Mo. Rev. Stat. § 53.135: Travel expenses (third and fourth class counties).

The county assessor in counties of the third and fourth classification shall be allowed a reimbursement for actual and necessary travel expenses incurred in the performance of the assessor's official duties within the county at the rate allowed pursuant to subsection 11* of section 50.333, payable monthly upon the filing of a statement by the assessor with the county commission showing the actual and necessary miles traveled during the month, to be paid out of the county treasury.