The interest paid in the voluntary contribution retirement savings program available to CSRS (but not FERS) employees will fall to 1.875 percent from 2 percent in 2016. 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.