Mo. Rev. Stat. § 139.400
If the collector-treasurer in any county that has adopted township organization shall be unable to collect any taxes charged in the tax list, by reason of the removal or insolvency of the person to whom such tax may be charged, or on account of any error in the tax list, the collector-treasurer shall deliver to the county clerk his or her tax book, and shall submit and file with said clerk, at the time of his or her settlement, a statement in writing, setting forth the name of the person charged with such tax, the value of the property, and the amount of tax so charged and the cause of the delinquency, and shall make oath before the county clerk, or some associate circuit judge, that the facts stated in such statement are true and correct, and that the sums mentioned therein remain unpaid, and that the collector-treasurer used due diligence to collect the same, which oath or affidavit shall be signed by the collector-treasurer; and upon filing said statement, the county clerk shall allow the collector-treasurer credit for the amount of taxes therein stated, and shall apportion and credit the same on the several funds for which such tax was charged; and when the collector-treasurer makes settlement with the county commission, such statement shall be a sufficient voucher to entitle the collector-treasurer to credit for the amount therein stated; but in no case shall any collector-treasurer, county clerk, or county treasurer, be entitled to abatement on the resident tax list until the statement and affidavit aforesaid are filed as required by this chapter.
§ 139.400, RSMo