If no family benefit is being paid pursuant to § 3-12C-907, a surviving spouse of a contributing foundation member who had acquired at least three years of contributory service or noncontributory service or who died while performing usual duties for the employer and who died after June 30, 2015, is, upon attaining the age of sixty-five, eligible to receive a surviving spouse benefit calculated as follows, whichever is applicable:
The surviving spouse benefit shall be paid, upon receipt of a completed application, in monthly installments for the life of the surviving spouse. If the surviving spouse is eligible at the time of the member's death, the benefit is effective the first day of the month following the date on which the member's contributory service terminates.
SDCL 3-12C-1115