Two uniform acts govern almost every custody and support question that crosses a state line, and both work by giving exactly one state the authority to act. This subject covers how a home state is identified, the narrow emergency exception, what registering an order in a second state does and does not achieve, which state may modify an order later, and how a parent may relocate without losing the case.
An existing custody determination can be registered in another state by filing a letter of request, two copies of the order including one certified, a sworn statement that it has not been modified, and the parties' addresses. The receiving court files it and serves notice on the other party, who has a short period to contest on narrow grounds. Registration confirms enforceability; it does not confer any power to modify the order.
Interstate custody law requires a court to check, before hearing a case, whether a proceeding concerning the same child is already pending elsewhere. Where one is, the court must stay its own proceeding and communicate with the other court, and it may not exercise jurisdiction if the other proceeding was commenced in a state with jurisdiction under the framework. Parties are required to disclose prior and pending proceedings in their first pleading, on pain of the court declining to act.
A state other than the issuing state may modify a child support order only where two conditions are met. Nobody — neither parent nor the child — may still reside in the issuing state, and the party seeking modification must be a non-resident of the state being asked to act, with the respondent subject to that state's personal jurisdiction. The effect is that a parent seeking a change files where the other parent lives.
A majority of states require a parent intending to relocate with a child to give the other parent written notice, typically sixty days in advance, stating the new address, the date of the intended move, the reasons, and a proposed revised schedule. The other parent then has a defined period to object, and an objection generally triggers a hearing at which the court applies the state's relocation standard.
An income withholding order issued in one state may be sent directly to an employer in another, which must treat it as though issued locally. No registration and no second proceeding are required. The employer applies its own state's law to mechanical questions — payment timing, the fee it may retain, the maximum proportion of pay and priority among competing orders — and the issuing state's law to what is actually owed.
The six-month period is counted backwards from the day the proceeding began and must be consecutive, but a temporary absence from the state counts as part of the period rather than breaking it. That single allowance carries most of the difficulty: courts must decide whether a given absence was a pause or a departure, and they do it on the surrounding arrangements rather than on stated intentions. A separate rule covers children under six months old.
Temporary emergency jurisdiction allows a court in the state where a child is physically present to enter protective orders where the child has been abandoned or where protection is necessary because the child, a sibling or a parent is subjected to or threatened with mistreatment or abuse. It is deliberately narrow and deliberately temporary.
The uniform interstate support framework operates on a one-order principle: whatever the procedural history, a single order controls prospectively. Where only one order exists, it controls. Where several exist, the rules look first at whether any issuing state has continuing exclusive jurisdiction; if one does, its order controls. If several do, the order from the child's current home state controls, and failing that the most recently issued.
A parent seeking enforcement of a custody determination in another state files a verified petition, and the court sets a hearing on the next judicial day where possible. At that hearing the court orders immediate delivery of the child unless the respondent establishes a short list of matters: that the issuing court lacked jurisdiction, that the order has been vacated, stayed or modified, or that notice was not given. The merits of custody are outside the hearing entirely.
A state that has made an initial custody determination retains exclusive continuing jurisdiction to modify it. That jurisdiction ends in two situations: where the issuing court determines that neither the child nor the child and a parent have a significant connection with the state and substantial evidence is no longer available there, or where any court determines that the child and both parents no longer reside in the state.
The uniform act governing interstate custody assigns initial jurisdiction to the child's home state, defined as the state where the child lived with a parent or person acting as a parent for at least six consecutive months immediately before the proceeding began. For a child under six months old, the home state is where the child has lived since birth. Temporary absences count as part of the period rather than breaking it.
