Mo. Rev. Stat. § 53.270

Any county assessor who has served for sixteen or more years as an assessor shall be exempt from attending or completing any course of study or classroom instruction required by this chapter to receive any additional compensation. Such assessor shall receive all increases in compensation granted to county assessors who complete such classroom instruction or course of study. If such assessor elects to attend or complete such study or classroom instruction his expenses shall be reimbursed.