5 CFR § 842.705 - Alternative forms of annuities available.
(a) An employee or Member who is eligible to make an election under § 842.703 may elect to receive his or her lump-sum credit, excluding interest, plus an annuity computed in accordance with sections 8415 and 8421 of title 5, United States Code, for which they qualify (including any reduction for survivor benefits) and reduced under § 842.706.
(b) A retired employee or Member who elected an alternative form of annuity is subject to all provisions of subchapters II and IV of chapter 84 of title 5, United States Code, as would otherwise apply to a retired employee or Member who did not elect an alternative form of annuity. An individual who has elected an alternative form of annuity is not eligible to apply for disability annuity under subchapter V of such chapter.