(a) An individual retiring under this part is not entitled to elect to receive an alternative form of annuity under 5 U.S.C. 8420a,even.

(b) Notwithstanding any other provision of this part, an annuity payable under this part will be computed under 5 U.S.C. 8415 if it commences or is reinstated under § 844.405 (b) or (c) of this part on or after:

(1) The annuitant has satisfied the age and service requirements for retirement under 5 U.S.C. 8412 (a) through (f); or

(2) The annuitant has reached age 62.