April 10, 20263 min read

How to Appeal an Insurance Denial

You went to the doctor. You had a procedure. Your insurance was supposed to cover it. Then the letter arrives: claim denied.

It feels final. It's designed to feel final. But here's the truth the insurance industry doesn't want you to know: denials are not the end of the conversation. They're the beginning of a negotiation — and the data is on your side.

Studies show that more than 50% of appealed insurance denials are overturned. Half. And yet fewer than 1% of denied claims are ever appealed. Insurance companies are making billions from the gap between what people are owed and what they're willing to fight for.

Don't be in the 99%.

Why Claims Get Denied

Understanding why your claim was denied is the first step to overturning it. The most common reasons include:

Prior authorization not obtained — your provider didn't get pre-approval
Out-of-network provider — you saw a doctor outside your plan's network
Medical necessity — the insurer says the treatment wasn't necessary
Coding errors — the wrong CPT or diagnosis code was submitted
Missing information — the claim was incomplete or had errors
Timely filing — the claim was submitted past the deadline

Look at your denial letter closely. It must tell you why the claim was denied and how to appeal. If it doesn't, that itself may be a violation.

The Appeals Process: Step by Step

Step 1: Read the Denial Letter Carefully

Your denial letter contains the specific reason for denial, the plan provisions they're citing, and instructions for filing an appeal. Read every word. The reason matters because your appeal needs to address it directly.

Step 2: Gather Your Documentation

Build your case. Collect:

The denial letter
Your EOB (Explanation of Benefits)
Medical records related to the treatment
A letter from your doctor explaining why the treatment was medically necessary
Any prior authorization records
Your insurance plan's Summary of Benefits

Your doctor's letter is often the most important piece. Insurers deny claims for lack of medical necessity — your doctor can counter that with clinical evidence.

Step 3: Write Your Appeal Letter

Your appeal letter should:

Reference the claim number and date of service
State clearly that you are appealing the denial
Address the specific reason for denial with evidence
Cite your plan's coverage provisions
Include supporting documentation
Request a written response within the required timeframe

Be factual, specific, and firm. Don't beg — assert your rights.

Step 4: Submit and Track

Send your appeal via certified mail to the address listed in the denial letter. Keep copies of everything. Note the date — your insurer typically has 30 days (60 for urgent cases) to respond to an internal appeal.

Step 5: Escalate If Needed

If your internal appeal is denied, you have the right to an external review — an independent third party reviews your case. Under the ACA, all marketplace and employer plans must offer external review.

You can also file complaints with your state insurance commissioner and the Department of Health and Human Services. These regulators have real teeth, and insurers take their inquiries seriously.

Common Mistakes to Avoid

Missing the deadline — most plans give you 180 days to appeal, but don't wait
Being vague — your appeal must address the specific denial reason
Not including your doctor — a physician's support letter dramatically improves your odds
Giving up after the first denial — there are multiple levels of appeal for a reason

Let BillFighter Handle the Paperwork

Insurance appeals are winnable — but the paperwork is exhausting. BillFighter generates personalized insurance appeal letters that address the specific denial reason, cite relevant regulations, and include the right language to get results. Send them via certified mail with one tap.

Your claim was denied. That doesn't mean it's over. Start your appeal →