Mo. Rev. Stat. § 454.554

If not required by an existing order, the division or circuit clerk shall notify by first class mail any obligor under a support order, and an employer or other payor who has or will be withholding income to direct support payments to the payment center. The division shall file a copy of the notice with the court with jurisdiction over the support order. Any obligor, employer or other payor who receives notice to direct payments to the payment center and thereafter fails to direct payments to the payment center shall receive a second written notice by certified mail, return receipt requested. Failure to pay the payment center after a second notice shall be grounds for contempt and a motion for contempt may be filed in the county or city not within a county in which the support order is filed.