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Tax Research

Use this guide as an introduction to researching federal tax questions, for tax policy research and for finding IRS documents and other tax-related materials.

Regulation numbering

Numbering of regulations track the Internal Revenue Code (IRC) section to which the regulation relates and interprets. 

For example, in regulation  1.61-9(c) interprets section 61 of the IRC.

See:

Regulations explanation

The Federal Income Tax Regulations  are the official Treasury Department interpretation of the Internal Revenue Code and follow the numbering sequence of Internal Revenue Code sections.

Tax regulations are sometimes referred to as "Treasury Regulations (Treas. Reg.) and are promulgated by the I.R.S. and Dept. of Treasury. 

Generally, regulations are first published in proposed form in a Notice of Proposed Rulemaking (NPRM). After public input is fully considered through written comments and even a public hearing, a final regulation or a temporary regulation is published as a Treasury Decision (TD) in the Federal Register.

For explanations and finding the different stages of regulations, see boxes on this page for:

Final and Temporary Regulations Sources

Final (approved after the regulatory process) and temporary regulations are first published in the Federal Register and Internal Revenue Bulletin (IRB).  They are then codified in Title 26 of the Code of Federal Regulations (CFR). 

Temporary regulations are often issued soon after a major change in the law to provide guidance for the public and Internal Revenue Service employees with respect to procedural and computational matters. Temporary regulations are authoritative and have the same weight as final regulations.  ( IRM 4.10.7.2.3.3 ).

For the current version of a final or temporary regulation, check the Code of Federal Regulations (CFR).

Sources:

Proposed Regulations

Generally, regulations are first published in proposed form in a Notice of Proposed Rulemaking (NPRM). After public input is fully considered through written comments and even a public hearing, a final regulation or a temporary regulation is published.  Proposed regulations are published in the Federal Register (FR).

Preambles

Preambles are found in Treasury Decisions (those that are final regulations) which can be found in the Cumulative Bulletin and Internal Revenue Bulletin.

Abbreviations

Abbreviations key for frequently cited IRS (and other useful) documents (Bluebook format in italics):

  • acq or nonacq. - Notices of Acquiescence or Nonacquiescence
  • action on dec. also AOD - Actions on Decisions
  • ann - Announcements
  • CCA - Chief Counsel Advice
  • C.B. - Cumulative Bulletin
  • C.F.R. - Code of Federal Regulations
  • DO , also DLO - Delegation Order
  • FR, also Fed. Reg. - Federal Register
  • F.S.A.  -  Field Service Advice
  • Gen. Couns. Mem. also GCM - General Counsel Memoranda
  • I.R.B. - Internal Revenue Bulletin
  • I.R.C. - Internal Revenue Code: Title 26 of the United States Code
  • IRM - Internal Revenue Manual
  • NSAR - Non docketed Service Advice Review
  • Priv. Ltr. Rul. also PLR or LR - Private Letter Rulings
  • Prop. Treas. Reg. - Proposed Treasury Regulation
  • Rev. Proc. - Revenue Procedures
  • Rev. Rul. - Revenue Rulings
  • Stat. - Statutes at Large
  • T.D. - Treasury Decision (regulation with preamble)
  • Tech. Adv. Mem. also TAM, T.A. Memo. - Technical Advice Memoranda
  • T.C.M. - Tax Court Memorandum decisions
  • T.M.  also Tech. Mem. - Technical Memorandum (not the same as a TAM)
  • Treas. Reg. - Treasury Regulations: Title 26 of the Code of Federal Regulations