Mexican laws regarding brining children into Mexico are strict. There have been cases in the past where in custody cases, one spouse might disappear into Mexico taking a child that they were not awarded custody of. The Mexican government has implemented these strict rules to avoid this possibility.
People with children should bring their child's birth certificate.
Single parents, grandparents or guardians traveling with children often need proof or notarized letters from the other parent authorizing travel or a sole custody agreement.
If you are a women traveling with a child, you will definitely want Notarized Permission, in writing, from the father.
If you cannot get consent, then you may be able to arrange for a court order. Also getting a passport issued in the child’s name can help facilitate the border crossing into Mexico.
Almost an Adult!
Applicants, under 18 years old, traveling by themselves, must present a notarized authorization, signed by both parents or legal guardians, granting their permission to get their tourist visa.