Like most aspects of child custody in Washington State, this decision is made according to the best interests of the child. With that in mind, the answer depends very much on the particulars of your individual case. The court may ask the following questions: Is the child old enough to have a say in the matter? Is the child’s other parent still in the child’s life? How would a surname change affect the child at this time? How long has the child had his or her current surname? Will the child’s name differ from other surnames in his or her household? Will the child’s name change affect his or her relationship with one parent?