So how long does your support order stay in effect? Generally speaking, the order lasts until the child legally emancipates. Usually this is until the age of majority which is 18 or if the child is still in high school, the child support will continue until he or she turns 19 or graduates from high school, which ever comes first. You may have to take court action to see that your child support obligation is formally stopped. An order may also stay in effect past the child’s 19th birthday if the child is mentally or physically disabled and continues to need financial support.