Mo. Rev. Stat. § 92.111

92.111. Limitation on imposition of earnings tax — definitions. — 1. After December 31, 2011, no city, including any constitutional charter city, shall impose or levy an earnings tax, except a constitutional charter city that imposed or levied an earnings tax on November 2, 2010, may continue to impose the earnings tax if it submits to the voters of such city pursuant to section 92.115 the question whether to continue such earnings tax for a period of five years and a majority of such qualified voters voting thereon approve such question, however, if no such election is held, or if in any election held to continue to impose or levy the earnings tax a majority of such qualified voters voting thereon fail to approve the continuation of the earnings tax, such city shall no longer be authorized to impose or levy such earnings tax except to reduce such tax in the manner provided by section 92.125 .

2. As used in sections 92.111 to 92.200 , unless the context clearly requires otherwise, the term "earnings tax" means a tax on the:

(1) Salaries, wages, commissions and other compensation earned by its residents;

(2) Salaries, wages, commissions and other compensation earned by nonresidents of the city for work done or services performed or rendered in the city;

(3) Net profits of associations, businesses or other activities conducted by residents;

(4) Net profits of associations, businesses or other activities conducted in the city by nonresidents;

(5) Net profits earned by all corporations as the result of work done or services performed or rendered and business or other activities.

(L. 2010 Adopted by Initiative, Proposition A, November 2, 2010 § 92.110)