Mo. Rev. Stat. § 140.360: Redemption — compensation for improvements — limitations.

1. In case any lasting and valuable improvements shall have been made by the purchaser at a sale for taxes, or by any person claiming under him, and the land on which the same shall have been made shall be redeemed as aforesaid, the premises shall not be restored to the person redeeming, until he shall have paid or tendered to the adverse party the value of such improvements; and, if the parties cannot agree on the value thereof the same proceedings shall be had in relation thereto as shall be prescribed in the law existing at the time of such proceedings for the relief of occupying claimants of lands in actions of ejectment.

2. No compensation shall be allowed for improvements made before the expiration of one year from the date of sale for taxes.