(a) The court may order that, in addition to income withheld for current spousal maintenance, income be withheld from the disposable earnings of the obligor to be applied toward the liquidation of any arrearages.
(b) The additional amount withheld to be applied toward arrearages must be whichever of the following amounts will discharge the arrearages in the least amount of time:
(1) an amount sufficient to discharge the arrearages in not more than two years; or
(2) 20 percent of the amount withheld for current maintenance.
Official text of the Texas Family Code as published by the Texas Legislative Council.