Duties & Functions

Internal Revenue Service

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The Internal Revenue Service (IRS) is responsible for determining, assessing, and collecting internal revenue in the United States. This revenue consists of personal and corporate income taxes, excise, estate, and gift taxes, as well as employment taxes for the nation's Social Security system.

The Bureau of Internal Revenue was established on July 1, 1862, to collect new income taxes, money which was used to pay for the Civil War. Although the income tax was declared unconstitutional by the Supreme Court in 1895, the national income tax was reinstated in 1913. The Bureau of Internal Revenue was responsible for enforcement of the Prohibition amendment in the 1920's. The Bureau of Internal Revenue was reorganized in 1953 and renamed the Internal Revenue Service. It remains the largest of Treasury's bureaus.