How to Appeal an Insurance Denial: A Complete Step-by-Step Guide

Understand Why Your Claim Was Denied

Before you can fight a denial, you need to understand the reason behind it. Common denial reasons include:

• Not medically necessary — The insurer doesn't believe the treatment was required
• Out of network — The provider isn't in your plan's network
• Prior authorization missing — The treatment wasn't pre-approved
• Coding errors — Incorrect CPT or diagnosis codes were submitted
• Experimental/investigational — The insurer considers the treatment unproven
• Duplicate claim — The insurer believes the claim was already submitted

Your Explanation of Benefits (EOB) or denial letter will include a specific reason code. Read it carefully — this is what you'll need to address in your appeal.

Know Your Rights Under the ACA

Many health plans are required to offer an appeals process and, in many cases, an independent external review right under federal and state rules (including ACA rules for many non-grandfathered plans). Under common federal requirements:

• Insurers must tell you why they denied your claim
• You have the right to an internal appeal reviewed by someone who wasn't involved in the original decision
• If the internal appeal fails, you can request an independent external review
• For urgent care, you can often request an expedited review (commonly within ~72 hours)

Step 1: File an Internal Appeal

This is your first formal challenge to the denial. Here's what to do:

1. Call your insurer to confirm the appeal process and deadline (often up to 180 days from denial, but it varies)
2. Request your complete claim file — you're entitled to it
3. Submit a written appeal letter addressing the specific denial reason
4. Include supporting documentation (medical records, doctor's letter, clinical studies)
5. Send everything via certified mail and keep copies of everything

Step 2: Gather Supporting Evidence

The strength of your appeal depends on your evidence. Collect:

• Medical records documenting your condition and treatment history
• Letter of medical necessity from your treating physician
• Clinical guidelines supporting the treatment (e.g., from medical societies)
• Peer-reviewed studies showing the treatment's effectiveness
• Your plan's Summary of Benefits showing the treatment should be covered

Step 3: Write a Strong Appeal Letter

Your appeal letter is the centerpiece of your case. It should:

• Reference your policy number, claim number, and date of service
• Clearly state you are appealing the denial
• Address the specific reason for denial with counter-evidence
• Cite your plan's coverage terms
• Include supporting clinical evidence
• Be professional, factual, and concise

Writing an effective appeal letter is the hardest part for most people. That's where technology can help.

Step 4: Request an External Review

If your internal appeal is denied, you may have the right to an independent external review. This means a third-party reviewer — not employed by your insurer — will evaluate your case. In some datasets, external reviews overturn a meaningful share of denials.

Your insurer is required to tell you how to request an external review in their denial letter.

Important Deadlines to Know

Important: These are common timelines under ACA-style rules for many plans, but employer plans, Medicare/Medicaid, and state-specific rules can differ. Always follow the deadlines in your denial letter.

Don't miss your deadlines. Once they pass, you may lose your right to appeal entirely.

How AI Can Help You Win Your Appeal

Writing a persuasive, medically accurate appeal letter is challenging — especially when you're already dealing with a health issue. MedAppeals uses AI to generate professional appeal letters tailored to your specific denial reason, diagnosis, and insurance plan.

• Upload your denial letter and medical records
• AI analyzes the denial reason and generates a customized appeal
• Letters are structured with clear medical necessity arguments tailored to your denial
• HIPAA-compliant and secure