How to appeal a health insurance denial

The first thing you’ll get is a dense, jargon-heavy letter that makes the denial sound permanent. It’s not. Buried in that letter is the reason code—usually a short phrase like ‘not medically necessary’ or ‘experimental treatment.’ That code is your target. Circle it. If you don’t understand it, call the insurer and ask for the full clinical policy bulletin that explains why they denied you. They have to send it to you within 30 days. I once had a client whose denial was overturned in 48 hours because the policy bulletin had a typo—it listed the wrong ICD-10 code. One phone call fixed it. Don’t assume the denial is correct. Verify the details.

Insurers deny claims when they’re missing information or when your doctor’s notes don���t match their criteria. Before you file an appeal, gather:

- Your medical records (ask your doctor for a full copy, not just the summary).

- A letter from your doctor explaining why the treatment was necessary. Make sure it cites the insurer’s own policy—doctors hate doing this, but it’s critical.

- Any peer-reviewed studies that support your case. PubMed is free and searchable.

- A timeline of your symptoms and treatments.

I had a client denied physical therapy for chronic back pain. The insurer said it was ‘maintenance care.’ We submitted a study showing that the exact therapy reduced hospitalizations by 30%. Denial overturned in two weeks. Evidence wins.

Every insurer has an internal appeal process. It’s free, and you have 180 days from the denial date to file. Don’t wing it. Use the insurer’s appeal form if they have one. If not, write a one-page letter that includes:

- Your name, policy number, and the claim number.

- The reason for denial (from the letter).

- A clear argument why the denial is wrong, with citations from their policy and your evidence.

- A specific request: ‘Please approve the claim for [procedure] as medically necessary.’

Send it certified mail. Keep a copy. The insurer has 30–60 days to respond. If they miss the deadline, the denial is automatically overturned in most states. I’ve seen this happen—don’t let them drag it out.

If the internal appeal fails, you can request an external review. This is a real shift. An independent third party reviews your case, and their decision is binding. You have 60 days to request it after the internal denial. The process varies by state, but you can find your state’s form on the Department of Insurance website.

Here’s the kicker: external reviewers overturn about 40% of denials. Why? Because insurers know they’re being watched. I had a client denied a $120,000 cancer drug. The external reviewer approved it in 10 days. No lawyer, no lawsuit. Just a form and persistence.

If your state doesn’t have a strong external review process, you can still request one through the federal government if your plan is self-funded (common with large employers). The form is on the CMS website.

If the external review fails, or if the insurer is dragging their feet, file a complaint with your state’s insurance commissioner. It’s free, and it forces the insurer to respond. The complaint form is usually one page. Include:

- Your policy number and claim number.

- A timeline of events.

- Copies of all denial letters and appeals.

- A clear explanation of why you think the denial is wrong.

The commissioner’s office will investigate. It’s not a guarantee, but it puts pressure on the insurer. I’ve seen denials overturned within weeks of a complaint being filed. It’s a low-effort way to escalate without a lawyer.

Most denials can be overturned without a lawyer. But if you’re dealing with a high-dollar claim (think $50,000+), a complex medical issue, or an insurer that’s breaking the law, it’s time to call one. Look for an attorney who specializes in ERISA or insurance bad faith. They usually work on contingency—you don’t pay unless you win.

Here’s the catch: lawyers won’t take cases they can’t win. If your appeal is weak, they’ll tell you to try the steps above first. I once referred a client to a lawyer for a $250,000 denial. The lawyer said, ‘File an external review first.’ The external review overturned the denial in two weeks. No lawsuit needed.

If you can’t find a lawyer, some nonprofits like the Patient Advocate Foundation offer free help. But don’t wait until the last minute—some deadlines are as short as 30 days.

If your denial is for an out-of-network service (like an ER visit or specialist), the No Surprises Act might help. This law bans balance billing for emergency care and some non-emergency services. If you got a surprise bill, you can dispute it through an independent dispute resolution (IDR) process.

Here’s how it works:

- You have 120 days from the bill date to file a dispute.

- The insurer and provider submit their proposed payment amounts.

- An arbitrator picks one.

The arbitrator usually sides with the insurer, but the process forces them to negotiate. I had a client who got a $45,000 ER bill reduced to $3,000 through IDR. It’s not perfect, but it’s better than paying the full amount. The form is on the CMS website.

Insurers lose paperwork. Deadlines slip through the cracks. Protect yourself by keeping a log of every interaction.

- Note the date, time, and name of the person you spoke to.

- Save all emails and letters.

- Send follow-ups in writing.

I had a client whose appeal was denied because the insurer ‘never received’ her doctor’s letter. She had a fax confirmation. The denial was overturned in 48 hours. If you don’t document it, it didn’t happen.

Use a spreadsheet or a notebook. Include:

- Date of interaction

- Method (phone, email, mail)

- Person’s name and title

- Summary of what was said

- Next steps and deadlines

This log will save you if the insurer tries to claim you missed a deadline.

I’ve seen denials overturned for claims that seemed unwinnable. One client was denied a $150,000 liver transplant because the insurer said it was ‘experimental.’ We submitted a letter from the doctor and two peer-reviewed studies. The denial was overturned in 10 days.

Here’s the truth: insurers deny claims because they know most people won’t appeal. The appeal process is designed to weed out the weak cases. If you have a strong case, you’ll win. If you don’t, you’ll lose. But you’ll never know unless you try.

The worst that can happen is they say no again. The best that can happen is you get the treatment you need and save thousands of dollars. It’s worth the hour it takes to file an appeal.