The Internal Revenue Service (IRS) is the revenue service of the United States federal government. The government agency is a bureau of the Department of the Treasury, and is under the immediate direction of the Commissioner of Internal Revenue. The IRS is responsible for collecting taxes and the administration of the Internal Revenue Code. It has also overseen various benefit programs, and enforces portions of the Affordable Care Act.
The first income tax was assessed in 1862 to raise funds for the American Civil War, with a rate of 3%. Today the IRS collects over $2.4 trillion each tax year. It processes around 234 million tax returns annually.