Claim denial
Updated September 30, 2026
Definition
When your health plan refuses to pay for all or part of a service. Your plan must tell you why in writing, and you have the right to appeal.
A claim denial means your health plan won't pay for some or all of a service. Your explanation of benefits (EOB) shows the denied amount and a code or note with the reason. Your plan must also explain the denial in writing and tell you how to appeal.
Plans deny claims for many reasons. The service may not be covered, the provider may be out-of-network, or the plan may say the care wasn't medically necessary. Some denials come from paperwork problems, like a wrong code or missing information.
Try not to pay a denied amount until you know the reason. A provider can often fix and resend a claim with an error. For other denials, you can file an internal appeal within 180 days of the notice. Start with insurance didn't pay my medical bill.
Related terms
Guides that use this term
- GuideInsurance didn't pay my medical bill: what to do nextInsurance didn't pay your medical bill? Find out why, match the denial code to the fix, and learn when to ask for a rebill and when to file an appeal.
- GuideDenial codes on your EOB, explainedWhat do CO-45, PR-1, and CO-16 mean? Look up common claim denial codes, learn who's responsible for each amount, and see what to do about each one.
Sources
- Internal appeals, HealthCare.gov. Accessed September 30, 2026.
- Appeal (glossary), HealthCare.gov. Accessed September 30, 2026.
- Claim adjustment reason codes, X12. Accessed September 30, 2026.
This is general information, not legal or medical advice. Rules can depend on your plan and your state. Romi Care isn't an insurer, law firm, collection agency, or government program.