FERS has been the Senate's retirement system since January 1, 1987, while CSRS applies only for those senators who were in the Senate from December 31, 1986, and prior. As it is for federal employees, congressional retirement is funded through taxes and the participants' contributions. Under FERS, senators contribute 1.3% of their salary into the FERS retirement plan and pay 6.2% of their salary in Social Security taxes.