(a) The payment of public assistance to or on behalf of a child creates a debt due and owing the state by the parent or parents responsible for the support of the child. The amount of the debt is the amount necessary to meet the total needs of the child or children and the person having custody, if included in the public assistance grant, as determined by the department in conformity with the federal Social Security Act; provided, however, that, where a court has ordered child support incident to a final divorce or in a criminal proceeding for nonsupport or where the responsible parent has entered into a legally enforceable and binding agreement, the debt created shall be equal to the amount set in such decree, order, hearing, or agreement.

(b) The department, in accordance with rules established by the Board of Human Services, shall be authorized to waive, reduce, or negotiate the payment of unreimbursed public assistance if it is determined that good cause for nonpayment exists or that enforcement of the claim would result in substantial and unreasonable hardship to the parent or parents responsible for the support of the child against whom the claim exists. The rules established by the Board of Human Services shall consider the ability of the responsible party to support the child or children during the period that public assistance was provided and the current history of regularity of payment by the responsible party. This subsection shall not apply to any court order or decree requiring the repayment of public assistance; however, the department is authorized to petition the court for consideration of a modification of an order or decree based on factors contained in this subsection and in the rules established by the Board of Human Services relating to such unreimbursed public assistance.