(1) The administrative hearing provided in the act is limited to the determination of whether income withholding, including the amounts to be withheld, is improper because of a mistake of fact. To accomplish this purpose, and to facilitate the speedy resolution of disputes relating to income withholding, the obligor must state in his hearing request a mistake of fact which constitutes grounds upon which the request is based. If the obligor fails to state such grounds, the department may deny the hearing because there is no issue upon which a hearing may be granted.

(2) For purposes of this section, a "mistake of fact" shall be defined to include the following:

(a) mistakes concerning the identity of the obligor;

(b) mistakes concerning the existence or amount of the support obligation;

(c) mistakes in the determination that delinquent support amounts owed are equal to or greater than one month's support; and

(d) mistakes in the computation of delinquent support amounts owed.