TSA does not require children under 18 to provide identification when traveling within the United States. Contact the airline for questions regarding specific ID requirements for travelers under 18.
Children under 18 don't need an ID to fly domestically but do need a passport for international flights.
Is a minor travel consent form required for domestic travel? No, a minor travel consent form is not required for domestic travel within the U.S. However, it is recommended that parents and/or legal guardians carry a notarized letter of consent when traveling with a child.
You don't need any documentation. The only time you would need a birth certificate is if you were flying with them as a lap child. I just flew 3 southwest flights with my four year old and he was only asked what his name was by TSA. Didn't have to show anything.
How do I write a consent letter for my child to travel? List your child's name, birth date/place, and passport details. Provide the parent's/guardian's name, custody information, and passport details. Add contact information for the non-traveling parents/guardians. Detail the child's destination and dates of travel.
There is no documentation requirement for domestic travel in the US for children flying with a parent. I've flown dozens of times with no one saying boo.
Can the Child (Minor) Travel Consent be notarized online? Yes. Online notarization of the Child (Minor) Travel Consent is completely legal and secure. Your documents can be notarized online in minutes through the Notarize Network, starting at $25.
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.
You should obtain a child travel consent letter granting you permission from the absent parent to leave the country with your child (having it notarized is not required, but highly recommended).