If you forgot to input your loyalty number during checkout—or if you weren't even a member at the time of your flight—you can retroactively claim those miles, or request a mileage credit.

Yes, you can generally claim "old" air miles for flights you have already taken through a process known as a Retroactive Claim (or "Retro Claim"), but there are strict time limits. Most major airlines allow you to claim missing miles between 6 and 12 months after the date of your flight. For example, in 2026, Delta and United typically have a 12-month window, while some international carriers like Emirates or Lufthansa may limit it to 6 months. To make a claim, you usually need your ticket number (a 13-digit code starting with the airline's specific prefix) and your boarding pass. You must have been a member of the loyalty program at the time of the flight, although many airlines now allow "new" members to claim miles for flights taken in the 30 to 90 days prior to their enrollment. It is important to note that you can only claim miles for your own travel; you cannot claim miles for a flight taken by a friend or family member. Most claims can be submitted instantly through the airline's mobile app or website, but if the flight was with a "partner" airline, the processing time can take up to several weeks.