Employees who have an opportunity to elect FERS coverage typically:
If you return to Federal employment after a break in service of more than 3 days, you may elect to transfer to FERS during the first 6 months of your reemployment. You are not required to elect FERS.
If you do not elect FERS, your retirement coverage will be CSRS or CSRS Offset. If you are eligible to elect FERS coverage, you will be notified by the Civilian Benefits Center at the time of your
eligibility. You will not have another chance to choose FERS coverage unless you leave Federal service for more than 3 days.