Some federal employees leave the government, withdraw their retirement contributions, and then return to work for the government. For that service to count in the calculation of an annuity or a survivor annuity, a redeposit with interest must be made (with an exception as described below).
A redeposit can be made in installments but must be made in full before the final adjudication of an annuity. Survivors of employees who die in service also can make a redeposit before the final adjudication of their annuity in order to capture service credit in that calculation (for survivors of retirees, the survivor annuity is based on the calculation that produced the retiree’s own benefit, which included credit for redeposit service as pertinent).
With one exception, anyone separating from service and receiving a refund of CSRS contributions must repay that money, plus any applicable interest, before the period of time covered by the refund can be credited in the computation of annuity benefits.
The exception is this: Instead of paying the redeposit, anyone who received a refund covering a period of service that ended before March 1, 1991 can choose to have their annuity actuarially reduced based on their age and the amount of redeposit, including interest, owed at the time of retirement.
FERS employees with CSRS service always have been allowed to make redeposits of withdrawn CSRS contributions to recapture credit for that time. However, until a 2009 change in law, if you withdrew FERS contributions, that time was forfeited and could not be recaptured. Since enactment of that law, FERS employees may make redeposits with interest to count that time in their benefit calculations.
If you are in FERS with a CSRS component and you received a refund covering a period of service that ended before March 1, 1991, to recapture that service time you have the choice of either making the redeposit for that service or having the CSRS component of your annuity actuarially reduced.