To check or change your seat on British Airways in 2026, the most direct method is using the "Manage My Booking" portal on their official website or the BA mobile app. You will need your six-character Booking Reference (e.g., L6Y2P4) and the lead passenger's last name. Once logged in, you can view the live seat map for your specific aircraft. If you have a "Basic" (Hand Baggage Only) fare, you typically have to pay to select a seat before check-in, or wait until the 24-hour check-in window opens to see your randomly allocated seat for free. For 2026 travelers with Executive Club status (Silver or Gold), seat selection is usually free from the time of booking. If you are flying on a codeshare flight (e.g., a BA flight operated by American Airlines), you may need to use the operating airline's app with their specific reference number to view the seat map, as the BA app sometimes has limited "write access" to partner seat configurations.