S.D. Codified Laws § 3-12C-1109
Each member who retired before July 1, 2008, and each beneficiary of a deceased member who retired prior to July 1, 2008, shall receive a retirement benefit based on the provisions of § 3-12C-1106, 3-12C-1107, or 3-12C-1108 as applicable based on the member's final average compensation, credited service, and other public benefits at retirement and the benefit formulas in §§ 3-12C-1106, 3-12C-1107, and 3-12C-1108 when increased by the COLA from the date of retirement to July 1, 2008.
Increased benefits as provided by any amendment to this section are prospective in nature and are effective July 1, 2008.
Each member or beneficiary of a member who retired before July 1, 1974, who is receiving benefits pursuant to § 3-12C-1605 or each member or beneficiary of a member who elected to retire pursuant to § 3-12C-1606, shall have a benefit increased by an additional two percent as of July 1, 2008, in lieu of the increase provided in this section.
If a member retired before normal retirement age, the benefit shall be adjusted in accordance with the law in effect at the time of retirement. If a member elected an alternate method of payment under the law in effect at the time of retirement, the benefit shall be adjusted in accordance with the law in effect at the time of retirement. If the additional benefit is to be paid to a beneficiary of a deceased member, the additional benefit shall be adjusted in accordance with the law in effect at the time of the member's retirement.
No member or beneficiary whose retirement benefit terminated before July 1, 2008, may receive any benefits pursuant to this section.
SDCL 3-12C-1109