Mo. Rev. Stat. § 52.325
In addition to all other compensation provided by law, the collector of revenue in all first class counties not having a charter form of government and adjoining a first class county having a charter form of government shall receive four thousand dollars annually, payable in equal installments at the same time and in the same manner as other compensation for such collectors. The provisions of this section shall not become effective until the supreme court of the state of Missouri has issued an opinion stating that the state of Missouri is not required under the provisions of Sections 16 to 24 of Article X of the Missouri Constitution to pay increases in compensation granted to county officials by state statutes, when such increases in compensation are not granted because of the imposition of additional duties. Once the opinion of the supreme court required herein has been issued, this section shall be effective as of the date such opinion was issued or as of September 28, 1981, whichever date later occurs.
§ 52.325, RSMo