What documents do I need if my child has a different surname from one parent when traveling through Vietnam?

A parent had the child listed in their own passport, which was accepted at the border, but when booking return tickets via Trip.com the reservation failed because the system flagged identical passport numbers for the mother and child. They had to urgently get the child a separate passport and correct the booking.

A separate new-style child passport was issued in about a week, and an old-style one even faster, so getting a child their own document urgently is feasible on short notice.

One traveler noted it's safer for a child to have their own separate passport rather than just being listed in a parent's passport — some countries won't admit a child who is only listed and lacks an individual document.

If the mother's surname differs from the child's (while the father and child share a surname), border officers may ask questions. Bring the child's birth certificate to prove the family relationship, and consider a notarized parental consent letter from the other parent.

You do not need to replace a child's passport just because the photo no longer matches their current appearance — the passport remains valid until its expiry date. One traveler confirmed successfully using their daughter's passport issued at 4 months old when she was already 10 years old.