Because people move frequently, it is quite common for one or both of the parties to be living in different states while a support order is still in effect. It is usually more effective to enforce a support order in the state where the paying party lives. The primary motivator to get them to pay is the court’s contempt power. It is easier for a court in the state where the person lives to use that power because it is easier for law enforcement personnel to take the person into custody and hold them until they pay.
The states are required to enforce each other’s court orders. So the procedure is that you file a certified copy of the support order in the local court where the paying party lives. If they are not in compliance, you ask that court to hold them in contempt. The local jail is available to keep them uncomfortable while they find the money to pay at least some of what is owed.