Federal tax law begins with the Internal Revenue Code (IRC), enacted by Congress in Title 26 of the United States Code (26 U.S.C.).
The Internal Revenue Code (or IRC; more formally, the Internal Revenue Code of 1986, as amended) is the main body of domestic statutory tax law of the United States organized topically, including laws covering the income tax (see Income tax in the United States), payroll taxes, gift taxes, estate taxes and statutory excise taxes. The Internal Revenue Code is published as Title 26 of the United States Code (USC), and is also known as the internal revenue title. Its governing authority is the Internal Revenue Service.
Subtitle A—Income Taxes Subtitle B—Estate and Gift Taxes Subtitle C—Employment Taxes Subtitle D—Miscellaneous Excise Taxes Subtitle E—Alcohol, Tobacco, and Certain Other Excise Taxes Subtitle F—Procedure and Administration Subtitle G—The Joint Committee on Taxation Subtitle H—Financing of Presidential Election Campaigns Subtitle I—Trust Fund Code Subtitle J—Coal Industry Health Benefits Subtitle K—Group Health Plan Requirements
The Internal Revenue Code (or IRC; more formally, the Internal Revenue Code of 1986, as amended) is the main body of domestic statutory tax law of the United States organized topically, including laws covering the income tax (see Income tax in the United States), payroll taxes, gift taxes, estate taxes and statutory excise taxes. The Internal Revenue Code is published as Title 26 of the United States Code (USC), and is also known as the internal revenue title. Its governing authority is the Internal Revenue Service.
Source :
http://www.law.cornell.edu/uscode/html/uscode26/usc_sup_01_26.html
http://en.wikipedia.org/wiki/Internal_Revenue_Code
http://www.irs.gov/taxpros/article/0,,id=98137,00.html#irc