Insurance denials and appeals, explained like you're 5

Why claims get denied

Five common reasons, and what an appeal needs for each.

1. 01

   No prior authorization

   Prior authorization means the plan wanted approval before the care happened. The plan may deny payment when that approval was missing or did not cover the care.

   What the appeal needs

   • The plan required approval before the service.
   • The office has proof it requested approval.
   • The letter describes a missing or incomplete approval.

   Watch out for

   • Ask whether approval covered this service, date, and setting.
   • Ask who was supposed to request approval.
   • Emergency rules depend on your plan and situation.
2. 02

   Not medically necessary

   The plan decided the care was not needed under its own clinical rules. Medical necessity means the plan's rules for deciding whether care is needed.

   What the appeal needs

   • A clinician explains why the care was needed.
   • Records address the plan's stated clinical reason.
   • You request the criteria used for the decision.

   Watch out for

   • A clinician's opinion may not address the plan's exact criteria.
   • Ask for the records and clinical criteria used.
   • External review may be available for medical judgment denials.
3. 03

   Out of network

   A network is the group of providers that has an agreement with the plan. Care from outside that group may be paid at a lower level or denied, depending on the plan and circumstances.

   What the appeal needs

   • The plan identifies the provider as outside its network.
   • The directory listed the provider differently.
   • No suitable in-network option was available.

   Watch out for

   • Check each provider involved, not only the main facility.
   • Ask which network rule applied on the service date.
   • Emergency and other exceptions depend on the plan and situation.
4. 04

   Not covered by the plan

   The plan says the service is excluded or limited by its written terms. An exclusion is care the plan leaves out, while a limit restricts when or how much it covers.

   What the appeal needs

   • The letter names an exclusion or coverage limit.
   • The plan document may describe the benefit differently.
   • The service may have been placed under the wrong benefit category.

   Watch out for

   • Ask for the exact plan provision and section used.
   • Ask whether another covered benefit category applies.
   • Coverage depends on the plan terms and applicable rules.
5. 05

   A coding or paperwork error

   A claim uses codes and details to describe the care. A wrong code, missing form, typo, or missing detail can stop processing and may require a corrected claim.

   What the appeal needs

   • A code, date, name, or service detail is wrong.
   • The office can provide a missing record or form.
   • The plan says it needs more information.

   Watch out for

   • Ask whether the plan wants a correction, an appeal, or both.
   • Compare the EOB with the office's records.
   • Keep copies and proof of every submission.

Rules to know

Time to file an internal appeal

HealthCare.gov says you must file an internal appeal within 180 days (6 months) of receiving the notice that your claim was denied. In an urgent health situation you can ask for an external review at the same time as your internal appeal.

Internal appeals | HealthCare.govchecked November 3, 2026

How fast the plan must tell you it denied a claim

HealthCare.gov says your insurer must notify you in writing, and explain why, within 15 days if you are seeking prior authorization for a treatment, within 30 days for medical services already received, and within 72 hours in urgent care cases.

Internal appeals | HealthCare.govchecked November 3, 2026

How fast the plan must decide your appeal

HealthCare.gov says an internal appeal must be completed within 30 days if it is for a service you have not received yet, and within 60 days if it is for a service you already received. An urgent appeal needs a decision as quickly as your medical condition requires, and within 4 business days after the request is received.

Internal appeals | HealthCare.govchecked November 3, 2026

Time to ask for an external review

HealthCare.gov says you must file a written request for an external review within 4 months after the date you receive the notice or final determination from your insurer that your claim has been denied.

External Review | HealthCare.govchecked November 3, 2026

Original Medicare has its own appeal levels

Original Medicare has 5 levels of appeal. The first level is a Redetermination: file it by the date in your Medicare Summary Notice (MSN). If you miss the date, you may still file if you can show good cause.

Appeals in Original Medicare | Medicarechecked November 3, 2026

How to appeal, step by step

1. Read the denial letter or EOB for the exact reason, instructions, and deadline in your letter.
2. Ask the plan for the documents, plan terms, and clinical criteria used for the decision.
3. Ask the doctor's office for records or a corrected claim addressing the stated reason.
4. File an internal appeal, meaning a request for the plan to review its decision again.
5. If that appeal is denied, ask whether external review is available, meaning review by an independent reviewer outside the plan.
6. Medicare and employer plans each have their own appeal steps, so follow the applicable notice and plan documents.

Sample appeal letter