As of January 25, young persons aged 17 or under may not enter or leave Mexico on their own without a notarized letter/form signed by their parents or legal guardians.
The measure was introduced in 2013 but put on hold for a year by the National Immigration Institute (INM).
The INM says airlines in Mexico are able to download the official forms from the Internet, as well as provide a list of notaries able to provide the service.
Letters elaborated abroad must be legalized, witnessed and translated into Spanish.
The following information is required on the forms: name and nationality of the minor, date of birth, period of travel and the full names, signatures and IDs of the parents or guardians.