How to Cite Internal Revenue Code Sections and Regulations

To cite a provision of the current Internal Revenue Code, write “I.R.C.” followed by the section symbol and number, with no year: I.R.C. § 61. To cite a Treasury Regulation, write “Treas. Reg.” followed by a prefix that identifies the type of tax, a decimal, and the Code section the regulation interprets: Treas. Reg. § 1.61-1. Those two formats cover most of what tax writers need, and the rules below fill in the rest of how to cite Internal Revenue Code sections and regulations correctly.

The Basic Citation Formats

The Internal Revenue Code is Title 26 of the United States Code. In tax-specific writing, the convention is to cite it as “I.R.C.” rather than “26 U.S.C.” A citation to the section defining gross income looks like this:

I.R.C. § 61.

Treasury Regulations are the Treasury Department’s official interpretation of the Code and are published in Title 26 of the Code of Federal Regulations. Tax practice still cites them as “Treas. Reg.” rather than by C.F.R. number.1Internal Revenue Service. Tax Code, Regulations and Official Guidance Every regulation number opens with a prefix identifying the type of tax, followed by a decimal and the Code section being interpreted:

  • 1 for income tax (Treas. Reg. § 1.61-1 interprets IRC § 61)
  • 20 for estate tax (Treas. Reg. § 20.2001-1 interprets IRC § 2001)
  • 25 for gift tax
  • 31 for employment tax
  • 301 for procedure and administration

Citing Subdivisions and Multiple Sections

Code sections are subdivided in a fixed hierarchy that your citation should follow exactly:2U.S. Tax Court. Opinion Citation and Style Manual

  • Section: § 401
  • Subsection: (a)
  • Paragraph: (9)
  • Subparagraph: (B)
  • Clause: (i)
  • Subclause: (II)

A full pinpoint looks like I.R.C. § 263A(h)(3)(D)(ii)(I). Regulations take the same kind of trailing subdivisions: Treas. Reg. § 1.162-1(a)(1).

When you cite more than one section, double the section symbol. Use an en dash for a consecutive range and commas for non-consecutive sections:3The Tax Lawyer Citation & Style Manual. Statutes – Internal Revenue Code

  • I.R.C. §§ 55–59.
  • I.R.C. §§ 1, 11.
  • I.R.C. §§ 117(d), 127(c).

When to Include a Year

A common mistake is adding a year parenthetical like “(2024)” to a Code citation. Under both The Tax Lawyer Citation & Style Manual and the Bluebook’s own rule for the current Code, that is wrong.3The Tax Lawyer Citation & Style Manual. Statutes – Internal Revenue Code The current Code takes no year.

The year is only needed when you are citing a prior version of the Code, meaning the Internal Revenue Code of 1954 or the Internal Revenue Code of 1939:

I.R.C. § 341 (1954).
I.R.C. § 212 (1939).

I.R.C. or 26 U.S.C.?

Because the Code is Title 26, “26 U.S.C. § 61” is technically correct. The U.S. Tax Court treats either form as acceptable under Bluebook Rule 12.9.1, provided you use one consistently.2U.S. Tax Court. Opinion Citation and Style Manual In a general brief that also cites many other titles of the U.S. Code, “26 U.S.C.” can read more naturally. In tax-focused writing, “I.R.C.” is standard.

One small structural point worth knowing: section headings, chapter groupings, and “see” cross-references in the Code carry no legal weight. Section 7806 says so directly, so do not cite a heading as if it were operative text.4Office of the Law Revision Counsel. 26 U.S. Code 7806 – Construction of Title

Amended or Repealed Provisions

If the version of a section you are discussing is not the version in force today, your citation has to say so. Add the year of the compilation containing the language you mean, plus a parenthetical explaining the change:

I.R.C. § 402(k) (2025) (as amended in 2025 by Pub. L. No. 118-273).
I.R.C. § 402(k)(5) (2020) (prior to the 2025 amendment).

Without that parenthetical, readers will assume you mean the current text.

Proposed and Temporary Regulations

Not every Treasury Regulation is final. Proposed regulations are open for comment and not yet binding; temporary regulations have legal force but expire. Each has its own citation form:2U.S. Tax Court. Opinion Citation and Style Manual

  • Proposed: Prop. Treas. Reg. § 1.162-1
  • Temporary: Temp. Treas. Reg. § 1.67-1T(a)

Temporary regulations carry a “T” appended to the section number, as in 1.67-1T. When you introduce a temporary regulation in the body of a sentence for the first time, spell it out (“Temporary Treasury Regulation § 1.67-1T(a) provides that …”); after that the abbreviation is fine.

Regulation Preambles

The preamble to a Treasury Regulation, which explains the Treasury’s reasoning, is published in the Federal Register rather than the C.F.R. Cite it by Federal Register volume and page:

90 Fed. Reg. 57928.

Revenue Rulings, Procedures, and Other IRS Guidance

Revenue Rulings and Revenue Procedures appear in the Internal Revenue Bulletin (I.R.B.) and, for anything before 2009, in the Cumulative Bulletin (C.B.). Publication of the C.B. stopped in 2008, so guidance from 2009 onward is cited to the I.R.B. The format is the same for both:

Rev. Rul. 2004-52, 2004-1 C.B. 973.
Rev. Proc. 2013-34, 2013-43 I.R.B. 397.

To pinpoint a section inside the document, add the section number after the document number and a page range after the starting page:2U.S. Tax Court. Opinion Citation and Style Manual

Rev. Proc. 2013-34, § 4.01, 2013-43 I.R.B. 397, 399–400.

IRS Notices and Announcements follow the same structure:5Internal Revenue Service Office of Chief Counsel. Citation Form in Counsel Documents

Notice 2011-4, 2011-2 I.R.B. 282.
Ann. 2011-1, 2011-2 I.R.B. 304.

Private Letter Rulings and Technical Advice Memoranda are cited by a seven-digit number, in which the first two digits are the year, the next two the week, and the final three a sequence number:

P.L.R. 8210019.
T.A.M. 9643001.

One caveat that belongs in your text whenever you cite one: a PLR or TAM applies only to the taxpayer who requested it and cannot be relied on as precedent by anyone else.6Internal Revenue Service. TEB Private Letter Ruling – Some Basic Concepts

Short Form Citations

After a full citation, later references can shorten. For Code sections, drop “I.R.C.” and use the section symbol alone: § 61. Keep enough of the subdivision to stay unambiguous: § 1(a). In a document that cites other bodies of law, keep “I.R.C.” in the short form so readers do not have to guess which code you mean.

For Treasury Regulations, the short form usually keeps “Treas. Reg.” and the full regulation number: Treas. Reg. § 1.162-1. Where context makes the source obvious, § 1.162-1 is enough.

For I.R.B. guidance, drop the volume and page after the first citation. A repeat reference needs only the document number and, if needed, the section: Rev. Proc. 2013-34, § 4.01.2U.S. Tax Court. Opinion Citation and Style Manual “Id.” works when the citation immediately follows the same source, with a fresh pinpoint if you have moved within it: Id. § 4.03(2), 2013-43 I.R.B. at 400.