22 C.F.R. § 19.11-1
If a participant or former participant dies in active service or after retirement, regular survivor annuities are payable under terms of this section to an eligible surviving spouse, former spouse or child. Also, if all rights to annuity and survivor annuity terminate prior to exhaustion of the participant's lump-sum credit, a lump-sum payment is made pursuant to § 19.13 . In addition to the above, an additional survivor annuity, and a supplemental survivor annuity may be payable to an eligible survivor under §§ 19.10-5 and 19.10-6 , respectively. If any participant or former participant makes an election, files a spousal agreement or becomes subject to a court order to provide a regular survivor annuity for a spouse or former spouse and does not subsequently become entitled to leave a survivor annuity under these regulations (because of separation from the Service and withdrawal of contributions, death after separation but before commencement of a deferred annuity, or for any other reason), none will be paid and such election, spousal agreement or court order to provide such survivor annuity will have no force or effect.
22 C.F.R. §19.11-1