What determines where I can file a child support case?

Jurisdiction to Determine and Modify Child Support.

Regardless of where child custody and visitation issues may properly be  litigated, in order for a state to determine issues of child support, only that state which satisfies one of the requirements provided in the Uniform Interstate Family Support Act (UIFSA) can issue a valid order of child support.

Jurisdiction under UIFSA is established if the person against whom a child support order is sought:

(1) is personally served with process within the state; or
(2) submits to the jurisdiction of the state’s courts; or
(3) resided with the subject child within the state; or
(4) resided in the state and provided prenatal expenses or support to the child; or
(5) has caused the child to reside in this state by the alleged obligor’s acts and directives; or
(6) engaged in sexual intercourse in the state and the child may have been conceived as a result of that act of sexual intercourse; or
(7) asserted parentage in the putative father registry maintained by the state SRS; or
(8) is subject to personal jurisdiction on any other constitutionally sound basis.

Every state has enacted and must comply with the provisions of the Uniform Interstate Family Support Act (UIFSA) in determining its jurisdiction to issue orders for child support.

Once both parents and the child have moved out of the state that issued any initial child support order, the original state automatically loses its jurisdiction to modify any orders for child support (although it may continue to enforce the child support orders issued by it or any other court having jurisdiction). Instead, the parent seeking to modify child support must  file the request for modification in the state in which that other parent lives. Notwithstanding the fact that the amount of child support will then be determined by that new state, the duration that child support would be paid is conclusively established by the laws of the state in which the child support order originated.