Yes, you can add your Avios (Executive Club) number to a flight booking after it has been made, and even after you have flown. In 2026, for British Airways or partner flights (like Qatar Airways or American Airlines), you can log in to "Manage My Booking" on the airline's website and enter your loyalty number at any time before departure. If you have already completed your flight and forgot to add your number, you can claim missing Avios up to six months after the flight date via the online "Claim Missing Avios" form in your Executive Club account. You will need your flight number and the 13-digit ticket number. New members can even claim points for British Airways flights taken up to three months before they joined the program, making it easy to recover value from past travel.