Except as provided by this part, CSRS provisions are not applicable with respect to an individual who elects FERS coverage.
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.
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.