Mo. Rev. Stat. § 138.011: Board of equalization members, restriction on being certain local officials or school board members (charter counties).

No member of any board of equalization in any county with a charter form of government shall be an official of any city, town, or village in the county, a member of any school board in the county, or an employee of any school district within the county. Each member shall have some level of experience as determined by the governing authority of the county as a real estate broker, real estate appraiser, home builder, property developer, lending officer, or investor in real estate before their appointment to the board.