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Tax Research


United States Code
The United States Code is the codification by subject matter of the laws of the United States.  It is divided into fifty subject titles.  There have been three major tax codifications: the Internal Revenue Codes of 1939, 1954, and 1986.  The current Internal Revenue Code can be found in Title 26 of the U.S. Code.

The U.S. Code can be accessed through the following resources:

United States Statutes at Large
The Statutes at Large is the permanent collection of all laws and resolutions enacted during each session of Congress, prepared and published by the Office of the Federal Register.  Laws are published in order of the date of their enactment.  Also published are concurrent resolutions, proclamations by the President, proposed and ratified amendments to the Constitution, and reorganization plans.

The Statutes at Large can be accessed through the following resources:


Code of Federal Regulations
The Code of Federal Regulations (CFR) is the codification of the general and permanent rules published in the Federal Register by the executive departments and agencies of the federal government.  Current Treasury Regulations are found in Title 26 of the CFR.

The CFR can be accessed through the following resources:

  • Official CFR - (1996-current) 
  • Unofficial but most current CFR - (current)  
  • Westlaw (current, Westlaw password required) 
  • Lexis (current, Lexis password required) 

IRS Publications
IRS Publications vary in importance. Those published in the Internal Revenue Bulletin, most importantly Treasury Regulations, Revenue Rulings, and Revenue Procedures, can be cited as authority.   The Internal Revenue Bulletin also includes IRS notices, IRS news releases, and acquiescence or non- acquiescence in court decisions.  It can be accessed on the IRS website.

The other IRS publications listed here can be used as “substantial authority” to avoid a penalty under I.R.C. § 6662(b)(2). See 26 C.F.R. § 1.6662-4(d)(3)(iii). See the Table of IRS Materials, in the IRS Materials tabs of this guide, for information on where to find these primary sources.

  • Private Letter Rulings and Technical Advice Memoranda
  • Actions on Decisions and General Counsel Memoranda
  • Internal Revenue Service information or press releases; and notices, announcements and other administrative pronouncements published by the Service in the Internal Revenue Bulletin.

Court Decisions

Tax Court
The Tax Court has two kinds of decisions: Regular Opinions and Memo Opinions

Regular Opinions are those opinions that the chief judge has determined contain novel or important decisions.  They are officially published in the United States Tax Court Reports.  

  • All Tax Court opinions since September of 1995 are available on the Tax Court website.  
  • United States Tax Court Reports are available on HeinOnline’s U.S. Federal Agency Documents, Decisions, and Appeals database (available on campus and remotely with ASURITE) and on Westlaw (Westlaw password required). 
  • Before 1942, when the Tax Court was called the Board of Tax Appeals, opinions were published in the Board of Tax Appeal Reports.  Board of Tax Appeal Reports are available in HeinOnline’s U.S. Federal Agency Documents, Decisions, and Appeals database (available on campus or remotely with ASURITE) and on Westlaw (Westlaw password required).

Memo Opinions are those opinions not designated as “Regular,” and historically were not published officially.  Both Regular and Memo Opinions are available through the following resources:

U.S. District Court
Tax opinions, along with other federal district court opinions, are published in West’s Federal Supplement (since 1932).  Cases before 1932 are in the Federal Reporter.  Cases relating to taxation in the federal district courts can be searched on Westlaw (Westlaw password required) and Lexis (Lexis password required).

U.S. Court of Appeals and U.S. Supreme Court
West’s Federal Claims Reporter includes opinions from the Court of Appeals from the federal circuit and the Supreme Court. Cases relating to taxation in the federal courts of appeals and U.S. Supreme Court can be searched on Westlaw (Westlaw password required) and Lexis (Lexis password required).