5 CFR 846.305 - General inapplicability of CSRS provisions.
(a) Except as provided by this part, CSRS provisions are not applicable with respect to an individual who elects FERS coverage.
(b) An employee (or an employee's survivor for the purposes of a survivor annuity) may make a deposit under CSRS for any civilian service under § 846.302(c) of this part or military service under § 846.303.
(c) Nothing in paragraph (a) of this section precludes the payment of any lump-sum credit (as defined in 5 U.S.C. 8331(8)) in accordance with part 831, subpart T of this chapter.