Mo. Rev. Stat. § 143.821: Refund claim.

Every claim for refund shall be filed with the director of revenue in writing and shall state the specific grounds upon which it is founded. A taxpayer which has made a deposit under subsection 2 of section 143.631 and has received a determination of the director of revenue pursuant to section 143.641 shall be deemed for purposes of this chapter to have filed a claim for refund of an amount not greater than the deposit, on such grounds as were set forth in the taxpayer's protest filed under subsection 1 of section 143.631.