A common misconception is that there is a magic age when children can simply tell a judge they want to live with one parent over the other, and that is the end of the case. This is not true. A child’s wishes as to who her custodian would be is one of eight factors a court must consider in making a custody decision. A custody order must be in the child’s best interest. What a child wishes may be contrary to that child’s best interest. A Parenting Plan is not required for children 18 and over, so it could be said that the answer to this question is 18.