Mo. Rev. Stat. § 50.350: Salaried officer to collect fees (second class counties).

1. It shall be the duty of every county officer, in all counties of the second class, who shall be paid an annual salary in lieu of all fees, penalties, commissions, charges, emoluments, and moneys due him or his office for any service performed, to charge, collect and receive, upon behalf of the county, every fee, penalty, commission, charge, emolument and money that accrues in his office for any service rendered, by virtue of any statute of this state, except such fees as are chargeable to the county.

2. Subsection 1 shall not be construed to prohibit the retention of the commission allowed to the collector in counties having less than one hundred thousand inhabitants for collection of levee and drainage district taxes as provided in section 52.275.