If the child is not accompanied by both parents, we recommend carrying a consent letter signed by the non-accompanying parent, regardless of the parents' marital status (single, married, common-law, separated, divorced or never married).
Contact A Notary Public: After drafting your letter, reach out to a local notary public or use online services like NotaryCam. Presentation For Verification: Present yourself along with identification documents before signing under oath in front of them.
In the USA, though, unless there's a court order requiring permission from both parents, a child may travel (even to overseas) with either parent/guardian without showing proof of permission from the other parent.
A letter of consent, preferably in English and notarized, from the other parent or signed by both custodial parents. The letter should say: "I acknowledge that my child is traveling outside the country with the name of the adult with my permission."