The Internal Revenue Service (IRS) is ready to help Americans pay their taxes, whether they want to or not. A bureau in the Department of the Treasury, the IRS is responsible for tax collection and tax law enforcement in its numerous forms. The agency collects 93% of the revenues that fund the US federal government. With an annual budget of about $13.6 billion, the IRS strives to fulfill its mission by helping taxpayers understand their obligations and by consistently and fairly enforcing tax laws. The agency is structured into four primary divisions: Wage and Investment, Large and International Business, Small Business and Self-Employed, and Tax-Exempt and Government Entities.
The IRS traces its origins to the Civil War when President Lincoln created the position of Commissioner of Internal Revenue and enacted an income tax to pay war expenses. Repealed in 1872, reinstated in 1894, ruled unconstitutional in 1895, the IRS became a permanent fixture in 1913 with the ratification of the 16th Amendment.