How to appeal a health insurance claim denial

Your right to appeal

Under the Affordable Care Act (ACA), you have the legal right to appeal any health insurance claim denial. This applies to all individual and employer group health plans, including marketplace plans, employer coverage, and Medicare Advantage. Insurers are required to follow a standardized appeals process.

Step 1: Understand the denial

When your claim is denied, you must receive a written Explanation of Benefits (EOB) or denial notice, the specific reason for denial, reference to the plan provisions or criteria used, instructions on how to appeal and the deadline, and notice of your right to request the clinical criteria used. Read it carefully, common reasons include "not medically necessary," "experimental/investigational," "out-of-network," "missing documentation," or "service not covered."

Step 2: Gather documentation

Before filing, collect your EOB showing the denial, medical records supporting the treatment, a doctor's letter of medical necessity, peer-reviewed medical literature if the service is denied as experimental, your plan's Summary of Benefits and Coverage (SBC) and Evidence of Coverage (EOC), and any previous authorization approvals for the same or similar services.

Step 3: File an internal appeal

Your first step is always an internal appeal, directly with your plan. The deadline is usually 180 days from the denial notice for ACA marketplace plans. Plans must respond within 30 days for pre-service denials, 60 days for post-service claims, and 72 hours for urgent care. Submit all documentation in writing, keep copies of everything, and note your submission date. If your health is at risk, request an expedited review, plans must respond within 72 hours.

Step 4: Request a peer-to-peer review

Before or during your internal appeal, ask your doctor to request a peer-to-peer review, which lets your doctor speak directly with the plan's medical reviewer. Many denials are resolved at this stage.

Step 5: External review (Independent Review Organization)

If your internal appeal is denied, you have the right to request an external review by an Independent Review Organization (IRO). The IRO is independent of your insurer, and its decision is legally binding. The deadline is usually four months after internal-appeal denial; cost to you is typically $0–$25; and IROs must decide within 45 days (standard) or 72 hours (expedited). For Medicare Advantage, request a Qualified Independent Contractor (QIC) review, then an Administrative Law Judge hearing.

Step 6: File a state insurance department complaint

In parallel with your appeal, consider filing a complaint with your state insurance commissioner. This creates a formal record and may trigger a regulatory review of the insurer's practices. Find your commissioner via our state directory.

Step 7: Seek additional help

Many disease-specific nonprofits offer free appeals assistance. ACA-funded state consumer-assistance programs help with appeals in many states. If your coverage is through work, your employer's HR department may intervene. For large claims, consult an ERISA or insurance attorney, many work on contingency.

How appeals data describes insurer behavior

The CMS Transparency in Coverage public-use files include not only claim-denial rates but also appeal-filing rates and appeal-overturn rates. Reading these three columns together turns a single denial-rate snapshot into a fuller picture. An insurer can have a high denial rate and a high overturn rate, aggressive initial adjudication that gets corrected on appeal, or a moderate denial rate with a very low overturn rate, suggesting denials that are administratively harder to challenge. Among the issuer-state rows in the data, appeal-overturn rates vary from under 5% to over 50%. A high overturn rate combined with a low appeals-filed rate can indicate that most policyholders do not pursue formal appeals even when they would likely succeed.

Don't be discouraged by an initial denial

Initial denials are common, and a substantial share are reversed when contested. Persistence pays: most denials that survive to external review were improperly denied. The same data row that lets you see how often a plan denies claims also lets you see how often those denials are reversed on appeal.