The short answer
For a flight inside the U.S., your kids need almost nothing — the TSA does not require travelers under 18 to show ID. The moment you cross a border, the rules flip hard: every child needs their own passport, a child's passport takes weeks to get, applying usually requires both parents in person, and if only one parent is traveling, some countries want a notarized consent letter. None of that is hard — but every piece has a lead time, so the only real mistake is starting late.
Work through the documents in the order below, matched to the kind of trip you're taking.
Key takeaways
- Domestic flights: no ID for under-18s. The TSA does not require children under 18 to show identification when flying within the United States; the accompanying adult shows ID for the family.
- Any international trip: every child needs their own passport. There's no "add the baby to a parent's passport" anymore — newborns included.
- Child passports take real time. Routine processing is 4–6 weeks and expedited is 2–3 weeks, plus mailing on each end. Child passports are also valid for only 5 years, not 10.
- Both parents usually have to apply in person. If one can't be there, you file a notarized Form DS-3053 consent — and it's only valid for 90 days after it's signed.
- One parent traveling abroad? Carry a consent letter. U.S. Customs and Border Protection notes some countries require a signed, sometimes notarized, letter from the absent parent.
Step 1: Figure out which trip you're taking
The entire document list comes down to one question — are you leaving the country or not? It's the same triage logic as getting kids through airport security: handle the requirement that actually applies and ignore the rest.
| Trip type | What each child needs |
|---|---|
| Domestic flight (within U.S.) | Nothing required for under-18s. The accompanying adult needs a REAL ID-compliant license or passport. |
| International by air | The child's own valid passport book. Some destinations also need a visa or proof of onward travel. |
| Cruise / land or sea to Mexico, Canada, Caribbean | A passport book is safest. Closed-loop cruises have narrower exceptions — confirm with the cruise line before you rely on a birth certificate. |
| One parent traveling internationally with the kids | All of the above, plus a notarized consent letter from the non-traveling parent. |
Step 2: Domestic flights are the easy case
If you're flying somewhere in the U.S., relax — this is the one part of family travel paperwork that's genuinely simple. The TSA does not require children under 18 to provide identification on domestic flights. One adult in the group shows a REAL ID-compliant ID and the kids walk through.
The one wrinkle: an unaccompanied minor flying alone with TSA PreCheck needs an acceptable ID to get PreCheck screening, and individual airlines set their own rules for kids flying solo. So check with the airline, not the TSA, for an unaccompanied-minor flight — the airline's policy is the one that bites.
The other wrinkle is a lap infant. The TSA asks nothing, but airlines can ask you to prove a lap child is under 2. Southwest, for example, says its staff may request proof of age and accepts only an original or photocopied government document, such as a passport or birth certificate; screenshots and immunization records don't count, and without proof you buy the child a seat. Pack a copy of the birth certificate for any lap-infant flight.
Step 3: International means a passport for every child
There is no shortcut here. Every U.S. citizen, including a newborn, needs their own passport book to fly internationally, even on the shortest international flights from LAX. The piece parents underestimate is lead time:
| Service | Processing time | Notes |
|---|---|---|
| Routine | 4–6 weeks | Plus mailing time on both ends — budget closer to two months. |
| Expedited (extra fee) | 2–3 weeks | Faster, but still not same-week. |
| Validity | 5 years | Child passports last half as long as the 10-year adult version — check the expiry before every trip. |
And check the destination's own rule: many countries require a passport to be valid for 3–6 months beyond your travel dates, so a passport that expires "after" your trip can still get a child turned away at check-in; Europe also has new EES border rules for families, and our ETIAS checker sorts out whether your family needs ETIAS, EES or a Schengen visa.
Step 4: The two-parent rule (and the form that saves you)
This is the requirement that catches families off guard. To apply for a passport for a child under 16 using Form DS-11, both parents or guardians must appear in person with the child. If one parent can't be there, you submit Form DS-3053, Statement of Consent — notarized, with a photocopy of that parent's ID.
Watch the clock: a notarized DS-3053 (and other notarized statements) must be submitted within 90 days of being signed. Notarize it too early and you'll be redoing it.
If you are the child's only parent or have sole legal custody, you apply alone but bring evidence of that — a birth certificate listing one parent, a court custody order, or a death certificate. Plan for two fees, too: the application fee to the State Department plus an acceptance facility fee where you file.
Step 5: One parent traveling? Pack a consent letter
Here's the document almost nobody knows about until an agent asks for it. U.S. Customs and Border Protection notes that some countries require a child arriving or leaving without both parents to carry a letter of consent — in some cases notarized — from the absent parent or guardian.
It costs nothing to be ready. Carry a short signed letter that includes:
- The child's full name and date of birth, and the traveling parent's name.
- A clear statement that the non-traveling parent consents to the trip, with the dates and destination.
- The absent parent's contact information and signature — notarized if you have any doubt.
This matters most for divorced, separated, or single-parent families, but a notarized letter is cheap insurance for anyone where one parent stays home. The same letter helps if a grandparent or other adult is taking the kids abroad without you.
What most parents get wrong
The myth isn't that the paperwork is complicated — it's that you can sort it out close to the trip. You can't. A child passport with both parents present is a slow, scheduled errand, not a same-week task, and a missing consent letter is something you only discover at a foreign border with no way to fix it. The research-backed move is boring: open the passports the moment a trip is even possible, and treat the consent letter as default packing for any one-parent international trip. None of these documents is hard — they just refuse to be rushed.
Sources
- TSA — Identification (children under 18 not required to show ID on domestic flights)
- U.S. Department of State — Apply for a Child's Passport Under 16 (both parents in person; 5-year validity; DS-3053)
- U.S. Department of State — Passport Processing Times (routine 4–6 weeks, expedited 2–3 weeks)
- Southwest Airlines — Traveling with an infant (proof of age for a lap child: passport, birth certificate or government photo ID)
- U.S. Customs and Border Protection — Minor children traveling without both parents (consent letter)
If Spain is on your shortlist, pair this checklist with our Madrid with kids guide so documents, late dinners, and metro logistics are planned together.
