Mo. Rev. Stat. § 249.620: Collector shall pay holder of tax bill.

After any such tax bill or any installment has been paid to the county collector, he shall pay the amount of such payment to the holder of the special tax bill and shall cancel and preserve any such tax bill presented to him, or if only an installment of said tax bill has been paid, shall have the holder of such tax bill endorse the receipt of the amount of said tax bill upon the back of said tax bill, and when the last installment shall have been paid, mark such tax bill cancelled and preserve the same.