Mo. Rev. Stat. § 104.1027
Option 1.
A retiree's life annuity shall be reduced to a certain percent of the annuity otherwise payable. Such percent shall be ninety percent adjusted as follows: if the retiree's age on the annuity starting date is younger than sixty-two years, an increase of three-tenths of one percent for each year the retiree's age is younger than age sixty-two years; and if the beneficiary's age is younger than the retiree's age on the annuity starting date, a decrease of three-tenths of one percent for each year of age difference; and if the retiree's age is younger than the beneficiary's age on the annuity starting date, an increase of three-tenths of one percent for each year of age difference; provided, after all adjustments the option 1 percent cannot exceed ninety-five percent. Upon the retiree's death, fifty percent of the retiree's reduced annuity shall be paid to such beneficiary who was the retiree's spouse on the annuity starting date or as otherwise provided by subsection 5 of this section.
Option 2.
A retiree's life annuity shall be reduced to a certain percent of the annuity otherwise payable. Such percent shall be eighty-three percent adjusted as follows: if the retiree's age on the annuity starting date is younger than sixty-two years, an increase of four-tenths of one percent for each year the retiree's age is younger than sixty-two years; and if the beneficiary's age is younger than the retiree's age on the annuity starting date, a decrease of five-tenths of one percent for each year of age difference; and if the retiree's age is younger than the beneficiary's age on the annuity starting date, an increase of five-tenths of one percent for each year of age difference; provided, after all adjustments the option 2 percent cannot exceed ninety percent. Upon the retiree's death one hundred percent of the retiree's reduced annuity shall be paid to such beneficiary who was the retiree's spouse on the annuity starting date or as otherwise provided by subsection 5 of this section.
Option 3.
A retiree's life annuity shall be reduced to ninety-five percent of the annuity otherwise payable. If the retiree dies before having received one hundred twenty monthly payments, the reduced annuity shall be continued for the remainder of the one hundred twenty-month period to the retiree's designated beneficiary provided that if there is no beneficiary surviving the retiree, the present value of the remaining annuity payments shall be paid as provided under subsection 3 of section 104.620. If the beneficiary survives the retiree but dies before receiving the remainder of such one hundred twenty monthly payments, the present value of the remaining annuity payments shall be paid as provided under subsection 3 of section 104.620.
Option 4.
A retiree's life annuity shall be reduced to ninety percent of the annuity otherwise payable. If the retiree dies before having received one hundred eighty monthly payments, the reduced annuity shall be continued for the remainder of the one hundred eighty-month period to the retiree's designated beneficiary provided that if there is no beneficiary surviving the retiree, the present value of the remaining annuity payments shall be paid as provided under subsection 3 of section 104.620. If the beneficiary survives the retiree but dies before receiving the remainder of such one hundred eighty monthly payments, the present value of the remaining annuity payments shall be paid as provided under subsection 3 of section 104.620.
5. Effective July 1, 2000, a member may make an election under option 1 or 2 after the annuity starting date as described in this section if the member makes such election within one year from the date of marriage or July 1, 2000, whichever is later, pursuant to any of the following circumstances:
(L. 1999 S.B. 308 & 314, A.L. 2000 H.B. 1808, A.L. 2001 S.B. 371, A.L. 2007 S.B. 406)