Mo. Rev. Stat. § 86.1420

86.1420. Benefits and administrative expenses to be paid by system funds — commencement of base pension, when — death of member, effect of. — 1. All benefits and all necessary administrative expenses of the retirement system shall be paid from the funds of the retirement system.

2. The base pension of a member who, after August 28, 2011, retires from or otherwise terminates active service with entitlement to a base pension under sections 86.1310 to 86.1640 shall commence as of the first day of the month next following such retirement or termination with no proration of such pension for the month in which such retirement or termination occurs. The supplemental retirement benefit of a member who, after August 28, 2011, retires from or otherwise terminates active service with entitlement to a supplemental retirement benefit provided in subsection 1 of section 86.1600 shall commence as of the first day of the month next following such retirement or termination with no proration of such supplemental retirement benefit for the month in which such retirement or termination occurs.

3. Upon the death of a member in service who leaves a surviving spouse, as defined in section 86.1310 , entitled to benefits, any base pension which such surviving spouse shall elect under subdivision (2) of subsection 1 of section 86.1610 or under paragraph (b) of subdivision (3) of subsection 1 of section 86.1610 shall commence the later of the first day of the month next following such death or the first day of the month following the date which would have been the member's earliest possible retirement date permitted under subsections 2 or 3 of section 86.1540 with no proration of such pension for the month prior to such commencement date. Any base pension which such surviving spouse shall elect under paragraph (c) of subdivision (3) of subsection 1 of section 86.1610 shall commence the first day of the month next following such death with no proration of such pension for the month prior to such commencement date.

4. Upon the death of a member who is receiving a base pension under sections 86.1310 to 86.1640 leaving a surviving spouse, as defined in section 86.1310 , entitled to benefits, the pension of such surviving spouse shall commence on the first day of the month next following such death with no proration for the month in which such death occurs.

5. All payments of any benefit shall be paid on the first business day of each month for that month. For any benefit under sections 86.1310 to 86.1640 , the retirement system shall withhold payment of such benefit until all requisite documentation has been filed with the retirement system evidencing the entitlement of the payee to such payment. The final payment due to a retired member shall be the payment due on the first day of the month in which such member's death occurs. The final payment due to any surviving spouse shall be the payment due on the first day of the month in which such surviving spouse dies or otherwise ceases to be entitled to benefits under sections 86.1310 to 86.1640 .

6. If no benefits are otherwise payable to a surviving spouse of a deceased member or otherwise as provided in this section, the member's accumulated contributions, to any extent not fully paid to such member prior to the member's death or to the surviving spouse of such member or otherwise as provided in this section, shall be paid in one lump sum to the member's beneficiary named by such member in a writing filed with the retirement system prior to the member's death for the purpose of receiving such benefit, and if no beneficiary is named, then to such member's estate. Such payment shall constitute full and final payment of any and all claims for benefits under the retirement system, except as provided in section 86.1620 .

(L. 2005 H.B. 323, A.L. 2011 H.B. 183 merged with H.B. 282, A.L. 2013 H.B. 116 merged with H.B. 418)