If the agency can withhold up to 60% of your income for mulitple cases, what percentage can they get for the arrears cases when the child support cases either stop or is dropped?

North Carolina General Statutes § 110-136
(a) Notwithstanding any other provision of the law, in any case in which a responsible parent is under a court order or has entered into a written agreement pursuant to G.S. 110‑132 or 110‑133 to provide child support, a judge of the district court in the county where the mother of the child resides or is found, or in the county where the father resides or is found, or in the county where the child resides or is found may enter an order of garnishment whereby no more than forty percent (40%) of the responsible parent's monthly disposable earnings shall be garnished for the support of his minor child.