Nivellark · U.S. patient resource
A denial letter can use insurance terms that are hard to untangle. This glossary explains common terms using official federal consumer guidance and points to the sources behind each explanation.
Government sources checked October 20, 2026
Plain-language definitions
A request for payment that you or your health care provider submits to an insurer for items or services you think your plan covers.
Context: The plan’s process and the information it asks for can differ. Check the instructions for your coverage and the service in question.
Sources for Claim
A plan decision not to provide or pay some or all of the cost of a health service. The notice should explain the reason and how to dispute the decision.
Context: A denial can have different reasons, such as a service not being a plan benefit or a plan saying it was not medically necessary. The reason stated in your notice matters.
Written information from a health plan that explains a claim denial and tells you how you can challenge the decision.
Context: Keep the complete notice. The appeal route, required steps, and deadline depend on the coverage and decision; follow the instructions in the notice.
Sources for Denial notice or denial letter
A summary from a health plan showing charges for care and how much the plan and patient may pay. An EOB is not a bill.
Context: An EOB explains how a claim was processed; it is separate from a provider’s bill. Original Medicare uses a different notice called a Medicare Summary Notice (MSN).
Sources for Explanation of Benefits (EOB)
A request to have a health plan reconsider a decision, such as refusing to pay a claim or ending coverage.
Context: Which appeal steps are available and how to request them depend on the type of plan or program. A request for review does not promise a different result.
A request for the health plan to review its own decision again.
Context: Forms, deadlines, and review steps depend on the plan and coverage rules. Medicare has its own program-specific appeal route.
Sources for Internal appeal
A review of certain health-plan decisions by an independent reviewer outside the insurer.
Context: Not every denial qualifies. The process and who handles it may depend on your plan and state; check the final notice for the route and deadline that apply.
Sources for External review
Health care services or supplies needed to diagnose or treat an illness, injury, condition, disease, or its symptoms, and that meet accepted standards of medicine.
Context: When a notice uses this phrase, it describes the plan’s stated reason. Look at the plan language and review information named in the notice; the phrase alone does not establish what care is appropriate for you.
Sources for Medically necessary
A health plan’s decision, made before some services or prescriptions, about whether the plan considers them medically necessary under its rules.
Context: Plans may require prior authorization for some services, and an authorization is not a promise that the plan will pay. Requirements depend on the service and coverage.
Sources for Prior authorization (preauthorization)
Under certain employee benefit-plan rules, this term generally includes a denial, reduction, termination, or failure to provide or pay a benefit, in whole or in part.
Context: This is not a label used for every type of coverage or every denial notice. The cited Department of Labor guidance concerns group health plans; other coverage, including Medicare, has different notices and appeal procedures.
Sources for Adverse benefit determination
For general steps after a health plan denial, read the health-insurance appeal guide.