Ninety-five percent of workers, or 135 million people, are covered by the system. In addition to workers in the U.S. and territories, the system covers work done by U.S. citizens and resident aliens outside of the U.S. who are:

• Employed by an American employer;
• Employed by an American affiliate who has elected coverage;
• Self-employed (in certain circumstances).

• Federal civilian employees hired before 1984;
• Railroad workers who are covered by the Railroad Retirement System;
• Some state and local government employees;
• Household and farm workers whose earning don't meet certain minimum requirements;
• Self-employed workers whose earnings are very low;
• Some children who work in family businesses;
• Some people who, for religious reasons, are granted exemptions.

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