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Federal Income Tax Legal Research Guide: Introduction

A research guide to bibliographic sources for federal tax research on how and where to find tax documentation. Call numbers are specific to locations within the Brooklyn Law School Library.


Federal tax authority consists of primary and secondary sources.  The government's legislative, administrative and judicial branches produce primary authority in the form of statutes, treaties, regulations, rulings and judicial decisions.  The tax researcher needs to understand the functions of these governmental bodies and the sources of law which they promulgate. 

Secondary sources of tax authority consist of unofficial publications, for example, treatises, tax services, and periodical literature.  Secondary tax materials help to locate, explain, analyze and interpret primary tax resources.  Understanding these basic concepts help make the task of finding print and electronic resources that publish these materials a systematic and methodical procedure that will facilitate the tax research process.

This research guide takes a bibliographic approach to federal tax research and explains how and where to find tax documentation.  Indicated call numbers are specific to items in the Brooklyn Law School Library at Brooklyn Law School located in the Main Collection in the cellar level unless indicated otherwise.

Tax Research Guides


Federal tax statutes are codified in Title 26 of the United States Code. Title 26 is commonly referred to as the Internal Revenue Code (IRC). The first IRC was passed in 1939. The IRC of 1939 was then comprehensively revised by, and replaced by, the IRC of 1954. The current version of the IRC is the IRC of 1986. The Tax Reform Act of 1986 substantively amended the IRC of 1954, so the statute was renamed the IRC of 1986.

Print Versions (Located on the Second Floor of the Library):

  • USC: KF 62 2006 A2
  • USCA:   KF 62 1927 W45
  • USCS: KF 62 1972 L38


 Online Versions:

  • Lexis:   Go to Title 26 of the United States Code Service (USCS) (type USCS in main search bar)
  • Westlaw Go to Title 26 of the United States Code Annotated (USCA) (type USCA in main search bar & click on USCA under Content Pages)


Free Online Sources: 

Citing to the US Code

Official v. Unofficial Versions of the Code

  • The United States Code (USC) is the official publication of the US Code. United States Code Annotated (USCA) and United States Code Service (USCS) are unofficial publications.  
    • The Bluebook prefers citations to the official federal code, the USC (Rule 12.3).
    • When citing to the unofficial versions (USCS & USCA), be sure to include the name of the publisher (e.g. West for the USCA, LexisNexis for the USCS) (Rule 12.3.1). Citations to the federal code, whether official or unofficial, do not require a date (Rule 12.3.2).   
  • Codified federal statutes enacted subsequent to the latest edition or supplement of the Code should be cited to an unofficial code. (Rule 12.2.1)

Date in Citation

Note that the date in a citation to the US Code, the USCA, or the USCS is the year of the code edition cited as it appears on the spine of the print volume or the title or copyright page, not the year a statute was enacted or last amended. The US Code is published every 6 years and an annual supplement is published each year in between.  The latest (21st) edition of the Bluebook no longer requires a date when citing to the federal code, whether official or unofficial. 


Citation to Supplements

  • When a statute is codified and published in a supplement, but has not yet been published in the official code, the year of the supplement should be included in the parenthetical. (Rule 12.3.1)  
  • Statutes that are split between the published code & a subsequent supplement (i.e. a statute that was amended) should cite to both dates (Rule 12.2.2)