Insurers still run on fax more than almost any other industry. Appeals, claim documents, prior authorizations, and medical records move by fax every day, and many insurers list fax as a standard way to submit a written appeal. The hard part is not sending the fax. It is sending it to the right one of the dozens of lines an insurer operates.

This guide explains how to fax documents to an insurance company: where to find the right number on your own paperwork, how insurers split their fax lines, and verified appeals fax numbers for two of the largest Medicare plan providers as worked examples.

  • Your paperwork has the right number. EOBs, denial letters, and claim letters are the best source.
  • Insurers split fax lines by request type, plan, and urgency.
  • Verified numbers from Aetna and UnitedHealthcare official pages

Table of Contents

Why insurers have so many fax numbers

A large insurer is really many operations under one name. Fax lines are typically split by:

  • Request type: claims, appeals, grievances (complaints), prior authorization, medical records
  • Plan type: employer plans, individual plans, Medicare Advantage, Part D drug plans, Medicaid plans
  • Urgency: standard versus expedited (fast) review, often on separate lines
  • State or region: some plans route by where you live

Aetna's own Medicare appeals page, for example, asks members to choose their state, county, and plan to get the right expedited phone and fax number. An appeal faxed to a claims line, or to a different plan's line, can sit unprocessed while your deadline runs.

Where to find the right fax number

Look in this order:

  1. The denial letter. If you are appealing, the denial notice normally explains how to appeal, the deadline, and where to send it.
  2. Your explanation of benefits (EOB). The EOB identifies the claim, shows what was denied, and often lists contact details for questions or appeals.
  3. Your plan documents. Member handbooks and, for Medicare plans, the Evidence of Coverage list appeals contacts. UnitedHealthcare tells Medicare Advantage members to fax written requests to the number in their Evidence of Coverage.
  4. The insurer's official website. Look for an "Appeals" or "Forms" page for your plan type, on the insurer's own domain.
  5. The member services number on your ID card. Ask for the fax number for your specific request type.

For providers, the insurer's provider portal is usually the authoritative source for prior authorization and claims fax numbers. Our prior authorization guide covers that workflow.

Verified appeals fax numbers (examples)

These numbers come from the insurers' official appeals pages. They apply to the plan types listed only. Employer, individual, and Medicaid plans from the same insurers use different numbers.

Verified October 2026:

Insurer and plan type Request Fax number
Aetna Medicare Advantage (Part C: HMO, PPO, HMO-POS) Medical authorization and claim appeals 1-724-741-4953
Aetna Medicare Advantage (Part C) Expedited appeals (confirm for your plan) 1-724-741-4958
Aetna Medicare Advantage with drug coverage (MAPD) Part D redeterminations 1-724-741-4954
Aetna Medicare Prescription Drug Plan (PDP) Appeals and coverage determinations 1-855-633-7673
UnitedHealthcare Medicare Part D Appeals 1-866-308-6294
UnitedHealthcare Medicare Part D Coverage determinations (Optum Rx Prior Authorization Department) 1-844-403-1028

Notes:

  • Aetna asks members to select their state, county, and plan for the correct expedited number, so treat the expedited line above as a starting point and confirm it.
  • UnitedHealthcare does not list a separate expedited fax for Part D appeals; it asks members to call for an expedited appeal.
  • UnitedHealthcare Medicare Advantage (medical, not drug) appeals numbers vary by plan; UHC directs members to the fax number in their Evidence of Coverage.

Faxing a health insurance appeal

An appeal is an argument, so the order and completeness of what you send matters.

  1. Check the deadline on the denial notice. UnitedHealthcare, for example, allows 65 calendar days from the date of the notice for Medicare Advantage appeals, and 65 days from an unfavourable Part D determination.
  2. Write a short appeal letter. Identify the claim or service, say that you are appealing the denial, and explain why you disagree. Reference the reason given in the denial letter.
  3. Attach the denial notice or EOB so the reviewer can see exactly what is being appealed.
  4. Add supporting evidence: a letter from your doctor, relevant medical records, and anything that answers the specific reason for denial.
  5. Use the plan's appeal form if it has one.
  6. Mark expedited requests clearly and say why. For Medicare Advantage, UnitedHealthcare describes expedited review as being for situations where waiting for a standard decision could seriously jeopardise your life, health, or ability to regain maximum function, with a decision no later than 72 hours.
  7. Put your name, member ID, and claim number on every page, then fax and keep the confirmation.

You do not need a fax machine. You can send a fax online from a browser for a one-time payment, with no subscription and no account, and receive the delivery confirmation by email.

For Original Medicare (not Medicare Advantage), appeals go to a regional contractor rather than an insurer; see how to fax Medicare.

Claims, prior authorization, and auto insurance

Health claims. Most health claims are filed electronically by the provider. Members fax documents mainly when the insurer asks for more information, or when submitting an out-of-network claim with an itemised bill. The insurer's claim form or letter will say where to send it.

Prior authorization. This is usually a provider task, submitted through the payer's portal or to a dedicated authorization fax line. See our prior authorization guide.

Auto and home insurance. Property and casualty claims are usually handled by an adjuster assigned to your claim. If the insurer accepts documents by fax, the number will be on your claim acknowledgement letter or available from the adjuster. Ask for it, and put your claim number on every page. Avoid general corporate fax numbers found online; they rarely route to your claim.

Privacy when faxing insurance documents

Appeals and claims often include medical records, diagnoses, and policy details. HHS guidance on health information notes that confirming a fax number with the recipient is a reasonable safeguard when faxing to a number you do not use regularly. Taking the number from your own insurer's letter or website does the same job.

Faxio stores uploaded documents encrypted and uses them only to render and transmit your fax, as described in our privacy policy.

Faxing an insurer comes down to sending the right documents to the line for your plan and request type, with your claim number on every page, and keeping your confirmation. When the number comes from your own paperwork, fax remains one of the fastest ways to get an appeal on record.

Fax your insurance documents now →

Frequently asked questions

Where do I find my insurance company's fax number?

Start with the paperwork about your claim: the denial letter, explanation of benefits (EOB), or claim letter. For appeals, health plans also list fax numbers in the member handbook or Evidence of Coverage and on their website's appeals page. Use the number for your specific plan and request type.

Can I fax a health insurance appeal?

Usually, yes. Many health plans accept written appeals by fax, mail, or online. Aetna, for example, lists 1-724-741-4953 for Medicare Advantage Part C appeals, and UnitedHealthcare lists 1-866-308-6294 for Medicare Part D appeals.

How long do I have to file an insurance appeal?

It depends on the plan and the type of coverage, and the deadline is stated on the denial notice. UnitedHealthcare, for example, gives members 65 days from the date of an unfavourable Part D determination to appeal.

Can I fax an auto insurance claim?

Auto insurers usually handle claims through an adjuster assigned to your claim, and the fax number, if they use one, is on the claim letter or comes from the adjuster. Ask for it directly and always include your claim number.

Is it safe to fax medical records to my insurer?

Fax is widely used for health information, and HHS guidance treats confirming the destination number as a reasonable safeguard. The main risk is a wrong number, so check every digit against your insurer's letter or official website.

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