Add your Known Traveler Number (KTN) to your United MileagePlus profile and existing reservations. If you have Global Entry, NEXUS or SENTRI, your 9-digit PASS ID is your KTN. It's on the back of your card in the upper-left corner and in your TTP profile.

Yes, you can add your TSA PreCheck Known Traveler Number (KTN) to an existing United Airlines reservation at any time before you check in. The most efficient way to do this is via the United mobile app or the official website. Simply navigate to the "My Trips" or "Manage Reservations" section, locate your current booking, and select "Edit Traveler Information." From there, you can input your KTN into the designated field. If you have already checked in, you may need to "un-check in" to update the information so that the TSA PreCheck indicator appears on your digital boarding pass. Alternatively, you can visit a United kiosk at the airport or speak with a gate agent, though doing it digitally in advance is recommended. It is vital to ensure that the name on your reservation exactly matches the name on your TSA PreCheck account, including any middle names or initials, otherwise, the system will fail to validate your status.