Social Security Introduction and Overview


Social Security is a self-financed program that provides monthly cash benefits to retired and disabled workers and their family members, and to the family members of deceased workers. The program is authorized under Title II of the Social Security Act and administered by the Social Security Administration (SSA). As of June 2011, there were 54.8 million Social Security beneficiaries. Of those, 38.1 million were retired workers and family members, 10.4 million were disability beneficiaries, and 6.3 million were survivors of deceased workers.[i]

Social Security is financed by payroll taxes paid by covered workers and their employers. In 2011, an estimated 156.9 million workers are covered by Social Security.[ii] Employees and employers each pay 6.2% of covered earnings up to an annual limit ($106,800 in 2011); self-employed individuals pay 12.4% of net self-employment income up to an annual limit ($106,800 in 2011).[iii] Self-employed persons may deduct one-half of their Social Security payroll taxes for federal income tax purposes.[iv] Social Security is also credited with tax revenues from the federal income taxes paid by some beneficiaries on a portion of their benefits.

Social Security income and outgo are accounted for in two separate trust funds authorized under Title II of the Social Security Act: the Federal Old-Age and Survivors Insurance (OASI) trust fund and the Federal Disability Insurance (DI) trust fund.[v] As the Managing Trustee of the Social Security trust funds, the Secretary of the Treasury is required by law to invest Social Security revenues in interest-bearing federal government securities (special issues) held by the trust funds.[vi] The revenues exchanged for the federal government securities are deposited into the general fund of the U.S. Treasury and are indistinguishable from revenues in the general fund that come from other sources. Funds needed to pay Social Security benefits and administrative expenses come from the redemption or sale of federal government securities held by the trust funds.[vii]

In 2010, the Social Security trust funds had total income of $781 billion, total expenditures of $713 billion and accumulated holdings of $2.6 trillion.[viii] Because the assets held by the trust funds are federal government securities, the trust fund balance ($2.6 trillion at the end of 2010) represents the amount of money owed to the Social Security trust funds by the general fund of the U.S. Treasury.

Origins and Brief History of Social Security

Title II of the original Social Security Act of 1935[ix] established a national plan designed to provide economic security for the nation’s workers. The system of Old-Age Insurance it created provided benefits to individuals who were aged 65 or older and who had “earned” retirement benefits through work in jobs covered by the system. Benefits were to be financed by a payroll tax paid by employees and employers on wages up to a base amount ($3,000 per year at the time). Monthly benefits were to be based on cumulative wages in covered jobs. The law related the amount of the benefit to the amount of a worker’s wages covered by the program, but the formula was weighted to give a greater return, on payroll taxes paid, to low-wage earners. Before the Old-Age Insurance program was in full operation, the Social Security Amendments of 1939[x] shifted the emphasis of Social Security from protection of the individual worker to protection of the family by extending monthly cash benefits to the dependents and survivors of workers. The program now provided Old-Age and Survivors Insurance (OASI).

During the decades that followed, changes to the Social Security program were mainly ones of expansion. Coverage of workers became nearly universal (the largest groups remaining outside the system today are state and local government employees who have not chosen to join the system and federal employees who were hired before 1984). In 1956, Congress established the Disability Insurance (DI) program.[xi] Over the years, there were increases in the payroll tax rate, which increased from 2.0% of pay (1.0% each for employees and employers) in the 1937-1949 period to its current level of 12.4%.[xii] In addition, there were increases in the amount of wages subject to the payroll tax (the taxable wage base), which increased from $3,000 in the 1937-1950 period to its current level of $106,800.[xiii] The types of individuals eligible for benefits were expanded over the years,[xiv] and benefit levels were increased periodically. In 1972, legislation provided that benefits would increase automatically each year by the same percentage as the cost-of-living (effective in 1975).[xv]

Beginning in the late 1970s, legislative action regarding Social Security became more concentrated on solving persistent financing problems. Legislation enacted in 1977 raised taxes and curtailed future benefit growth in an effort to shore up the system’s finances.[xvi] Still, in 1982, the OASI trust fund needed to borrow assets from the DI trust fund and the Medicare Hospital Insurance trust fund (borrowed amounts were fully repaid by 1986). Finally, in 1983, Congress passed additional major legislation that was projected to restore solvency to the Social Security system on average over the 75-year projection period. Current projections by the Social Security Board of Trustees show that the Social Security system has a long-range funding shortfall. These projections, and other factors, have focused attention on potential Social Security program changes in the future.

Social Security Benefits

Social Security provides monthly cash benefits to retired and disabled workers and to the family members of retired, disabled or deceased workers. To be eligible for a Social Security retired-worker benefit, a person generally needs a minimum of 40 earnings credits, or 10 years of Social Security-covered employment (among other requirements).[xvii] A worker’s initial monthly benefit (known as the primary insurance amount or PIA) is based on his or her career-average earnings (using the highest 35 years of earnings) and a progressive benefit formula designed to provide a higher replacement rate for lower-wage workers compared to higher-wage workers.[xviii] A person may claim Social Security retired-worker benefits as early as age 62, however, benefits claimed before the full retirement age (FRA) are reduced to take into account the longer expected period of benefit receipt. The FRA ranges from age 65 to age 67, depending on the person’s year of birth. If a person claims benefits after he or she attains the full retirement age, benefits are increased (up to age 70) to take into account the shorter expected period of benefit receipt. In addition to benefit adjustments based on early or delayed retirement, other adjustments may apply such as those based on simultaneous entitlement to more than one type of Social Security benefit.

For Social Security disability benefits, “disability” is defined as the inability to engage in substantial gainful activity by reason of a medically determinable physical or mental impairment expected to result in death or last at least 12 months. Generally, the worker must be unable to do any kind of work that exists in the national economy, taking into account age, education and work experience. As noted above, a worker generally needs a minimum of 40 quarters of coverage for a Social Security retired-worker benefit. A worker may qualify for Social Security disabled-worker benefits with fewer quarters of coverage, depending on the age at which the worker became disabled. However, a minimum of 6 quarters of coverage is needed. Similarly, while the worker’s 35 highest years of earnings are used to compute a retired-worker benefit, fewer years of earnings may be used to compute a disabled-worker benefit. A disabled worker’s benefit is not reduced for receipt before the full retirement age.

Benefits for the Worker’s Family Members

Social Security is sometimes viewed narrowly as a program that provides benefits to retired and disabled workers. However, about 21% of current Social Security beneficiaries are dependents and survivors of retired, disabled and deceased workers.[xix]

Social Security benefits are payable to the spouse, divorced spouse or child of a retired or disabled worker. Benefits are also payable to the widow(er), divorced widow(er), child or parent of a deceased worker. In addition, in the case of a deceased worker, benefits are payable to the mother or father of a deceased worker’s child when the child is under age 16 or disabled and entitled to a Social Security child’s benefit based on the worker’s record. Benefits payable to family members are equal to a specified percentage of the worker’s PIA, subject to a maximum family benefit amount. For example, the spouse of a retired worker may receive up to 50% of the retired worker’s PIA, and the widow(er) of a deceased worker may receive up to 100% of the deceased worker’s PIA. Benefits paid to family members may be subject to adjustments based on the person’s age at entitlement, receipt of his or her own Social Security retired-worker benefit and other factors.

Chapter Overview

This chapter of the Green Book includes a series of Congressional Research Service (CRS) Reports organized under the following general headings:

  • History of Social Security;
  • Social Security Financing and the Trust Funds;
  • Social Security Benefits and Eligibility;
  • Social Security Disability Insurance; and
  • Program Administration and Administrative Funding.

Readers should consult the reports listed under each of these headings for information and data related to these topics. A Tables and Figures section provides a list of the tables and figures included in the CRS reports, and includes additional tables and figures related to Social Security, followed by a Legislative History and Links to Additional Resources.

[i] SSA, Monthly Statistical Snapshot, June 2011, released July 2011, Table 2,

[ii] Currently, 93% of workers in paid employment or self employment are covered by Social Security. SSA, 2011 Social Security/SSI/Medicare Information, May 18, 2011,

[iii] In 2011, there is a temporary 2 percentage point reduction in the Social Security payroll tax rate for employees (from 6.2% to 4.2%) and the self-employed (from 12.4% to 10.4%). The annual limit on covered wages and net self-employment income subject to the Social Security payroll tax (the taxable wage base) is adjusted annually based on average wage growth, if a Social Security cost-of-living adjustment (COLA) is payable.

[iv] Self-employed individuals are required to pay Social Security payroll taxes if they have annual net earnings of $400 or more. Only 92.35% of net self-employment income (up to the annual limit) is taxable.

[v] The OASI and DI trust funds are referred to on a combined basis as the Social Security trust funds.

[vi] Social Security Act, Title II, §201(d).

[viii] In 2010, 82% of Social Security’s total income was from payroll taxes, 3% was from federal income taxes paid on benefits, and 15% was from interest earned on trust fund assets.

[ix] P.L. 271, 74th Congress.

[x] P.L. 379, 76th Congress.

[xi] The DI program was established by the Social Security Amendments of 1956 (P.L. 880, 84th Congress). The program became known as the Old-Age, Survivors, and Disability Insurance (OASDI) program, the formal name for Social Security.

[xii] Congress has increased the Social Security payroll tax rate many times over the program’s history. The payroll tax rate under current law (12.4%) was established by the Social Security Amendments of 1983 (P.L. 98-21). P.L. 98-21 increased the payroll tax rate gradually from 11.4% in 1984 to 12.4% in 1990.

[xiii] The most recent legislative change to the Social Security taxable wage base was in 1977. The Social Security Amendments of 1977 (P.L. 95-216) established ad-hoc increases in the taxable wage base for 1979, 1980 and 1981, followed by a return to automatic wage indexation for 1982 and subsequent years.

[xiv] For example, the Social Security Amendments of 1965 (P.L. 89-97) established benefits for divorced wives aged 62 or older.

[xv] The Social Security Amendments of 1972 (P.L. 92-603) established automatic annual cost-of-living adjustments (COLAs) for benefits already in payment. Social Security COLAs are based on inflation as measured by the Consumer Price Index for Urban Wage Earners and Clerical Workers (CPI-W) using a formula specified by law.

[xvi] See the Social Security Amendments of 1977 (P.L. 95-216).

[xvii] A worker may earn a maximum of 4 earnings credits (or quarters of coverage, QCs) per calendar year. In 2011, a worker obtains 1 QC for each $1,120 of covered earnings, up to a maximum of 4 QCs for earnings of $4,480 or more.

[xviii] The replacement rate is the ratio of a worker’s initial benefit to his or her pre-retirement earnings.

[xix] SSA, Monthly Statistical Snapshot, June 2011,