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Tax Law Research Guide: Introduction


The primary sources of Federal tax law are:

  • The Internal Revenue Code, which is Title 26 of the United States Code;
  • Decisions of the United States Tax Court, district courts, Court of Federal Claims, federal circuit courts, and the United States Supreme Court;
  • Treasury Regulations, located in Title 26 of the Code of Federal Regulations; 
  • Internal Revenue Service guidance published in the Internal Revenue Bulletin, including Revenue Rulings, Revenue Procedures, Notices, and Announcements; and
  • Other Internal Revenue Service material, including Private Letter Rulings and Technical Advice Memoranda.

It is important for the researcher to keep in mind the provisions of Treas. Reg. § 1.6662-4(d)(3) regarding "Substantial Authority." The types of materials that are substantial authority for the purposes of this Regulation include:

  • The Internal Revenue Code
  • Proposed, temporary, and final regulations
  • Tax treaties and applicable regulations
  • Court cases
  • Congressional intent as reflected in committee reports
  • General explanations on tax legislation by the Joint Committee on Taxation ("The Blue Book")
  • Private Letter Rulings issued after October 31, 1976
  • Actions on decisions
  • General Counsel Memoranda
  • IRS Press Releases
  • Notices, announcements, and other administrative pronouncements
    published by the IRS in the Internal Revenue Bulletin


Use Bluebook and A UNIFORM SYSTEM OF FEDERAL TAX CITATIONS at the same time.


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Jootaek Lee
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