external review pages. Your denial letter may list your plan’s exact dates.

External review applies to denials that involve medical judgment, such as whether care is medically necessary. It also covers denials for “experimental” treatment and cancellations based on claimed false information in your application.

The result is binding on the insurer. HealthCare.gov says your insurer is required by law to accept the external reviewer’s decision. Review through the federal process is free. A state process can charge no more than $25.

What if your care is urgent?

You don’t always have to wait for the full internal process. HealthCare.gov lists a 72-hour timeline for urgent care cases. It also says that in an urgent situation, you can ask for an external review at the same time as your internal appeal.

Ask your doctor to explain in writing why waiting the normal time would put your health at risk. A short, specific letter about the danger of delay gives the reviewer a clear reason to move fast.

When you call the insurer, use the words “expedited” or “urgent” and ask how to send records fast. Write down the date, time and name of each person you speak with.

What should you gather before you appeal a denied health insurance claim?

A strong appeal is mostly about paperwork. Before you write anything, collect these items in one folder:

• The denial letter or explanation of benefits. It states the reason for the denial and your appeal deadlines.
• Your claim file. Ask the insurer or plan for the records it used. Employer plans under ERISA must give you these for free on request.
• Your plan’s coverage language. Find the section of your policy or plan booklet that covers the service.
• A letter from your doctor. HealthCare.gov gives it as an example of extra information to send with an appeal.
• Medical records. Include test results, notes and past treatments tried.
• A call log. Note the date, time, name and reference number for every call.

Then mark your deadline on a calendar. Count from the date you received the denial, and give yourself a few weeks of cushion. Missing a deadline is one of the few mistakes that can end an appeal before anyone reads it.

How do you write a health insurance appeal letter?

HealthCare.gov says you can use your insurer’s forms or write a letter with your name, claim number and insurance ID number. A clear letter makes the reviewer’s job easier. Here is a simple outline. It is a starting point, not legal advice.

1. Header: your name, address, phone, member ID, group number and claim number. Add the date and the insurer’s appeals address from your denial letter.
2. Opening line: “I am requesting an internal appeal of the denial dated [date] for [service or drug].”
3. The denial reason: quote the reason in the insurer’s letter, word for word.
4. Why it should be covered: two or three short points. Tie each one to your records or your plan’s own coverage language.
5. Your doctor’s support: mention the attached letter of medical necessity.
6. What you’re asking for: “Please reverse the denial and cover [service].”
7. Attachments list: denial letter, doctor’s letter, records, plan pages, receipts.

Keep it to one or two pages. Stick to facts, not frustration. Send it in a way you can track, and keep copies of everything you send, as HealthCare.gov advises.

Does your employer’s plan follow different rules?

Most health plans from private employers are governed by a federal law called ERISA, which the U.S. Department of Labor oversees. This includes self-funded plans, where the employer pays claims itself and an insurer only runs the paperwork. Your plan documents or HR team can tell you which type you have.

The Department of Labor’s guide, Filing a Claim for Your Health Benefits, lists key rights:

• You have at least 180 days to appeal. Your Summary Plan Description may allow longer.
• You can ask for copies of documents and records relevant to your claim for free.
• Plans that aren’t grandfathered under the ACA must offer external review by an independent party. Your denial notice explains how.
• Your denial notice must describe your right to go to court to recover benefits due under the plan.

The guide notes exceptions for plans sponsored by governments and most religious groups. For help, contact the Employee Benefits Security Administration at 1-866-444-3272 or askebsa.dol.gov.

One practical tip: before you appeal, ask the plan for your full claim file. Seeing exactly what the reviewer saw helps you answer the denial point by point.

How do you appeal a denied Medicare claim?

Medicare has its own process with five levels. If you have Original Medicare, you start with the Medicare Summary Notice (MSN) that lists the denied item. You must file by the date on the MSN. CMS gives you 120 days from receiving the initial decision.

Sources: Medicare.gov for the levels and filing times, and CMS for the 2026 amounts at the ALJ level and court level. Each “time to file” counts from when you get the decision at the level before.

In a Medicare Advantage plan, you must file the first appeal within 65 days of the plan’s denial notice. If the plan upholds its denial, it automatically sends your case to an Independent Review Entity (Medicare.gov). For any Medicare appeal, you can call 1-800-MEDICARE for help.

Where can you get free help with an appeal?

You don’t have to do this alone. Free help is available in most places:

• State Consumer Assistance Programs (CAPs). Many states run programs that help people with health insurance problems by phone, mail, email or in person. CMS keeps a state-by-state map. If your state has no CAP, the map points you to other resources.
• Your state insurance department. It oversees insurers licensed in your state and can explain your state’s external review process.
• The Department of Labor. For employer plans covered by ERISA, call EBSA at 1-866-444-3272.
• 1-800-MEDICARE. For Original Medicare, Medicare Advantage and Part D appeals.
• Your doctor’s office. Many offices handle appeals often and can send records and a letter of medical necessity.

For a high-dollar or complex denial, a health care attorney or patient advocate may also help. If you want to appeal a denied health insurance claim on your own first, these free resources are a good place to start.

What does a successful appeal look like? A hypothetical example

This is a hypothetical example to show the steps. It is not based on a real case.

Dana, 52, has an ACA marketplace plan. Dana’s doctor orders an MRI, and the insurer denies it as “not medically necessary.” The denial letter is dated March 1.

1. Week 1: Dana calls the insurer, asks for the full reason and requests the claim file, noting the 180-day internal appeal deadline from the date the letter arrived.
2. Week 2: The doctor writes a letter explaining the symptoms, the treatments already tried and why the MRI is needed now.
3. Week 3: Dana sends a two-page appeal letter using the outline above, with the doctor’s letter and records attached.
4. Within 30 days: Because the MRI hasn’t happened yet, the insurer must decide within 30 days. It upholds the denial.
5. Next step: Dana requests an external review well within 4 months. The independent reviewer decides within 45 days and overturns the denial. By law, the insurer must accept that decision and cover the MRI.

Not every appeal succeeds. But Dana’s steps show what helps most: meet each deadline, answer the stated reason directly and let your doctor explain the medical need. These same steps apply whenever you appeal a denied health insurance claim.