Mo. Rev. Stat. § 321.130
A person, to be qualified to serve as a director, shall be a resident and voter of the district for at least one year before the election or appointment and be over the age of twenty-four years. In the event the person is no longer a resident of the district, the person's office shall be vacated, and the vacancy shall be filled as provided in section 321.200. Nominations and declarations of candidacy shall be filed at the headquarters of the fire protection district by paying a filing fee equal to the amount of a candidate for county office as set forth under section 115.357, and filing a statement under oath that such person possesses the required qualifications. Thereafter, such candidate shall have the candidate's name placed on the ballot as a candidate for director.
§ 321.130, RSMo