Family Code § 5700.506
CHAPTER 5. Enforcement of Support Order Without Registration
(a) An obligor may contest the validity or enforcement of an income-withholding order issued in another state and received directly by an employer in this state by registering the order in a tribunal of this state and filing a contest to that order as provided in Chapter 6, or otherwise contesting the order in the same manner as if the order had been issued by a tribunal of this state.
(b) The obligor shall give notice of the contest to:
(1) a support enforcement agency providing services to the obligee;
(2) each employer that has directly received an income-withholding order relating to the obligor; and
(3) the person designated to receive payments in the income-withholding order or, if no person is designated, to the obligee.