Yes, American Airlines AAdvantage miles expire after 24 months of account inactivity, but there are several easy ways to prevent this in 2026. "Activity" is defined as either earning or redeeming at least one mile within that 2-year window. If you use a co-branded AAdvantage credit card (like those from Citi or Barclays) for even a single purchase, your miles will not expire as long as your card account remains open. Additionally, miles do not expire for AAdvantage members who are under the age of 21. For everyone else, simple actions like making a purchase through the AAdvantage eShopping portal, dining at a partner restaurant, or donating a small number of miles to charity will reset your 24-month clock. If your miles have already expired, American Airlines allows you to "reinstate" up to 500,000 miles for a fee, provided they expired within the last 24 months.