How to Appeal an Insurance Denial: A Complete Guide

Step 1: Read Your Denial Letter Carefully

Your denial letter is the roadmap for your appeal. Don't just skim it; analyze it. Look for these key pieces of information:

• The Exact Reason for Denial: Insurers must provide a specific reason. It could be "not medically necessary," "experimental treatment," "out-of-network provider," or a coding error.
• Denial Codes: The letter will reference specific codes used to justify the denial. You can look these up to better understand the rationale.
• Your Appeal Deadline: This is critical. Federal law (the ACA) generally gives you 180 days from the date of denial to file an internal appeal, but you should always confirm the exact date in your letter.
• Instructions for Appealing: The letter must tell you how to start the appeal process.

Along with the letter, review your Explanation of Benefits (EOB). It provides a detailed breakdown of what the insurer paid and what you owe, which can offer additional clues.

Step 2: File Your Internal Appeal

The internal appeal is your first formal challenge, handled directly by your insurance company. Your goal is to provide new information or a stronger argument that convinces them to reverse their decision.

Your appeal should always be in writing. We recommend using our Appeal Letter Builder to create a professional, structured letter. A strong appeal package includes:

• A Formal Appeal Letter: Clearly state that you are appealing the decision. Reference your policy number, claim number, and the date of denial.
• A Letter of Medical Necessity from Your Doctor: This is one of the most powerful tools in your arsenal. Ask your doctor to write a letter explaining why the treatment is medically necessary for your specific condition, referencing your medical history and clinical practice guidelines.
• Supporting Medical Records: Include relevant test results, chart notes, and any other documents that support your case.
• Peer-Reviewed Studies: If your denial is for an "experimental" treatment, include copies of scientific studies from reputable medical journals that show the treatment is safe and effective.

Send your appeal via certified mail with a return receipt requested. This provides proof that the insurer received it and on what date.

Step 3: Request an Independent External Review

If your internal appeal is denied, you have the right to an external review. This is where your case is reviewed by an independent third party—an Independent Review Organization (IRO)—with no connection to your insurance company. This is a powerful consumer protection guaranteed by the ACA.

You must typically request an external review within 60 days of the final internal denial. The IRO's decision is legally binding on the insurance company. This is not an optional step for them; if the IRO sides with you, the insurer must pay the claim.

The success rate for patients in external reviews is surprisingly high, often between 40-60%, because the decision is based purely on medical evidence, not the insurer's internal policies. Learn more about the external review process here.