22 U.S.C. § 4069a: Retirement benefits for certain former spouses

if married to the participant throughout the creditable service of the participant, equal to 50 percent of the benefits of the participant; or if not married to the participant throughout such creditable service, equal to that former spouse’s pro rata share of 50 percent of such benefits. the former spouse remarries before age 55; or the former spouse was not married to the participant at least 10 years during service of the participant which is creditable under this subchapter with at least 5 years occurring while the participant was a member of the Foreign Service. the day the participant upon whose service the benefits are based becomes entitled to benefits under this subchapter; or the first day of the month in which the divorce or annulment involved becomes final; and the last day of the month before the former spouse dies or remarries before 55 years of age; or the date the benefits of the participant terminates. the benefits of the former spouse shall commence on the date the participant would qualify on the basis of his or her creditable service for benefits under this subchapter (other than a disability annuity) or the date the disability annuity begins, whichever is later, and the amount of benefits of the former spouse shall be calculated on the basis of benefits for which the participant would otherwise so qualify. Benefits under this section shall be treated the same as an annuity under section 4054(a)(7) of this title for purposes of section 4046(h) of this title or any comparable provision of law. Benefits under this section shall not be payable unless appropriate written application is provided to the Secretary, complete with any supporting documentation which the Secretary may by regulation require, within 30 months after December 22, 1987 . The Secretary may waive the 30-month application requirement under this subparagraph in any case in which the Secretary determines that the circumstances so warrant. Upon approval of an application provided under subparagraph (A), the appropriate benefits shall be payable to the former spouse with respect to all periods before such approval during which the former spouse was entitled to such benefits under this section, but in no event shall benefits be payable under this section with respect to any period before December 22, 1987 . with respect to a participant or former participant subject to this part, the annuity of the participant or former participant; and with respect to a participant or former participant subject to part II, the benefits of the participant or former participant under that part. Nothing in this section shall be construed to impair, reduce, or otherwise affect the annuity or the entitlement to an annuity of a participant or former participant under this subchapter. the former employee retired from the Civil Service Retirement and Disability System on a date before his employing agency could legally participate in the Foreign Service Retirement and Disability System; and the marriage included at least five years during which the employee was assigned overseas.