Even if you have sole legal custody, you must provide a copy of the court order granting sole custody to the applying parent (unless child’s travel is restricted by that order).
The U.S. Customs and Border Protection strongly recommend having the other parent’s written permission if it is not included in the court order as many other countries may require it.
International parenting time and travel have unique challenges. Children may leave the country without restriction, but cannot return without proof of citizenship. Passports and visas are required. The primary custodial parent should safeguard these documents and make them easily available to the other parent at the scheduled times and places of exchange for foreign travel. Likewise, the documents should be returned promptly at the conclusion of parenting time. The noncustodial parent should keep copies of important travel documents. For the latest requirements, review the crossing borders section of the U.S. Department of Homeland Security web page. For long‐term planning, review the information found in the U.S. Department of State Office of Children’s Issues. For more information, visit U.S. Department of State Passports for Minors Under 16.