Section 831.645 - Elections between survivor annuities(a) A current spouse annuity cannot be reinstated under § 831.644 unless- (1) The surviving spouse elects to receive the reinstated current spouse annuity instead of any other payments (except any accrued but unpaid annuity and any unpaid employee contributions) to which he or she may be entitled under CSRS, or any other retirement system for Government employees, by reason of the remarriage; and(2) Any lump sum paid on termination of the annuity is returned to the Civil Service Retirement and Disability Fund.(b) A current spouse is entitled to a current spouse annuity based on an election under § 831.631 only upon electing this current spouse annuity instead of any other payments (except any accrued but unpaid annuity and any unpaid employee contributions) to which he or she may be entitled under CSRS, or any other retirement system for Government employees.(c) A former spouse who marries a retiree is entitled to a former spouse annuity based on an election by that retiree under § 831.632 , or § 831.682 , or a qualifying court order terminating that marriage to that retiree only upon electing this former spouse annuity instead of any other payments (except any accrued but unpaid annuity and any unpaid employee contributions) to which he or she may be entitled under CSRS, or any other retirement system for Government employees.(d) As used in this section, "any other retirement system for Government employees" does not include Survivor Benefit Payments from a military retirement system or social security benefits.55 FR 9103, Mar. 12, 1990, as amended at 58 FR 52881, Oct. 13, 1993. Redesignated at 58 FR 52882, Oct. 13, 1993