Mo. Rev. Stat. § 144.620
For the purpose of the proper administration of sections 144.600 to 144.745 and to prevent evasion of the tax and the duty to collect the tax, it shall be presumed that tangible personal property sold by any vendor for delivery in this state or transportation to this state is sold for storage, use or consumption in this state unless the vendor takes from the purchaser a certificate signed by and bearing the name and address of the purchaser to the effect that the property was purchased for resale, and it shall also be presumed that tangible personal property shipped, mailed, expressed, transported or brought to this state by the purchaser was purchased from a vendor after the effective date of this law for storage, use or consumption in this state.
§ 144.620, RSMo