How to Appeal a Denied Health Insurance Claim
Published July 10, 2026 · 8 min read
A denial letter feels final, but it is really just the insurer’s opening position. You have the right to appeal, the deadlines and steps are set out by law, and a large share of denials come down to fixable technicalities rather than a true no. Knowing how to push back is one of the most valuable money skills there is. This is the version Steward would walk you through.
First, find out why it was denied
Every denial comes with a reason, printed on your Explanation of Benefits or a separate denial letter as a short code and phrase. You cannot appeal what you do not understand, so start here. If the reason is vague, call the number on your card and ask them to explain the specific denial code in plain language, then write down what they say and who said it.
The common reasons, and what they really mean
- Missing or incorrect information. A wrong code, a typo in a date, or a detail the provider left off. Usually the easiest to fix, often with a corrected resubmission.
- Prior authorization not obtained. The plan required approval in advance and did not get it. The provider can sometimes request it after the fact.
- Not medically necessary. The insurer disagrees that the care was needed. This is where a letter of medical necessity from your provider matters most.
- Out-of-network. The provider was outside the plan’s network. Check whether the No Surprises Act applies, or ask for a network exception.
- Not a covered benefit. A true coverage exclusion. Harder to overturn, but worth confirming against your actual plan documents, which sometimes say otherwise.
Step 1: File the internal appeal
Your first move is to ask the insurer to reconsider. This is the internal appeal. You generally have 180 days from the denial date, and the instructions are on the denial notice. Submit it in writing, keep a dated copy, and send it in a way you can track. If your situation is urgent, request an expedited appeal, which must be decided much faster.
Step 2: Write a clear, specific appeal
An appeal is not a complaint. It is a short, factual case. Include:
- Your name, member ID, and the claim number.
- The exact denial reason and code from the EOB.
- A brief explanation of why the service should be covered.
- Supporting evidence: a letter of medical necessity from your provider, relevant medical records, and the page of your plan documents that supports coverage.
Ask your provider’s office to help. They deal with denials constantly and can often supply the exact codes and notes that turn a no into a yes.
Step 3: If they still deny it, request an external review
If the internal appeal fails, you usually have the right to an external review by an independent party who does not work for the insurer. Their decision is binding on the plan. This step overturns many stubborn denials, and it is the one most people never reach. The denial notice will explain how to request it and the deadline, which is often four months from the final internal denial.
Keep a paper trail
Throughout, write down every call: the date, the name of the person, and what they told you. Keep copies of every letter you send and receive. If a dispute drags on, that record is what proves your timeline and keeps the insurer accountable.
The bottom line
A denial is a decision you are allowed to challenge, not a bill you have to accept. Find the reason, answer it directly, and escalate to external review if you have to. The goal is the claim paid and your responsibility corrected before you ever pay out of pocket. That is the same fight Steward takes on for you: it reads the denial, matches it against your plan, and drafts the appeal for your approval.
This guide is general information, not legal or medical advice. Deadlines and rights can vary by plan and change over time; confirm the specifics that apply to your situation on your own denial notice and plan documents.
Frequently asked questions
What does a denied claim mean?
A denied claim means your insurer declined to pay for a service, in full or in part. It does not always mean the service was not covered. Denials are often the result of a coding error, missing information, a missed prior authorization, or a provider treated as out-of-network. The reason is listed on your Explanation of Benefits with a code, and many denials can be reversed on appeal.
How long do I have to appeal a denial?
For most plans you have 180 days from the date on the denial notice to file an internal appeal. The exact deadline is printed on your Explanation of Benefits or denial letter. Do not wait, because missing the window can end your options. If your health is at urgent risk, you can request an expedited appeal that is decided far faster.
What is the difference between an internal appeal and an external review?
An internal appeal asks the insurer to reconsider its own decision. If they still deny it, you generally have the right to an external review, where an independent third party who does not work for the insurer makes the final call. The external reviewer’s decision is binding on the plan. Most people stop at the first no, but the external review is where many hard denials are overturned.
Do appeals actually work?
Often, yes, especially when the denial was a technical or coding issue rather than a true coverage exclusion. A clear appeal that names the denial reason, points to your plan documents, and includes supporting notes from your provider has a real chance. The insurer is required to give you a written decision, so a well-documented appeal is hard to ignore.
What should an appeal letter include?
Include your name, member ID, and claim number; the exact denial reason and code from the EOB; a short, factual explanation of why the service should be covered; and any supporting evidence, such as a letter of medical necessity from your provider or the relevant page of your plan’s coverage documents. Keep it calm and specific, and keep a dated copy.
Can I appeal a claim that was denied as out-of-network?
Yes. If the care was an emergency, or an out-of-network provider treated you at an in-network facility, the No Surprises Act may mean it should have been processed at your in-network rate. Point to that in your appeal. Even outside those cases, plans sometimes grant a network exception when no in-network provider was reasonably available.