Iowa Code § 252D.9: Sums subject to immediate withholding.

Specified sums shall be deducted from the obligor’s income sufficient to pay the support obligation and any judgment established or delinquency accrued under the support order. The amount withheld pursuant to an income withholding order or notice of order for income withholding shall not exceed the amount specified in 15 U.S.C. §1673(b).