Mo. Rev. Stat. § 137.715

Each county assessor shall, subject to the approval of the governing body of the county, appoint the additional clerks and deputies that he or she deems necessary for the prompt and proper discharge of the duties of his office. A portion of the salaries of the clerks and deputies hired by each county assessor shall be paid by the state in accordance with sections 137.710 and 137.750, and the remainder of the salaries for such clerks and deputies shall be paid by the county in which they are employed.