Cal. FAM § 5700.605

(a) When a support order or income-withholding order issued in another state or a foreign support order is registered, the registering tribunal of this state shall notify the nonregistering party. The notice must be accompanied by a copy of the registered order and the documents and relevant information accompanying the order.

(b) A notice must inform the nonregistering party:

(1) that a registered support order is enforceable as of the date of registration in the same manner as an order issued by a tribunal of this state;

(2) that a hearing to contest the validity or enforcement of the registered order must be requested within 20 days after notice unless the registered order is under Section 5700.707;

(3) that failure to contest the validity or enforcement of the registered order in a timely manner will result in confirmation of the order and enforcement of the order and the alleged arrearages; and

(4) of the amount of any alleged arrearages.

(c) If the registering party asserts that two or more orders are in effect, a notice must also:

(1) identify the two or more orders and the order alleged by the registering party to be the controlling order and the consolidated arrears, if any;

(2) notify the nonregistering party of the right to a determination of which is the controlling order;

(3) state that the procedures provided in subsection (b) apply to the determination of which is the controlling order; and

(4) state that failure to contest the validity or enforcement of the order alleged to be the controlling order in a timely manner may result in confirmation that the order is the controlling order.

(d) Upon registration of an income-withholding order for enforcement, the support enforcement agency or the registering tribunal shall notify the obligor’s employer pursuant to Chapter 8 (commencing with Section 5200) of Part 5.