Revised Statutes of Missouri 137.075
Every person owning or holding real property or tangible personal property on the first day of January, including all such property purchased on that day shall be liable for taxes thereon during the same calendar year.
Revised Statutes of Missouri 137.340
Every person, corporation, partnership or association owning or controlling tangible personal property shall file with the assessor of the county an itemized return listing all the tangible personal property so owned or controlled on January 1st. Personal property must be reported in the county where you resided on January 1st.