A denial letter can feel final, but it usually isn't. Insurance appeals have several stages, each with its own deadline, and the last one is decided by a reviewer outside your insurer. It helps to treat the appeal as a small project with documents, dates and follow-up. This guide builds on our FAQ My insurance denied coverage. What now?
Most denials are never appealed
KFF's analysis of HealthCare.gov marketplace plans found that insurers denied 19% of in-network claims in 2024, and fewer than 1% of denied in-network claims were appealed. When people did file an internal appeal, insurers upheld their original decision 66% of the time, which means about a third were overturned (KFF, March 2026 (external link)). Many people don't know the later steps exist: in a 2023 KFF survey, only 40% of consumers believed they had a legal right to appeal to a government agency or independent medical expert, and 51% weren't sure. Those figures come from marketplace plans; employer plans publish much less data.
The typical stages
- Find the exact denial reason. Denials cite a specific code or explanation, such as "not medically necessary," "step therapy not completed" or "excluded benefit." Your appeal has to answer that reason. A generic letter that ignores it is far less likely to work.
- File a first-level internal appeal. You have 180 days from the denial to file (healthcare.gov (external link)). Your prescriber sends the documentation that answers the denial reason: clinical notes, BMI and comorbidity history, prior treatments. The plan must decide within 30 days for a drug you haven't received yet, or faster if your health requires it.
- Use a second internal level if your plan has one. Some plans add a second internal review, sometimes by a different reviewer or medical director, before external review opens up.
- Ask for external review. If the internal appeal fails, you can ask for an independent review by an organization not tied to your insurer. You have 4 months from the final internal decision to request it, and your insurer is legally required to accept the reviewer's decision (healthcare.gov (external link)). Very few people get this far: KFF counted at least 5,881 external appeals from marketplace enrollees in 2024, about 4% of upheld internal appeals. Our guide on escalation paths beyond your insurer covers this and other outside options.
What gives an appeal its best chance
These are practical tips, not findings from a study. Answer the stated denial reason point by point instead of restating general medical need (see how to write an appeal letter). Back it with specific clinical documentation: lab values, BMI history, comorbidity diagnoses and prior treatments. A general letter of support on its own gives the reviewer much less to work with.
Keep track of every deadline, because appeal windows are strict and missing one can cost you the right to go further. If the first level fails, go to the next one; a denied internal appeal still leaves external review, and almost no one uses it. It also helps to have a prescriber's office that knows the process. Practices that handle GLP-1 prior authorizations and appeals regularly often know what documentation a given insurer or PBM responds to.
This article is general education, not medical, legal, or insurance advice. Coverage rules, appeal rights, and policy details vary by plan and location and change over time. Confirm specifics with your plan, prescriber, or a qualified advisor.