35 Miss. Code R. § 6-02-06-400.02
At the end of the update cycle, the county must have equalized values within the county so that similar properties have been assigned similar values, and that the relationships among all property values are correct. Counties must have completed an index study as provided in the appraisal manual and submitted it to the property tax office by April 1 of the update year providing adequate sales exist. If the study indicates a new index is justified, it must be implemented during the update year. If any county does not have adequate sales to complete the index study, the county must implement the state index. Property values on the tax roll must reflect the updated values shown on the property record cards. Additionally, counties must complete sales ratio studies, and the ratios must fall within accepted parameters as shown elsewhere in this rule. Counties must also physically observe all parcels on the 25 percent (including all real property which is required to be on the roll as of January 1st) list to insure correct depreciation, and such observed depreciation must be used on structures with an age of twenty (20) years or more. The tax roll must include all real property which is required to be on the roll as of January 1st.
35 Miss. Code. R. § 6-02-06-400.02