Federal government’s sources of revenue

• In 2007 the federal government collected $2.5 trillion, an amount equal to 18.8 percent of GDP. Federal revenue has ranged from 14.4 to 20.9 percent of GDP over the past five decades, averaging 18.0 percent.
• The individual income tax has been the largest single source of federal revenue since 1950, averaging just over 8 percent of GDP.
• Payroll taxes swelled following the creation of Medicare in 1965. Taxes for Medicare, combined with periodic increases in Social Security taxes, caused payroll tax revenue to grow from 1.6 percent of GDP in 1950 to more than 6 percent since 1990. Payroll taxes also include railroad retirement, unemployment insurance, and federal workers’ pension contributions.
• Revenue from the corporate income tax fell from between 5 and 6 percent of GDP in the early 1950s to 2.7 percent of GDP in 2007.
• Excise taxes fell steadily throughout the same period, from nearly 3 percent of GDP in 1950 to 0.6 percent in recent years.
• The remaining sources of revenue have fluctuated less, together claiming between 0.5 and 1.0 percent of GDP since 1950 and standing near the bottom of that range in 2007.
• Changes in the shares of the various taxes in total federal revenue reflect these historical shifts. The individual income tax has consistently provided nearly half of total federal revenue since 1950, while other revenue sources have waxed and waned. Excise taxes brought in 19 percent of total revenue in 1950 but only about 3 percent in recent years. The share of revenue coming from the corporate income tax dropped from about one-third in the early 1950s to less than one-sixth in 2007. In contrast, payroll taxes provided more than one-third of revenue in 2007, compared with just one-tenth in the early 1950s.

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