Taxation in the United States is a complex system which may involve payment to at least four different levels of government and many methods of taxation. United States taxation includes local government, possibly including one or more of municipal, township, district and county governments. It also includes regional entities such as school and utility, and transit districts as well as including state and federal government.

Taxation may be carried out by the Fed (Federal Reserves.) The U.S. tax code is known as the Internal Revenue Code of 1986 (title 26 of the United States Code). The Code's complexity generally arises from two factors: the use of the tax code for purposes other than raising revenue, and the feedback process of amending the code.

While its main intent is to provide revenue for the federal government, the tax code is frequently used for public policy reasons i.e., to achieve social, economic, and political goals. For example, the tax law provides a deduction for mortgage interest on primary residences in order to encourage home ownership.