Fam. Code, § 5700.604

(a) Except as otherwise provided in subsection (d), the law of the issuing state or foreign country governs:

(1) the nature, extent, amount, and duration of current payments under a registered support order;

(2) the computation and payment of arrearages and accrual of interest on the arrearages under the support order; and

(3) the existence and satisfaction of other obligations under the support order.

(b) In a proceeding for arrears under a registered support order, the statute of limitation of this state, or of the issuing state or foreign country, whichever is longer, applies.

(c) A responding tribunal of this state shall apply the procedures and remedies of this state to enforce current support and collect arrears and interest due on a support order of another state or a foreign country registered in this state.

(d) After a tribunal of this state or another state determines which is the controlling order and issues an order consolidating arrears, if any, a tribunal of this state shall prospectively apply the law of the state or foreign country issuing the controlling order, including its law on interest on arrears, on current and future support, and on consolidated arrears.