For international air travel, yes — every traveler including newborns needs their own passport. For US domestic flights, children under 18 don't need ID when flying with an adult, though the adult does. Children's passports are valid for fewer years than adults'.
International flights: every passenger needs a passport, regardless of age — a lap infant on your ticket still needs their own. Children’s passports are typically valid for five years (versus ten for adults) and must be renewed in person; there’s no auto-renewal for minors.
Some destinations also want the same six-month validity and, for children traveling with one parent or without both, may ask for a consent letter or birth certificate to guard against abduction — check the destination’s rules.
US domestic flights: the TSA does not require ID for anyone under 18 flying with a companion. The accompanying adult needs a REAL ID-compliant license or passport. Airlines may have their own age-proof rules for lap infants (often a birth certificate), so check when booking.
Apply early — children’s passports can take weeks, and the whole family being ready is easy to overlook.
Related questions
How long does my passport need to be valid to travel?
Many countries require six months' validity beyond your arrival or departure date; the Schengen area requires three months beyond your planned exit and a passport issued within the last ten years. Airlines enforce these rules at check-in. Full answer →
How do I fly with a baby or toddler?
Under-2s can fly on your lap (often free domestically, ~10% of the fare internationally) or in their own seat with a car seat. Request a bassinet on long-haul, board early, feed during takeoff and landing for ear pressure, and pack twice the nappies you think you need in the cabin. Full answer →
Can my child fly alone as an unaccompanied minor?
Yes — airlines carry unaccompanied minors, usually from age 5, through a paid escort program with an extra fee each way. The child is checked in by one named adult and handed to another named adult at the destination. Age rules, fees and whether connections are allowed vary a lot by airline. Full answer →
Airline, airport and government rules change without notice. Treat this as a starting point and confirm with the airline or authority for your specific trip. Request a correction if something is out of date.