(a) Type of benefits. A former spouse who meets the eligibility requirements of §20.3 is entitled to survivor benefits equal to one of the following; whichever is applicable:

(1) 55 percent of the full annuity to which the principal was entitled on the commencement or recomputation date of the annuity in the case of a principal who dies while in receipt of a Foreign Service annuity computed under section 806, 808, 823, 824, or 855 of the Act of 5 U.S.C. 8415;

(2) 55 percent of the annuity to which the principal was entitled at death in the case of a principal who dies while in receipt of a Foreign Service annuity computed under 5 U.S.C. 8452;

(3) 55 percent of the full annuity to which the principal would have been entitled if he or she retired (or returned to retirement status) on the date of death computed—depending on the provision that would be used to compute an annuity for a surviving spouse of the principal—under section 806(a), 823, 824, or 855(b) of the Act of 5 U.S.C. 8415 and using the actual service of the principal, in the case of a principal who dies while in active service, including service on recall or reemployment while annuity is suspended or reduced; or,

(4) 55 percent of the full annuity computed under 5 U.S.C. 8413(b) that the principal could have elected to receive commencing on the date of death or, if later, commencing on the date the principal would have attained the minimum retirement age described in 5 U.S.C. 8412(h), in the case of a principal while entitled to a deferred annuity under 5 U.S.C. 8413(b), but before commencement of that annuity. A survivor annuity under this paragraph may not commence before the date the principal would have attained the minimum retirement age.

(b) Effect of election of alternate form annuity. If a principal elects an alternate form annuity under section 829 of the Act or 5 U.S.C. 8420a, survivor benefits for a former spouse under this section shall, nevertheless, be based on what the principal's annuity would have been had the principal not withdrawn retirement contributions in a lump sum.

(c) Reduction because of receipt of other survivor benefits. If a former spouse is in receipt of a survivor annuity based on an election by the principal under section 806(f) or 2109 of the Act, the survivor benefits for the former spouse under this section shall be reduced on the effective date by the amount of such elected survivor annuity.

(d) Commencement and Termination. Entitlement to survivor benefits under this section—

(1) Shall commence on the latter of—

(i) The date the principal dies;

(ii) December 22, 1987; and

(2) Shall terminate on the last day of the month before the former spouse dies or remarries before attaining age 55.