(Airlines, however, have their own set of rules about children and IDs, so check beforehand. And passports are always required on international flights.) TSA agents may ask a child how old he or she is. Those 18 and older need a government-issued ID just like everyone else -- and a student ID with a photo won't do.

Yes, TSA knows your age the moment they scan your ID or boarding pass at the security checkpoint. In 2026, the "Secure Flight" system used by the Transportation Security Administration (TSA) automatically links your identity document to the passenger data provided when you booked your flight. This data includes your full name, gender, and date of birth. When the officer scans your passport or Real ID at the Credential Authentication Technology (CAT) machine, your age is displayed on their screen, often highlighted if you fall into specific categories. This is primarily used for security "segmentation." For example, the TSA has different screening rules for children 12 and under and seniors 75 and older, both of whom are generally allowed to leave their shoes on and wear light jackets through the scanner. Even if you are using a digital ID on your smartphone, the encrypted data shared with the TSA includes your birthdate. This information ensures that the correct "risk-based" screening protocol is applied to you, making the process faster for the very young and the elderly while maintaining a high level of security for the general traveling public.