When a health insurance claim is denied, most people simply pay the bill or give up on the treatment. In fact, fewer than 1% of denied claims on HealthCare.gov plans are appealed. But you have a legal right to challenge a denial, and to have an independent reviewer look at your case. Here is how the process works.

Step 1: Understand why you were denied

Your insurer must tell you in writing why it denied your claim. It has 15 days to respond to a prior authorization request, 30 days for care you have already received, and 72 hours for urgent care.

Read the letter and your Explanation of Benefits carefully. The reason for the denial tells you what evidence you will need. A billing error may only need a corrected claim, while a "not medically necessary" denial needs your doctor's support.

Step 2: Gather your evidence

A strong appeal includes:

Your name, claim number and health insurance ID number
The insurer's appeal form, or a short letter asking for a review
A letter from your doctor explaining why the treatment was needed
Copies of the denial letter, Explanation of Benefits and relevant medical records
Notes from every phone call: the date, time, the person's name and what was said

If you want your doctor or someone else to file for you, include a signed form giving them permission.

Step 3: File an internal appeal

An internal appeal asks your insurance company to take a full, fair second look at its decision. You must file within 180 days of receiving the denial notice.

The insurer then has:

30 days to decide on care you have not received yet
60 days to decide on care you have already received
No more than 4 business days in urgent cases

Keep a copy of everything you send, and send it in a way you can track.

Step 4: Ask for an external review

If your internal appeal is denied, you can request an external review. An independent reviewer, not your insurance company, decides whether the claim should be paid. Your insurer is required by law to accept the reviewer's decision.

Deadline: Within 4 months of the insurer's final decision
Decision time: No later than 45 days, or 72 hours for urgent cases
Cost: Free under the federal process, and no more than $25 under other processes

If waiting could seriously harm your health, you can request an external review at the same time as your internal appeal.

Step 5: Get help if you need it

You do not have to do this alone. Your state's Consumer Assistance Program or Department of Insurance can explain your rights, and in some cases help file the appeal. Your doctor's office may also have staff who handle appeals regularly.

The bottom line

An appeal takes some paperwork, but it can save you hundreds or even thousands of dollars. Know your deadlines, back up your case with your doctor's support, and remember that an independent review is available if your insurer still says no.