CA Civ Proc Code Section 706.031

(a)

Nothing in this chapter affects an earnings assignment order for support.

(b)

An earnings assignment order for support shall be given priority over any earnings withholding order. An employer upon whom an earnings assignment order for support is served shall withhold and pay over the earnings of the employee pursuant to the assignment order notwithstanding the requirements of any earnings withholding order. When an employer is required to cease withholding earnings pursuant to an earnings withholding order, the employer shall notify the levying officer who served the earnings withholding order that a supervening earnings assignment order for support is in effect.

(c)

Subject to subdivisions (b), (d), and (e), an employer shall withhold earnings of an employee pursuant to both an earnings assignment order for support and an earnings withholding order.

(d)

The employer shall withhold pursuant to an earnings withholding order only to the extent that the sum of the amount withheld pursuant to any earnings assignment order for support and the amount withheld pursuant to the earnings withholding order does not exceed the amount that may be withheld under Article 3 (commencing with Section 706.050).

(e)

The employer shall withhold pursuant to an earnings withholding order for taxes only to the extent that the sum of the amount withheld pursuant to any earnings assignment order for support and the amount withheld pursuant to the earnings withholding order for taxes does not exceed the amount that may be withheld under Article 4 (commencing with Section 706.070).