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How to appeal an insurance denial letter

Find three things in your letter: the reason they gave, the rule or policy section they cited, and your appeal deadline. Your appeal should answer that exact reason, with records attached. If your insurer still says no, most health plans must then let you ask for an independent external review.

Not Final does that reading for you: upload the letter and get what they decided and why, your deadline, the rule they cited, and a drafted appeal letter with a checklist of what to attach, for $0.99 per letter. No account. Unpaid letters are deleted within 2 hours.

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How insurance denials work

A denial is the insurer's first decision, not the last one. For health plans, the insurer has to tell you in writing why it denied the claim. Common reasons include:

• The service is "not medically necessary."
• The treatment is "experimental" or "investigational."
• The provider or facility is out of network.
• The benefit isn't covered by your plan, or prior authorization wasn't on file.
• A coding, billing or paperwork problem, or missing information.
• Eligibility: the plan says you weren't enrolled or covered on that date.

Many denials happen because the insurer didn't have the right records. That's why an appeal that answers the stated reason with evidence can work.

Step 1: Read the letter (or Explanation of Benefits) closely

• The reason: the exact words they used for why it was denied.
• The rule: the policy section, clinical guideline or plan term they cited. If none is cited, you can ask for it.
• The deadline: how long you have to appeal and where to send it (mail, fax or online portal).
• Your details: claim number, member ID, date of service, provider name.

Step 2: File an internal appeal with the insurer

An internal appeal asks the insurer to take a second look. Use their appeal form if they have one, or write a letter with your name, claim number and member ID, and send any extra information you want considered, such as a letter from your doctor.

• Deadline: for most health plans covered by federal rules, you have 180 days (6 months) from when you got the denial notice. Always go by the deadline in your own letter or plan documents if it's different.
• How long it takes: the insurer must decide within 30 days for care you haven't had yet and 60 days for care you already got.
• Urgent care: if waiting could seriously harm your health, ask for an expedited (urgent) appeal. You can request an external review at the same time.
• Free help: your state's Consumer Assistance Program or Department of Insurance can help, and in many cases can file the appeal for you.

Step 3: Ask for an external review if they still say no

An external review sends your case to an independent reviewer outside the insurance company. For health plans, the insurer has to accept the reviewer's decision.

• Deadline: file a written request within 4 months of the insurer's final denial.
• How long it takes: no later than 45 days for a standard review, and 72 hours or less for an expedited one.
• Cost: free under the federal (HHS) process; state or contracted reviews can charge at most $25.
• Where to file: your final denial letter must tell you how to ask for external review and who handles it.

Different rules can apply to Medicare, Medicaid, some employer plans, older "grandfathered" plans, and non-health insurance like auto, home, life or disability policies. When in doubt, follow the appeal instructions in your letter and your plan or policy documents, and call the number on the letter to confirm your deadline.

What to include in your appeal

• A copy of the denial letter or Explanation of Benefits.
• A letter from your doctor explaining why the care was needed, tied to your diagnosis.
• Relevant medical records, test results and notes.
• The plan language that supports coverage, if you can find it.
• Proof of anything the insurer said was missing (prior authorization, referral, corrected billing codes).
• A request for copies of the documents, guidelines and criteria they used to deny you.
• Notes from phone calls: date, time, name and what was said.

Keep your originals, send copies, and keep proof of when you sent it (certified mail receipt, fax confirmation or portal screenshot).

Sample insurance appeal letter structure

This is an outline with made-up details. Replace everything in [brackets] and stick to facts you can back up.

[Your name]
[Address] · [Phone] · [Email]
[Date]

[Insurance company name], Appeals Department
[Address or fax number from your denial letter]

Re: Appeal of claim denial
Member: [Name] · Member ID: [ID] · Claim number: [Number]
Date of service: [Date] · Provider: [Doctor or facility]

To whom it may concern:

I am requesting an internal appeal of your decision dated [date of
denial letter] denying coverage for [service or treatment]. Your letter
says the claim was denied because [quote their reason], citing
[policy section or guideline they named].

I disagree for these reasons:
1. [Answer their exact reason. Example: My doctor's attached letter
   explains why this treatment is medically necessary for my
   diagnosis of [condition].]
2. [Point to plan language, records, or corrected information.]
3. [Anything they said was missing, and where it is now attached.]

Please reconsider and approve coverage for this claim. I also request
copies of all documents, records, and criteria used to make this
decision.

Enclosed:
- Copy of the denial letter
- Letter of medical necessity from [doctor], dated [date]
- [Medical records / test results]
- [Other supporting documents]

Sincerely,
[Signature]
[Printed name]

Your options, honestly compared

Option	Cost	Good for
Write it yourself using this guide and HealthCare.gov	Free	Anyone with time to read the letter and plan documents closely.
Your state's Consumer Assistance Program or Department of Insurance	Free	Real people who can help, and in many cases file the appeal for you.
Free health-insurance appeal tools (for example Fight Health Insurance or Counterforce Health)	Free	Health insurance claim denials.
A lawyer or patient advocate	Varies	Large bills, complex cases, or after an external review is denied.
Not Final	$0.99 per letter	A fast plain-English read of any denial letter (insurance, unemployment, financial aid, disability, permits, warranties) plus a drafted appeal and checklist. No account, no questionnaire, and your letter is deleted within 24 hours.

How Not Final helps

Upload a PDF or photo of your denial letter (or paste the text). After you pay $0.99, in about 30 seconds you get:

• What they decided and why, in plain English.
• Your appeal deadline, with the calendar date worked out when the letter gives a number of days.
• The rule or policy they cited, and whether their reason seems to match it.
• Evidence that usually helps in this kind of appeal.
• A drafted appeal letter using the names, numbers and dates from your letter, ready for you to edit.
• A checklist of what to attach.

Your results stay at a private link for 24 hours, then they're permanently deleted. More questions · Privacy

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Not legal advice. This guide is general information about common health insurance appeal rules, not legal advice, and no appeal outcome is guaranteed. Your plan, your state and your type of insurance may have different rules and deadlines. Confirm everything with your insurer, and consider a lawyer, legal aid office or your state's consumer help office.

Sources: HealthCare.gov, Internal appeals and External review. Last reviewed October 17, 2026.