Mo. Rev. Stat. § 92.112
As referred to in sections 92.110 and 92.210, the terms salaries, wages, commissions and other compensation shall not include any contributions to any deferred compensation plans, such as but not limited to, any salary reduction plans, cafeteria plans or any other similar plans deferring the receipt of compensation by a resident or nonresident if such contribution is not subject to Missouri state income tax at the time such contribution is made.
(L. 1997 H.B. 331 § 1)