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Federal Tax Research Guide

A guide to conducting federal tax research.

Primary Sources of Law

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.

Substantial Authority

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:

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