Mo. Rev. Stat. § 52.250
The collectors in third class counties shall collect a fee of one-half of one percent of all current taxes collected, including current delinquent taxes, exclusive of all current railroad and utility taxes collected on behalf of the county, as compensation for mailing the statements and receipts. All fees collected pursuant to this section shall be collected on behalf of the county and shall be paid into the county treasury. Notwithstanding any provisions of law to the contrary, or any other provision of law in conflict with the provisions of this section, in all counties which become counties of the second or fourth classification after December 31, 2000, one-half of one percent of all current taxes collected, including current delinquent taxes allocable to each taxing authority within the county and the county shall continue to be deducted each year for mailing the statements and receipts, exclusive of all current railroad and utility taxes collected, and shall be deposited into the county general fund as required by this section as if the county had retained its classification as a county of either the third or the fourth classification. Collectors in third and fourth class counties are entitled to collect such fees immediately upon an order of the circuit court pursuant to section 139.031. If the protest is later sustained and a portion of the taxes so paid is returned to the taxpayer the county shall return that portion of the fee collected on the amount returned to the taxpayer. Such county collector may accept credit cards as proper form of payment of outstanding taxes due. No county collector may charge a surcharge for payment by credit card which exceeds the fee or surcharge charged by the credit card bank for its service.
§ 52.250, RSMo