5 CFR § 839.603
Can I later change my election?
November 4, 2020
Your election is irrevocable once your employer or OPM processes it. If you do not make a timely election, the resulting coverage (see §839.602) is also irrevocable.
Your election is irrevocable once your employer or OPM processes it. If you do not make a timely election, the resulting coverage (see §839.602) is also irrevocable.