How do I appeal a denied claim with Aetna, and what is the deadline?

There are two doors here, and the page names only one. The Aetna member page gives three ways to file a complaint [1]. You can file a non-Medicare complaint online [1]. You can print a non-Medicare complaint form and mail or fax it [1]. Or you can review the Medicare complaint process [1]. That is the complaint route. It is not the appeal of the claim decision. The same page says your state insurance office can help you if you do not agree with a decision made by your health plan, or if you need to appeal a decision [1]. These sources do not give the appeal address for your plan. Take that from your denial letter.

The deadline is the part that is hardest to get wrong. For a job-based group health plan, the federal rule gives you at least 180 days to appeal [2]. The 180 days run from when you got the notice [2]. HealthCare.gov gives the same number for a Marketplace plan [3]. Your own denial letter states the address and the deadline for your plan. Copy those two lines before you write.

After a final denial there is a review outside the plan. The numbers I can source are the Marketplace ones. You must ask for an external review within 4 months of that final notice [4]. Your insurer must by law accept the external reviewer's decision [4]. Is your plan through a job? Then ask the plan for its own external review notice. These sources do not set that deadline for you. Send the appeal so the date is provable, and keep a copy of everything.

Open the Aetna complaints, grievances and appeals page. Read the heading 3 ways to file a complaint, which is about complaints [1]. Then open the HealthCare.gov internal appeals page and read the 180-day line [3]. Now compare both with the deadline printed on your own denial letter. Which appeal address your plan uses: "Don't know yet" here. Which external review applies to a job-based plan: "Don't know yet" too.