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The Internal Revenue Code (IRC) Title 26 of the U.S.C. contains nearly all federal tax law. The current version of the Code is the Internal Revenue code of 1986, as amended.

There have been three major enactments of the IRC: The 1939 Code, the 1954 Code, and the 1986 Code. Prior to the 1939 Code, federal tax laws were individual Revenue Acts.

The Code is organized topically into subtitles, chapters, subchapters, and parts. There are a lot of cross-references, so it is often useful to read the table of contents to the IRC or to a subchapter in order to get an overview of the structure of a topic. (Note that this is a good strategy for all statutory research, although it is particularly useful here).

General definitions, which apply throughout the code, are contained in section 7701. You should also check each subtitle, chapter etc. for definitions specific to those particular sections.

Subtitles:

Commonly-Researched Subchapters of Subtitle A (Income Taxes):