Search the Internal Revenue Code (Title 26 of the United States Code) through the Office of the Law Revision Counsel or Cornell Law School. Please note that these versions of the tax code may not reflect the latest amendments.
The links to the sections below are from the Internal Revenue Code posted on the Cornell Law School's website.
The Treasury Regulations interpreting the Internal Revenue Code can be accessed through the Government Printing Office. See under Title 26, Internal Revenue for the latest version available.