Mo. Rev. Stat. § 105.684

105.684. Benefit increases prohibited, when — amortization of unfunded actuarial accrued liabilities — accelerated contribution schedule required, when. — 1. Notwithstanding any law to the contrary, no plan shall adopt or implement any additional benefit increase, supplement, enhancement, lump sum benefit payments to participants, or cost-of-living adjustment beyond current plan provisions in effect prior to August 28, 2007, which would, in aggregate with any other proposed plan provisions, increase the plan's actuarial accrued liability when valued by an actuary using the same methods and assumptions as used in the most recent periodic valuation, unless the plan's actuary determines that the funded ratio of the most recent periodic actuarial valuation and prior to such adoption or implementation is at least eighty percent and will not be less than seventy-five percent after such adoption or implementation. Methods and assumptions used in valuing such proposed change may be modified if the nature is such that alternative assumptions are clearly warranted.

2. The unfunded actuarial accrued liabilities associated with benefit changes described in this section shall be amortized over a period not to exceed twenty years for purposes of determining the contributions associated with the adoption or implementation of any such benefit increase, supplement, or enhancement.

3. Any plan with a funded ratio below sixty percent shall have the actuary prepare an accelerated contribution schedule based on a descending amortization period for inclusion in the actuarial valuation.

4. Nothing in this section shall apply to any plan established under chapter 70 or chapter 476 .

5. Nothing in this section shall prevent a plan from adopting and implementing any provision necessary to maintain a plan's status as a qualified trust pursuant to 26 U.S.C. Section 401(a).

(L. 2007 S.B. 406, A.L. 2013 H.B. 233, A.L. 2014 H.B. 1882)