How to appeal a denied claim — by insurer
Every payer denies differently. Pick yours below for the deadlines that apply, the denial codes that show up most on its EOBs, and a real example of a charge that got reversed.
The rights you have with every plan
- You generally have at least 180 days from the date on your denial notice (EOB) to file an internal appeal with your insurer.
- The insurer must decide standard internal appeals within 30 days for pre-service claims and 60 days for care you already received.
- Urgent cases get an expedited review — typically within 72 hours.
- If the internal appeal fails, you can request an independent external review, usually within 4 months of the final internal denial. The external reviewer's decision is binding on the plan.
- Self-funded employer plans follow ERISA rules; fully insured plans also fall under your state insurance department, which can be a second place to complain.
Choose your insurer
- UnitedHealthcareUHCUnited Healthcare
The largest US commercial insurer, with heavy use of prior authorization and automated medical-necessity review.
- AetnaAetna CVS HealthAetna Better Health
CVS Health-owned insurer covering employer, marketplace, Medicare and Medicaid plans across most states.
- CignaCigna HealthcareEvernorth
National employer-focused insurer; many Cigna cards sit on top of self-funded employer plans governed by ERISA.
- Blue Cross Blue ShieldBCBSAnthem
A federation of independent state licensees — your appeal rights and addresses depend on which Blue plan issued your card.
- HumanaHumana Gold PlusHumana Medicare
Predominantly a Medicare Advantage insurer, so most Humana denials follow CMS appeal rules rather than ERISA.
- Kaiser PermanenteKaiserKP
An integrated system where the insurer and the provider are the same organization — which changes how disputes work.
- Medicare (Original)Part APart B
Federal coverage with its own five-level appeal ladder, starting from the Medicare Summary Notice rather than an EOB.
- MedicaidState MedicaidMolina
State-run coverage with the strongest patient protections against balance billing — and the shortest appeal clocks.
Insurance appeal questions, answered
How long do I have to appeal a health insurance denial?
Most commercial plans give you at least 180 days from the date on your Explanation of Benefits to file a first-level internal appeal. Medicare Advantage plans typically allow 60 days, and Medicaid fair-hearing windows can be as short as 30 days. The deadline printed on your denial notice always governs.
What are my chances of winning an insurance appeal?
Far better than most people assume, because a large share of denials are administrative — a missing prior-authorization number, a wrong modifier, or a claim sent to the wrong payer. Those get corrected routinely. Medical-necessity denials are harder but are the exact category independent external reviewers were created to handle.
What is an external review and when can I use it?
After your insurer issues a final internal denial, you can ask for an independent external review — usually within 4 months. The reviewer does not work for the plan, and its decision is binding on the insurer.
Do I appeal the insurer or the hospital?
It depends on the denial code. Codes starting with CO (contractual obligation) are usually the provider's write-off and get fixed by the billing office; PR (patient responsibility) codes are the ones you appeal with the insurer. Our denial code directory tells you which is which for each code.
Does a written appeal work better than calling?
Calling can fix obvious clerical errors quickly, but only a written appeal starts the legal clock and creates a record you can escalate to external review. Call first if you like, then always follow up in writing.
Keep going
Informational tool — not legal, medical, or financial advice.