The Civil Service Retirement Act of 1920 (P.L. 66-215) established a pension system for federal employees in the executive branch of government. Coverage under the Civil Service Retirement System (CSRS) was extended to Congress in January 1942 by P.L. 77-411. That law was repealed just two months later in response to adverse public opinion. In 1946, P.L. 79-601 again extended CSRS coverage to Congress, at the option of Members, with higher contributions and greater benefits than those applicable to regular federal employees. In its report on that legislation, the Special Committee on the Organization of Congress stated that a retirement plan for Congress would contribute to independence of thought and action, [be] an inducement for retirement for those of retiring age or with other infirmities, [and] bring into the legislative service a larger number of younger Members with fresh energy and new viewpoints concerning the economic, social, and political problems of the Nation. The Social Security Amendments of 1983 ( P.L. 98-21 ) required all federal employees hired in 1984 or later to participate in Social Security. These amendments also required all Members of Congress to participate in Social Security as of January 1, 1984, regardless of when they first entered Congress. Requiring federal workers to participate in both CSRS and Social Security would have duplicated some benefits and would have resulted in employee payroll deductions for the two programs that would exceed 13% of pay. After mandating Social Security coverage of new federal employees beginning in 1984, Congress directed the development of a new retirement plan for federal workers with Social Security coverage as its foundation. The result of this effort was the Federal Employees' Retirement System Act of 1986 ( P.L. 99-335 ). The Federal Employees' Retirement System (FERS) went into effect in 1987, and employees first hired in 1984 or later were automatically enrolled in this plan. Employees who had been in the federal government before 1984 were given the option to remain in CSRS—without Social Security coverage—or to switch to FERS. The options for Members of Congress differed from those available to other federal employees because the 1983 amendments required all Members of Congress to participate in Social Security. Members first elected in 1984 or later were given the option to enroll in FERS as well as being covered by Social Security, or to be covered only by Social Security. Members who had been in Congress before 1984 could elect to stay in CSRS in addition to being covered by Social Security; to elect coverage under an "offset plan" that integrates CSRS and Social Security; to elect coverage under FERS in addition to being covered by Social Security; or to be covered only by Social Security. Because of the uncertain tenure of congressional service, FERS was originally designed, as CSRS had been, to provide a larger benefit for each year of service to Members of Congress and congressional staff than to most other federal employees. Prior to P.L. 112-96 , all Members of Congress also became eligible for retirement annuities at an earlier age and with fewer years of service than most other federal employees. However, all Members of Congress and congressional staff also paid a higher percentage of salary for their retirement benefits than do most other federal employees before P.L. 112-96 was enacted. The Middle Class Tax Relief and Job Creation Act of 2012 ( P.L. 112-96 ) made two significant changes to the retirement benefits of Members of Congress who are first covered by FERS after December 31, 2012. First, P.L. 112-96 decreased the FERS benefit accrual rate (used in the FERS pension calculation) for Members first covered by FERS (or reelected with less than five years of FERS service) after December 31, 2012, to be the same as regular FERS employees. Therefore, the larger benefit per year of service is no longer available to Members (or congressional employees) first covered by FERS after December 31, 2012. Second, P.L. 112-96 also increased the FERS employee contributions by 1.8 percentage points for Members of Congress first covered by FERS (or reelected with less than five years of FERS service) after December 31, 2012. Therefore, Members newly covered by FERS in 2013 are required to contribute 3.1% of pay to FERS. Subsequent to P.L. 112-96 , the Bipartisan Budget Act of 2013 ( P.L. 113-67 ) further increased the FERS employee contributions by an additional 1.3 percentage points for all individuals, including Members of Congress, first covered by FERS (or rehired/reelected with less than five years of FERS service) after December 31, 2013. Therefore, under P.L. 113-67 , Members of Congress and other federal employees first covered by FERS beginning in 2014 are required to contribute 4.4% of pay to FERS. Thus, for individuals first covered by FERS after December 31, 2012, there is no longer a larger employee contribution under FERS required for Members and congressional employees in comparison with regular FERS employees; all of these groups contribute 3.1% of pay toward their FERS annuity if first covered in 2013 or 4.4% of pay if first covered by FERS after 2013. Members of Congress first elected after December 31, 2012, however, remain eligible for retirement annuities under FERS at earlier ages and with fewer years of service than most other federal employees. There were 611 retired Members of Congress receiving federal pensions based fully or in part on their congressional service as of October 1, 2016. Of this number, 335 had retired under CSRS and 276 had retired under FERS. Members who had retired under CSRS had completed, on average, 23.5 years of civilian federal service. Their average annual CSRS annuity in 2016 was $74,028. Those who had retired under FERS had completed, on average, 15.8 years of civilian federal service. Their average retirement annuity in 2016 (not including Social Security) was $41,076. The average age of retired Members of Congress receiving retirement annuities in 2016 was 76 for those who had retired under CSRS and 73 for those who had retired under FERS. Members of Congress who were first elected before 1984 may be covered under one of four retirement plans: Dual Coverage. This is full coverage by both CSRS and Social Security. CSRS Offset. This is coverage by CSRS and Social Security, but with CSRS contributions and benefits reduced ("offset") by the amount of Social Security contributions and benefits. FERS. This is composed of the FERS basic annuity, Social Security, and the Thrift Savings Plan (TSP). Social Security Only. This occurs if the Member declines other coverage. Members and other federal employees who were covered under CSRS had the opportunity to switch to FERS during two six-month "open seasons" in 1987 and 1998. In 1987, less than 5% of eligible federal employees switched from CSRS to FERS, and in 1998 less than 1% of eligible employees switched. Members of Congress who were first elected in 1984 or later are covered automatically by the Federal Employees' Retirement System. Prior to the Legislative Branch Appropriations Act, 2004 ( P.L. 108-83 ), all Members could decline this coverage. Effective with passage of P.L. 108-83 , however, Representatives entering office on or after September 30, 2003, may not elect to be excluded from such coverage. All Senators, regardless of date, and those Representatives serving as Members prior to September 30, 2003, continue to be able to decline this coverage. FERS is composed of three elements: 1. Social Security; 2. the FERS basic annuity , a monthly pension based on years of service and the average of the three highest consecutive years of basic pay; and 3. the Thrift Savings Plan , into which participants can deposit up to a maximum of $18,500 in 2018 (participants who are at least age 50 in 2018 can make an additional "catch-up" contribution of up to $6,000). Their employing agency matches employee contributions up to 5% of pay. Members who enter Congress with at least five years of previous federal employment covered by CSRS can choose to participate in the CSRS Offset Plan rather than FERS. Members become vested in (legally entitled to) a pension benefit under CSRS or FERS after five years of service. The age and service requirements for retirement eligibility are determined by the plan under which a Member is covered at the time of retirement, regardless of whether he or she has previous service covered under a different plan. Depending on a Member's age and years of service, a pension can be taken immediately upon retirement or only on a deferred basis. Likewise, the Member's age and years of service, as well as the starting date of the annuity, will determine whether he or she is eligible for a full pension or a reduced pension. Four retirement scenarios are possible for Members covered by CSRS or the CSRS Offset Plan. Retirement with an immediate, full pension is available to Members aged 60 or older with 10 years of service in Congress, or aged 62 with 5 years of civilian federal service, including service in Congress. Retirement with an immediate, reduced pension is available to Members aged 55 to 59 with at least 30 years of service. It is also allowed if the Member separates for a reason other than resignation or expulsion after having completed 25 years of service, or after reaching the age of 50 and with 20 years of service, or after having served in nine Congresses. Retirement with a deferred, full pension is available if the Member leaves Congress before reaching the minimum age required to receive an immediate, unreduced pension and delays receipt until reaching the age at which full benefits are paid.