The interest paid in the voluntary contribution retirement savings program available to CSRS (but not FERS) employees will rise to 2.125 percent in calendar year 2018 from 1.875 percent in 2017. That rate also applies as the interest rate for required deposits and redeposits into the retirement fund to get credit for service for which no contributions were taken or for which refunds were received at a break in service, as well payments as to capture credit toward federal retirement for military service time, for those eligible.