But if you forgot, it's OK. Most airlines, Keyes said, allow travelers to request miles three to 14 days after booking and within 12 months of travel.

Yes, you can generally claim frequent flyer miles for old flights, but there are strict time limits and conditions that vary by airline. In 2026, most major carriers like Delta, United, and American Airlines allow you to request "retroactive credit" for flights taken within the last 6 to 12 months. However, a crucial requirement is that you must have been a member of the loyalty program at the time of the flight, or in some cases, join within 30 days of the flight date. To process the claim, you typically need your 13-digit ticket number and your boarding pass or flight confirmation email. If you flew on a partner airline, the process can take longer (up to 30 days) to verify. It is important to note that you cannot "redeem" miles you never earned; you must first successfully claim the credit to your account before those miles can be spent on future travel. Always keep your digital receipts until the miles appear in your account, as "missing mileage" is one of the most common administrative hurdles in the aviation industry.