Appeal an Aetna Denied Claim — Attorney-Drafted Letter Templates

By Tatiana Kadetskaya, Insurance Attorney

Aetna denies approximately 22% of health insurance claims — well above the industry average. If your claim is in that pile, you are not powerless. You have the legal right to appeal, and when appeals are properly documented and structured, the majority are overturned.

The key is knowing Aetna's specific process, citing the right internal documents, and submitting an appeal letter that speaks the language their reviewers are trained to respond to. This page gives you everything you need.

Aetna Appeal Deadlines — Act Immediately

Commercial plans (employer and individual): You have 180 days from the date of the denial letter to file your internal appeal. Aetna strictly enforces this deadline — appeals received even one day late are rejected without review.

Medicare Advantage plans: The deadline is 65 days from the denial date. This is significantly shorter than commercial plans. If you are on a Medicare Advantage plan, begin immediately.

Expedited appeals: If waiting for a standard review could seriously harm your health, request an expedited appeal. Aetna must respond within 72 hours (36 hours for two-level appeal plans). Call the number on your member ID card and ask for expedited review.

Aetna's response timelines once they receive your appeal: 30 days for pre-service appeals (treatment not yet received), 60 days for post-service appeals (treatment already received).

Where to Send Your Aetna Appeal

By mail: Aetna Inc. P.O. Box 14463 Lexington, KY 40512-4463

Important: Always use the address printed on your denial letter or EOB — Aetna routes appeals differently by plan type and state, and the correct address for your specific plan may differ. The address above is the general national appeals address. If your denial letter lists a different address, use that one.

By phone: Call the Member Services number on the back of your insurance card.

Online: Through your Aetna member account at aetna.com.

Send your appeal by multiple channels — certified mail and online portal — and keep proof of every submission.

The Document That Determines Everything: Aetna's Clinical Policy Bulletins

Aetna uses internal documents called Clinical Policy Bulletins (CPBs) to define what it considers medically necessary. Every medical necessity denial is based on a specific CPB. If you do not know which CPB Aetna applied to your claim, you are arguing blind.

You are legally entitled to see this document. Call Aetna Member Services and ask for "the Clinical Policy Bulletin used to evaluate my claim for [treatment name]." Once you have it, your appeal can directly demonstrate that your treatment meets the CPB's own criteria — which is the most powerful argument you can make.

Common Aetna Denial Types and How to Fight Each One

"Not medically necessary" — Request the specific CPB. Get your physician to write a detailed letter showing your treatment meets the CPB criteria point by point. Include clinical guidelines from relevant specialty societies.

👉 Medical Necessity Appeal Letter Template — Attorney-Drafted

"Out-of-network provider" — Document that no in-network alternative was reasonably available, that care was urgent, or that the No Surprises Act applies. Request Aetna's network adequacy standards for your area.

👉 Out-of-Network Denial Appeal Letter Template — Attorney-Drafted

"Lack of prior authorization" — Establish the clinical urgency of the care, document any communication with Aetna about authorization, and cite emergency care protections if applicable.

👉 Prior Authorization Denial Appeal Letter Template — Attorney-Drafted

"Not covered / policy exclusion" — Request your full plan document and the specific exclusion language Aetna is applying. Challenge ambiguous exclusion language — courts consistently interpret policy ambiguity in the member's favor.

👉 Policy Exclusion / Not Covered Appeal Letter Template — Attorney-Drafted

"Experimental or investigational" — Present peer-reviewed clinical studies, CPB analysis, and your physician's clinical rationale showing the treatment is accepted medical practice. Aetna's CPBs for experimental treatments are frequently outdated.

👉 Experimental Treatment Appeal Letter Template — Attorney-Drafted

Denial codes PR-1 or CO-167 — Request a full deductible calculation statement (PR-1) or verify the diagnosis and procedure codes with your provider's billing office (CO-167) before filing.

👉 PR-1 Deductible Appeal Letter — Attorney-Drafted 👉 CO-167 Mismatch Appeal Letter — Attorney-Drafted

Request a Peer-to-Peer Review First

Before filing your formal written appeal, ask your physician to request a peer-to-peer review with Aetna's medical director. This is a direct conversation between your doctor and the Aetna physician who reviewed your claim — and many denials are reversed at this stage before a formal appeal is even needed.

To request one: include a note with your appeal request form asking for a peer-to-peer review, or call Aetna Member Services. Note: peer-to-peer review is not available for Aetna's Level of Severity inpatient payment determinations under the 2026 policy — those require a separate severity discussion process.

If Your Aetna Internal Appeal Is Denied

You have the right to request external review by an independent organization with no relationship to Aetna. Their decision is legally binding — Aetna must comply. External review is available when the denial involves medical necessity or experimental/investigational status and your financial responsibility exceeds $500. You typically have four months from the final internal denial to request it.

You may also file a complaint with your state's Department of Insurance at any stage.

Start Your Aetna Appeal Today

👉 Browse all attorney-drafted appeal letter templates → 👉 Not sure which template fits your denial? Find out in 2 minutes → 👉 Download the free Appeal Guide →