Mo. Rev. Stat. § 140.320

Any purchaser at delinquent tax sale of any tract or lot of land, his heirs or assigns, who takes possession of any tract or lot of land within the redemption period shall be required to pay the taxes subsequently assessed on such tract or lot of land during the period of occupancy and within the redemption period, and upon failure so to do, or if he commit waste thereon, such purchaser, his heirs or assigns, shall forfeit all rights acquired by his certificate of purchase, so far as the tract or lot of land taken possession of is concerned.