Wis. Stat. § 49.776: Payment of support arrears.

If a custodial parent who formerly received payments under s. 49.775 but who is no longer receiving payments under s. 49.775 assigned to the state under s. 49.775 (2) (bm) his or her right or the right of the dependent child to support from any other person, the department shall pay to the custodial parent all money in support arrears that is collected by the department after the custodial parent’s receipt of payments under s. 49.775 ceased and that accrued while the custodial parent was receiving those payments.