If the department has previously sent a notice of assignment and opportunity for hearing on the same support order under section 48-647, the county attorney, authorized attorney, or the department shall state the amount to be withheld from an obligor's disposable income pursuant to section 43-1722 and shall notify the obligor's employer or other payor pursuant to section 43-1723. If the department has not previously sent such notice, and except in cases in which the court has ordered income withholding pursuant to subsection (1) of section 43-1718.01 or section 43-1718.02, upon receiving certification pursuant to section 42-358 or notice of delinquent payments of medical support, the county attorney, the authorized attorney, or the department shall send a notice by certified mail to the last-known address of the obligor stating:
(1) That an assignment of his or her income by means of income withholding will go into effect within fifteen days after the date the notice is sent;
(2) That the income withholding will continue to apply to any subsequent employer or other payor of the obligor;
(3) The amount of support and any monetary judgment the obligor owes;
(4) The amount of income that will be withheld; and
(5) That within the fifteen-day period, the obligor may request a hearing in the manner specified in the notice to contest a mistake of fact. For purposes of this subdivision, mistake of fact shall mean (a) an error in the amount of current or overdue support or the amount of any monetary judgment, (b) an error in the identity of the obligor, or (c) an error in the amount to be withheld as provided in section 43-1722.