Mo. Rev. Stat. § 140.530: Invalidity of sale, when.

No sale or conveyance of land for taxes shall be valid if at the time of being listed such land shall not have been liable to taxation, or, if liable, the taxes thereon shall have been paid before sale, or if the description is so imperfect as to fail to describe the land or lot with reasonable certainty and for the first two enumerated causes, the money paid by the purchaser at such void sale shall be refunded, with interest, out of the county treasury, on order of the county commission.