Mo. Rev. Stat. § 104.395
Option 1.
An actuarial reduction approved by the board of the member's annuity in reduced monthly payments for life during retirement with the provision that upon the member's death the reduced annuity at the date of the member's death shall be continued throughout the life of, and be paid to, the member's spouse to whom the member was married at the date of retirement and who was nominated by the member to receive such payments in the member's application for retirement or as otherwise provided pursuant to subsection 5 of this section. Such annuity shall be reduced in the same manner as an annuity under option 2 as in effect immediately prior to August 28, 1997. The surviving spouse shall designate a beneficiary to receive any final monthly payment due after the death of the surviving spouse; or
Option 2.
The member's normal annuity in regular monthly payments for life during the member's retirement with the provision that upon the member's death a survivor's benefit equal to one-half the member's annuity at the date of the member's death shall be paid to the member's spouse to whom the member was married at the date of retirement and who was nominated by the member to receive such payments in the member's application for retirement or as otherwise provided pursuant to subsection 5 of this section, in regular monthly payments for life. The surviving spouse shall designate a beneficiary to receive any final monthly payment due after the death of the surviving spouse; or
Option 3.
An actuarial reduction approved by the board of the member's normal annuity in reduced monthly payments for the member's life with the provision that if the member dies prior to the member having received one hundred twenty monthly payments of the member's reduced annuity, the member's reduced annuity to which the member would have been entitled had the member lived shall be paid for the remainder of the one hundred twenty months' period to such beneficiary as the member shall have nominated by written designation duly executed and filed with the board. If there is no such beneficiary surviving the retirant, the reserve for such annuity for the remainder of such one hundred twenty months' period shall be paid as provided under subsection 3 of section 104.620. If such beneficiary dies after the member's date of death but before having received the remainder of the one hundred twenty monthly payments of the retiree's reduced annuity, the reserve for such annuity for the remainder of such one hundred twenty-month period shall be paid as provided under subsection 3 of section 104.620; or
Option 4.
An actuarial reduction approved by the board of the member's normal annuity in reduced monthly payments for the member's life with the provision that if the member dies prior to the member having received sixty monthly payments of the member's reduced annuity, the member's reduced annuity to which the member would have been entitled had the member lived shall be paid for the remainder of the sixty months' period to such beneficiary as the member shall have nominated by written designation duly executed and filed with the board. If there be no such beneficiary surviving the retirant, the reserve for such annuity for the remainder of such sixty months' period shall be paid as provided under subsection 3 of section 104.620. If such beneficiary dies after the member's date of death but before having received the remainder of the sixty monthly payments of the retiree's reduced annuity, the reserve for such annuity for the remainder of the sixty-month period 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 date retirement benefits are initiated if the member makes such election within one year from the date of marriage or July 1, 2000, whichever is later, under any of the following circumstances:
9. If a member designates a spouse as a beneficiary pursuant to option 1 or option 2 of subsection 1 of this section and subsequently that marriage ends as a result of a dissolution of marriage, such dissolution shall not affect the option election pursuant to this section and the former spouse shall continue to be eligible to receive survivor benefits upon the death of the member, except a member may cancel his or her election if:
(2) The dissolution of marriage of the member and former spouse occurred prior to January 1, 2021, and:
(b) The dissolution decree does not provide for the sole retention by the member of all rights in the annuity and the parties obtain an amended or modified dissolution decree after January 1, 2021, which provides for the sole retention by the member of all rights in the annuity and provides that the former spouse shall not be entitled to any survivor benefits pursuant to this chapter.
Upon meeting the requirements of subdivision (1) or (2) of this subsection, the monthly benefit payable for the lifetime of the member shall be the actuarial equivalent of the annuity payable pursuant to the provisions of option 1 or option 2 of subsection 1 of this section, as adjusted for early retirement if applicable. In no event shall the monthly benefit payable for the lifetime of the member be greater than the amount that would have been payable to the member under subsection 3 or 4 of this section, whichever is applicable, had the former spouse died on the date of the dissolution of marriage. Any increase in the annuity amount shall be prospective and effective the first of the month following the date of receipt by the system of a certified copy of the dissolution decree that meets the requirements of this subsection.
(L. 1967 p. 191, A.L. 1972 S.B. 548, A.L. 1981 H.B. 835, et al., A.L. 1984 H.B. 1370, A.L. 1986 H.B. 1496, A.L. 1988 H.B. 1643 & 1399, A.L. 1994 H.B. 1149, A.L. 1995 H.B. 416, et al., A.L. 1997 H.B. 356, A.L. 1999 S.B. 308 & 314, A.L. 2000 H.B. 1808, A.L. 2001 S.B. 371, A.L. 2007 S.B. 406, A.L. 2013 H.B. 233, A.L. 2020 H.B. 1467 & H.B. 1934)