Skip to Main Content

Federal Income Tax Guide: Regulations & Guidance

Regulations and Official Tax Guidance

Administrative Sources: Regulations and Other Official Tax Guidance

The Internal Revenue Service issues several different kinds of documents and publications to offer guidance on complying with the Internal Revenue Code.  Understanding IRS Guidance - A Brief Primer offers a brief look at the most common forms of guidance listed below. 


Regulations may be issued as Proposed, Temporary, or Final Regulations.

Proposed regulations are published in the Federal Register, giving interested parties an opportunity to make written or oral comments before they become final. A proposed regulation includes the abbreviation REG in its citation: REG-116641-01.

Temporary regulations are often issued simultaneously with proposed regulations to give taxpayers immediate guidance concerning a new provision of the law, and carry the same weight as final regulations. A temporary regulation includes a T in its citation: Treas. Reg. § 1.152-4T.

Final regulations have no special identifier: Treas. Reg. § 1.152-1, are promulgated by Treasury Decisions, and published in Title 26 of the Code of Federal Regulations.

Regulations are numbered in the same manner as the Code sections to which they relate, preceded by a numerical prefix indicating which tax is involved. The most common prefixes include:

    1. = Income Tax (e.g., Treas. Reg. § 1.862-1)

  20. = Estate Tax (e.g., Treas. Reg. § 20.2107-1)

  25. = Gift Tax (e.g., Treas. Reg. § 25.2702-4)

  31. = Employment Tax (e.g., Treas. Reg. § 31.3406(a)-1)

301. = Procedure and Administration (e.g., Treas. Reg. § 301.6335-1)


Regulations Governing Practice Before the Internal Revenue Service, (Circular 230), are printed in Title 31, Code of Federal Regulations, Part 10, and contain rules and ethics in tax practice.

      Revenue Rulings

Revenue Rulings are official IRS interpretation of the tax law as it applies to a specific fact situation, often with examples.

Revenue rulings are numbered chronologically and have two segments separated by a hyphen; the first segment indicates the year, and the second indicates the ruling number for that year. Beginning in 2000, the IRS began using all four digits to indicate the year (e.g., Rev. Rul. 90-28; Rev. Rul. 2002-28).

Revenue Rulings are published in the Internal Revenue Bulletin.  Cumulative Bulletins are available in our print and HeinOnline collections.  *Please note: the print version of the Internal Revenue Bulletin (IRB), ceased with the Aug. 6, 2012 issue (v. 2012-32); and the print version of the Cumulative Bulletin (CB) ceased in December 2008 (v. 2008-2).

Revenue Procedures

Official statements on the Service internal practice and procedure in the administration of the tax laws. These are numbered in the same way as Revenue Rulings (e.g., Rev. Proc. 99-2; Rev. Proc. 2002-2).

Revenue Procedures are also published in the Internal Revenue Bulletin.

Written Determinations

Determinations include Private Letter Rulings (L.T.R./P.L.R.), Technical Advice Memoranda (T.A.M.), and Chief Counsel Advice (C.C.A.) These documents are taxpayer or issue-specific determinations, and while they may be useful in determining the Service position on certain issues, they cannot be used or cited as precedent pursuant to 26 USC § 6110(k)(3).

- Private Letter Rulings are taxpayer-specific rulings written by the Service National Office in response to requests by taxpayers. Letter Rulings have a nine-digit numbering system beginning with the year, followed by the week and the number of the ruling for that week. For example, L.T.R. 200418053 refers to the 53rd letter ruling issued in the 18th week of the year 2004.

- Technical Advice Memoranda, published and numbered with letter rulings, are also written by the Service National Office when requested by the Service district officers.

- Chief Counsel Advice are prepared by the Office of Chief Counsel and issued to field or service center employees.


MARQCAT - Search library

Eckstein Law Library Map