Federal tax laws are created by Congress and are made available in Title 26 of the U.S. Code.
The Department of the Treasury is the executive department of the federal government responsible for implementing the tax laws. Treasury regulations are administrative laws issued by the Treasury Department.
The Internal Revenue Service (IRS),a bureau of the Treasury, issues numerous documents to interpret the Internal Revenue Code and to enforce tax laws.
Taxation & Economic Reform Library (HeinOnline) contains tax regulations, laws, and hundreds of legislative histories of tax laws dating back to the late 1700s. It allows you to search across decades of tax laws, thus tracing the development of a law back to its inception. The collection also contains legislative histories of laws pertaining to the history of economic reform, stock reform, stimulus plans and other economic regulations in the U.S.