Section 847.412 - Elections of FERS instead of CSRS(a) An employee who elects CSRS coverage under § 847.411(a) may, during the 6-month period beginning on the date the election under § 847.411(a) is filed with the employing agency, elect to become subject to FERS.(b) An election of FERS under this section is subject to the provisions of part 846 of this subchapter and takes effect on the first day of the first pay period after the employing agency receives the election.