Mo. Rev. Stat. § 148.461

In any legal contest concerning the amount of tax under sections 148.320, 148.340, and 148.370 for a calendar year, the quarterly installments for the following year shall continue to be made based upon the amount assessed by the director of revenue for the year in question. If after the end of any taxable year, the amount of the actual tax due is less than the total amount of the installments actually paid, the amount by which the amount paid exceeds the amount due shall be credited against the tax for the following year and deducted from the quarterly installment otherwise due on June first.