The Social Security Administration's continuous work history sample.

In 1939, the original Social Security Act was amended to require that eligibility for benefits and payment amounts would be determined based on quarters of coverage (employment) and annual wages. These amendments required the Social Security Administration (SSA) to develop a recordkeeping system that collected quarterly wage and salary amounts for workers covered by the Act. The Continuous Work History Sample (CWHS) evolved from the early production of information from this employment data base. Through the years, the CWHS has adapted to changes in Social Security programs and linkages were developed to employer and benefit data bases. The CWHS is a major source of Social Security program statistics and workforce data. Tabulations and microdata files from the CWHS data bases are regularly used by SSA staff in making revenue estimates, evaluating legislative proposals, and responding to informational inquiries. Today, the CWHS data in aggregated form are used at various levels of government outside of SSA for special analytic and research needs. In the past, special versions of the CWHS microdata files were made available to researchers under strict confidentiality restraints and with signed agreements on the specific conditions of use. However, certain confidentiality and disclosure issues raised in the interpretation of the Tax Reform Act of 1976 have prevented any recent releases of the CWHS to non-SSA researchers.