Treasury Department - Internal Revenue Service

The Office of the Commissioner of Internal Revenue was established by an act of July 1, 1862 (26 U.S.C.A. § 7802). The Internal Revenue Service (IRS) is responsible for administering and enforcing the internal revenue laws and related statutes, except those relating to alcohol, tobacco, firearms, and explosives. Its mission is to collect the proper amount of tax revenue at the least cost to the public and in a manner that warrants the highest degree of public confidence in the service's integrity, efficiency, and fairness.

To achieve that purpose, the IRS seeks to achieve the highest possible degree of voluntary compliance with the tax laws and regulations. It advises the members of the public of their rights and responsibilities, determines the extent of compliance and the causes of noncompliance, administers and enforces the tax laws, and seeks more efficient ways of accomplishing its mission.

The IRS determines, assesses, and collects internal revenue taxes, determines PENSION plan qualifications and exempt organization status, and prepares and issues rulings and regulations to supplement the provisions of the INTERNAL REVENUE CODE.

The sources of most revenues collected are individual income tax, social insurance, and retirement taxes. Other major sources include the corporation income, excise, estate, and gift taxes.