An election under this section may provide for a survivor benefit based on all or any portion of that part of the annuity of the participant which is not designated or committed as a base for survivor benefits for a spouse or any other former spouse of the participant. The participant and his or her spouse may make an election under section 4046(b)(1)(B) of this title prior to the time of retirement for the purpose of allowing an election to be made under this section.
22 U.S. Code § 4159 - Survivor benefits for certain former spouses
(a) Eligible participants; election of benefits
(b) Time of election
(c) Portion of annuity as basis for benefits
(d) Amount of reduction; effective dateThe amount of the reduction in the participant’s annuity shall be determined in accordance with section 4046(b)(2) of this title. Such reduction shall be effective as of—
the commencing date of the participant’s annuity, in the case of an election under subsection (b)(1), or