The child support age is the age children are when their non-custodial parent must pay child support. After the children reach a certain age, the non-custodial father is no longer required to pay child support. This age differs in each state, but in most states it is the age when a child becomes a legal adult. This age is typically 18. There are some circumstances in which the non-custodial parent must pay child support even after the age of 18, such as in those states where a child 'becomes legal age' at 21. Also, a non-custodial parent may have to continue paying child support until the children have finished college, because they will need the financial support of their parents to do so. To determine the child support age of children for sure, it's important that non-custodial parents speak with a child support attorney. These attorneys will know the child support laws and statutes in the state they practice in, and will be able to help the non-custodial parent understand his or her rights and options under the law.