Choice of Law: Which Guideline Applies?

When a case stretches across state lines, you may wonder whose rules set the amount, duration, and interest. UIFSA splits the answer: enforcement follows the law of the enforcing state, but core terms of the obligation usually follow the issuing state—unless a valid modification occurs elsewhere. Here’s how to navigate the puzzle.

Amount and duration pre‑modification. As long as the original issuing state retains continuing exclusive jurisdiction (CEJ), its law controls the guideline amount, duration (age of majority, emancipation triggers), and sometimes interest on each missed installment. Another state enforcing the order cannot change these terms while CEJ remains in the issuing state.

After a valid modification. Once a new state with proper jurisdiction modifies the order, that new state’s law governs the amount going forward. Elements tied to the life of the obligation (e.g., duration) may still follow the original state’s law in some scenarios; check statutes and UIFSA commentary in your jurisdiction.

Enforcement procedures. Garnishment limits, employer deadlines, lien recording, and license suspension procedures follow the enforcing state’s law. For example, a state with a lower disposable‑earnings cap will apply its cap even when enforcing a different state’s order.

Interest calculations. Interest rules can be tricky. Some states apply the issuing state’s interest rate to arrears that accrued there; others apply the enforcing state’s rate after registration. When in doubt, ask the court to specify the applicable rate in the registration or arrearage judgment so accounting stays consistent.

Drafting orders to reduce conflict. Good orders name the controlling state, cite the guideline used, and specify interest rates and application-of-payment rules. When registering or modifying, include a paragraph clarifying which state’s law governs which element—amount, duration, interest, and enforcement actions. This one paragraph can prevent years of confusion.

Practical tips.

• Identify CEJ first; it drives which guideline applies. 

• In arrears judgments, state the rate and method used to compute interest “as of” a date. 

• When registering, attach a memo for the clerk that flags duration rules (e.g., support ends at 19 if still in high school) so the enforcing state doesn’t assume its own age-of-majority rule.

Bottom line. Choice of law in support cases is not “winner takes all.” Amount and duration generally track the issuing state until a valid modification; enforcement mechanics follow the enforcing state. Put the rules in writing to keep ledgers synchronized across borders.



Decision tree.

1) Does the issuing state still have CEJ? If yes → its guideline and duration control amount/duration; enforcing state’s law controls procedures. 

2) Was there a valid modification in a new state? If yes → new state’s guideline controls going forward; clarify duration and interest in the order. 

3) Are you entering an arrearage judgment? State in the judgment which law set the interest rate and calculation method.

Worked example. An order from State M (interest 10% simple, support ends at 18/HS). After registration in State N (interest 5% simple, support ends at 19), enforcement proceeds in State N using its garnishment caps, but arrears interest through the date of registration is computed at 10% per State M. If State N later validly modifies, new amounts apply prospectively, but duration may still track State M if its statute says so. Put these specifics in the order to prevent dueling ledgers.