Children must have their own passport, visa or other international entry documentation required of adults. In addition, certain countries require children leaving that country without both parents and a legal guardian to have a letter of consent, in some cases notarized.

In 2026, a minor cannot fly internationally without a passport for the vast majority of destinations, including virtually all travel involving air travel. For U.S. citizen children, a valid U.S. passport is a mandatory requirement for air travel to any international location, including Canada and Mexico. The only significant "exception" applies to land or sea travel for children under the age of 16 traveling between the United States, Canada, Mexico, Bermuda, or the Caribbean; in these specific cases, an original or certified copy of a birth certificate or a Consular Report of Birth Abroad may be accepted in lieu of a passport. However, even for these routes, a passport is highly recommended to avoid any bureaucratic delays. Additionally, if a minor is traveling with only one parent or a guardian, many countries—and the airlines themselves—require a notarized letter of consent from the non-traveling parent(s) to prevent international parental child abduction. For any international flight, no matter the age of the child (even infants), a passport is the only universally accepted form of identification for boarding.