Health Insurance Claim Denied? What to Do Next (Step by Step)

You opened the mail (or the app), saw the word "denied," and your stomach dropped. Maybe it's a bill you thought was covered. Maybe it's a treatment you need. Either way, take a breath — a denial is not the final word. It's the start of a process you can actually work through.

Most denied claims can be appealed, and a meaningful share of denials are reversed when patients push back. The key is to act on the specific reason your claim was denied, not a vague sense of unfairness. This guide walks you through it, step by step, starting right now.

Step 1: Read the denial letter and find the EXACT reason

Your denial comes with a document — usually a denial letter and an Explanation of Benefits (EOB). The EOB is not a bill; it's a summary of what the insurer decided to pay and what it didn't. Read both carefully.

You're hunting for two things:

• The denial reason stated in plain language ("not medically necessary," "out-of-network," "prior authorization required," etc.).
• The reason code — a short letter/number code (often called a CARC, or Claim Adjustment Reason Code) that pins down the exact category of denial.

Write down the reason and the code exactly as they appear. Everything you do next responds to this specific reason. A generic "please reconsider" letter rarely works; a targeted rebuttal of the stated reason is what moves the needle.

Step 2: Find your appeal deadline — and don't miss it

This is the part people get wrong. There is a deadline to file an appeal, and it is printed on your denial letter. Find it now.

The window varies by plan. For many plans, the internal appeal deadline is somewhere around 180 days from the date of the denial notice — but do not rely on that number for your situation. Check the exact deadline and instructions on your letter, because plans differ and some are shorter.

A few practical notes:

• Calendar the deadline the moment you find it, and aim to file well before it.
• If your situation is urgent (you need care now), ask about an expedited appeal, which is meant to be decided much faster.
• Missing the deadline can cost you the right to appeal, so when in doubt, file early.

Step 3: Understand the common reasons (many are just paperwork)

It helps to know what you're up against. A large portion of denials are administrative — fixable errors, not judgments that your care wasn't worth it. Common reasons include:

• Not medically necessary — the insurer says the service wasn't required. This often comes down to documentation the insurer didn't have.
• Missing prior authorization — the treatment needed pre-approval that wasn't obtained or wasn't on file.
• Coding errors — a wrong or mismatched billing code. A single digit can trigger a denial.
• Out-of-network — the provider wasn't in your plan's network (sometimes a provider you reasonably believed was in-network).
• Missing or incomplete information — a form, a date, or a record didn't make it through.

The takeaway: many denials are reversed simply by supplying the right paperwork or correcting an error. Don't assume the "no" is about the merits of your care.

Step 4: Know how the appeal process works

There are typically two layers, and you usually go through them in order.

1. Internal appeal. You ask your insurance company to review its own decision. This is your first move and where many denials are resolved. You submit your appeal in writing (and sometimes by phone for urgent cases), and the insurer reconsiders.

2. External / independent review. If the internal appeal is denied, you can often request a review by an independent third party not connected to your insurer. Their decision is generally binding on the plan. Your final internal denial letter should explain how to request this and the deadline to do so.

Follow the sequence and the instructions on your letters. Each step has its own forms and timeframes.

Step 5: Gather your evidence

Before you write, collect everything in one place. A well-documented appeal is far more persuasive than a strong opinion. Pull together:

• The denial letter and EOB (with the reason and code you identified).
• Relevant medical records that support the care in question.
• A letter of medical necessity from your provider — a note from your doctor explaining why the treatment is needed for your condition. This is often the single most powerful document for "not medically necessary" denials. Ask your provider's office; they handle these regularly.
• Your plan's covered-benefit language — the section of your policy, Summary of Benefits, or member handbook showing the service should be covered. Quoting the plan's own words is hard to argue with.
• Any claim numbers, member ID, and dates of service, so the reviewer can find your file instantly.

Step 6: Write the appeal letter

Now you write — and the goal is to make the reviewer's job easy. Keep it organized, factual, and focused on the specific denial reason.

A strong appeal letter generally:

• Identifies the claim up front: your name, member ID, claim number, date of service, and the denial date.
• States the exact reason you're appealing (quote the denial reason and code).
• Rebuts that specific reason point by point. If it's "not medically necessary," cite the letter of medical necessity and records. If it's a coding error, point to the correct code. If it's a covered benefit, quote the plan language.
• Stays factual and calm. You don't need to be emotional or apologetic — clear and well-supported wins.
• Lists the documents you're enclosing so nothing gets overlooked.
• Asks clearly for the denial to be overturned and the claim paid.

Send it the way your letter instructs (mail, fax, or portal), keep a copy of everything, and note the date you submitted it.

Quick recap

• Read the denial letter and EOB; find the exact reason and reason code.
• Find your deadline on the letter and calendar it — internal appeals are often around 180 days, but check yours.
• Don't panic — many denials are administrative errors, not rejections of your care.
• Gather the denial letter, records, a letter of medical necessity, and your plan's benefit language.
• Write a focused appeal that rebuts the specific reason, then escalate to external review if needed.

One last note: this article is general information to help you get oriented — it is not legal, medical, or insurance advice, and no appeal outcome is guaranteed. Always follow the specific deadline and instructions on your own denial letter, and talk to your provider or a qualified professional about your particular situation. You've got a real path forward here. Take it one step at a time.