Documentation requirements become more complicated when one parent or guardian is traveling alone with a minor. In general, besides your passport, you should bring written consent from the child’s biological parent(s) along with the child’s birth certificate. Many countries require that the consent document be witnessed and notarized. Several websites let you download or print free parental consent forms.
Be aware that specific rules about documentation can differ substantially from country to country. You should check the US State Department International Travel website for information about requirements for your destination country. Find your destination country, then the tab for "Entry, Exit, & Visa Requirements," then scroll down to "Travel with Minors."
These excerpts regarding Canada, Mexico and the Bahamas (a popular port of call on Caribbean cruises) are good points of reference and demonstrate how varied the rules can be:
“If you plan to travel to Canada with a minor who is not your own child or for whom you do not have full legal custody, CBSA may require you to present a notarized affidavit of consent from the minor’s parents. Please refer to the CBSA website for more details. There is no specific form for this document, but it should include dates of travel, parents’ names, and photocopies of their state-issued IDs.”
“Effective January 2, 2014, under Mexican law travel by minors (under 18 years of age) must show proof of parental/guardian permission to exit Mexico. This regulation applies if the minor is traveling by air or sea; traveling alone or with a third party of legal age (grandparent, uncle/aunt, school group, etc.); and using Mexican documents (birth certificate, passport, temporary or permanent Mexican residency).
"The minor is required to present a notarized document showing the consent to travel from both parents (or those with parental authority or legal guardianship), in addition to a passport, in order to leave Mexico. The document should be in Spanish; an English version must be accompanied by a Spanish translation. The document must be notarized or apostilled. The minor should carry the original letter (not a facsimile or scanned copy) as well as proof of the parent/child relationship (birth certificate or court document such as a custody decree, plus photocopies of both parents’ government-issued identification).
"According to INM, this regulation does NOT apply to a minor traveling with one parent or legal guardian, i.e., a consent letter from the missing parent is NOT required. In addition, the regulation is not intended to apply to dual national minors (Mexican plus another nationality) if the minor is departing Mexico using the passport of the other nationality. However, if the minor is departing Mexico using the Mexican passport, the regulation does apply. The Embassy nevertheless recommends that dual nationals travel prepared with a consent letter from both parents.
"The U.S. Embassy in Mexico City has received numerous reports of U.S. citizens being required to provide notarized consent forms for circumstances falling outside of the categories listed above, and/or being asked for such permission at land border crossings. Therefore, the Embassy recommends all minors traveling without both parents carry a notarized consent letter at all times in the event airline or Mexican immigration representatives request one.
"Travelers should contact the Mexican Embassy, the nearest Mexican consulate, or INM for more information.”
“Minors traveling unaccompanied or accompanied by a guardian or chaperone: What is required to enter The Bahamas may vary greatly from what is required to re-enter the country of origin. In general, a child under 16 years of age may travel into the Bahamas merely with proof of citizenship. Proof of citizenship can be a raised seal birth certificate and preferably a government-issued photo ID if on a closed-loop cruise or a U.S. passport if entering by air or private vessel.
"The Bahamas requires compliance with regulations to divert child abduction. Any child traveling without one of the parents listed upon the birth certificate must have a letter from the absent parent granting permission for the child to travel. This should be sworn before a notary public and signed by the absent parent(s). If the parent is deceased, a certified death certificate may be necessary.
"It is advisable to have the minor carry a written notarized consent letter from both parents (if both are listed on the child’s certificate of birth) before sending your child to travel as a minor with a guardian or chaperone.”
Are you flying with kids within the US? You should know about REAL ID, the new identification required for domestic air travel.