Per U.S. Soccer and United States Youth Soccer:
For the purposes of registration on gender-based amateur teams, a player may register with the gender team with which the player identifies, and confirmation sufficient for guaranteeing access shall be satisfied by documentation or evidence that shows the stated gender is sincerely held, and part of a person’s core identity. Documentation satisfying the herein-stated standard includes, but is not limited to, government-issued documentation or documentation prepared by a healthcare provider, counselor, or other qualified professional not related to the player.