Mo. Rev. Stat. § 139.055: Tax paid by credit card or electronic transfer — fee.

Any county or public water supply district may accept payment by credit card or electronic transfers of funds for any tax, fee, or license payable to the county or district. A county collector or district shall not be required to accept payment by credit card if the credit card bank, processor, or issuer would charge the county or district a fee for such payment. However, a county or district may accept payment by credit card and charge the person making such payment by credit card a fee equal to the fee charged the county or district by the credit card bank, processor, issuer for such payment. A county or district may accept payment by electronic transfer of funds in payment of any tax, fee, or license and charge the person making such payment a fee equal to the fee charged the county or district by the bank, processor, or issuer of such electronic payment.