Mo. Rev. Stat. § 110.190
When the funds of any county are deposited with two or more banking corporations, or associations, as provided in section 110.180, the county commission shall select and name, by order, one of the banking concerns to act as a clearing house for the others, at which all checks drawn by the county treasurer upon the county funds shall be finally paid; and the bank so selected and acting as a clearing house shall be allowed a rebate on the amount of interest due from it to the county for funds deposited with it; but the rebate shall not exceed one-half of one percent per annum on the whole amount of county funds deposited with the banking concern, to be computed as provided in section 110.150 and to be deducted from the amount of interest due and payable monthly as provided in section 110.150.
§ 110.190, RSMo