Domestic Relations usually sends a notice to the parties inquiring as to the child's status in school. Support will end the later of age 18 or graduation from high school. If you don't receive a notice, you can call your enforcement officer to notify them of the child's birthday or high school graduation. However, if there are arrears on the account, the account will remain open until the arrears are paid.
Pennsylvania law establishes that both parents are liable for the support of their children who are unemancipated and 18 years of age or younger. However, parents may be liable for the support of their children who are 18 years of age or older. For example, a support obligation may continue for a child who is 18 and still attending high school. When a child is emancipated, or over 18 years of age and no longer attending high school, one of the parents may file a "Petition for Modification of an Existing Support Order" to request that the child support order be stopped. Additionally, there may be other situations, such as the existence of physical or emotional challenges, when parents may be required to pay support for a child who is 18 years of age or older.
An emancipation inquiry is often sent to the parent receiving support prior to the child's 18th birthday. If you have other children on the support order, I suggest that you file a modification so the order can be recalculated.