The Internal Revenue Service (IRS) is the revenue service for the United States federal government, which is responsible for collecting U.S. federal taxes and administering the Internal Revenue Code, the main body of the federal statutory tax law. It is an agency of the Department of the Treasury and led by the commissioner of Internal Revenue, who is appointed to a five-year term by the president of the United States. The duties of the IRS include providing tax assistance to taxpayers; pursuing and resolving instances of erroneous or fraudulent tax filings; and overseeing various benefits programs, including the Affordable Care Act.
The IRS originates from the Office of Commissioner of Internal Revenue, a federal office created in 1862 to assess the nation's first income tax to fund the American Civil War. The temporary measure funded over a fifth of the Union's war expenses before being allowed to expire a decade later. In 1913, the Sixteenth Amendment to the U.S. Constitution was ratified, authorizing Congress to impose a tax on income and leading to the creation of the Bureau of Internal Revenue. In 1953, the agency was renamed the Internal Revenue Service, and in subsequent decades underwent numerous reforms and reorganizations, most significantly in the 1990s.