Before you book or board an international trip, check the documents that decide whether an airline can let you travel. The most important items are simple: passport expiration, destination entry rules, any visa or electronic travel authorization, and backup copies if something is lost.
The check matters more in 2026 because some travel permissions now happen before the border. The United Kingdom says many visitors, including travelers from the United States, usually need an Electronic Travel Authorisation, or ETA, unless they need a visa or qualify for an exemption. The UK began enforcing the broader ETA requirement on February 25, 2026.
The U.S. State Department also tells travelers to check passport expiration early. Some destinations require a passport to remain valid for at least six months after travel dates, and some airlines may deny boarding if that rule is not met.
Do this first
Check the expiration date on every passport in the group, including children. U.S. passports issued to adults are generally valid for 10 years, while passports issued to children under 16 are valid for 5 years. If the passport is close to expiring, check the destination's rules before buying nonrefundable tickets.
Then check whether the destination requires a visa, ETA, ESTA, eVisa, or another travel authorization. The State Department recommends checking the entry, exit, and visa requirements for the country you plan to visit. Airline rules can also matter because carriers often screen documents before boarding.
If your trip includes the UK
Use the official GOV.UK ETA page, not a look-alike service. GOV.UK says an ETA lets eligible visitors travel to the UK, Jersey, Guernsey, or the Isle of Man for up to six months, costs 20 pounds, and does not guarantee entry. Each traveler needs their own ETA, including babies and children.
Do not assume a connection is exempt. GOV.UK says travelers passing through UK border control during a landside airport transit need an ETA if they are otherwise required to have one. If your itinerary changes from airside to landside, that can change the document check.
Check these details
Make copies of the passport photo page, visas, and travel authorizations. The State Department recommends keeping one set separate from the originals, leaving a set with someone trusted, and taking phone photos of travel documents. Those copies can speed replacement if documents are lost or stolen.
Confirm the name, passport number, issue date, and expiration date used in any travel authorization. If you renew a passport after getting an authorization, the old document number may no longer match. Update trusted-traveler accounts, airline profiles, and cruise or tour records when a passport changes.
Common mistakes
Travelers often check only the expiration date and miss the six-month-validity rule. They also assume a child passport lasts as long as an adult passport, forget that each person needs separate permission, or use a commercial application site that charges more than the official government fee.
The safest routine is to check documents when planning starts, again before final payment, and once more a week before departure. If any rule is unclear, use the official government page for the destination and confirm with the airline before you leave for the airport.
