August 16, 1954, as heretofore, hereby, or hereafter amended, may be cited as the "Internal Revenue Code of 1986". (b) References in Laws, Etc. – Except when inappropriate, any reference in any law, Executive order, or other document – (1) to the Internal Revenue Code of 1954 shall include a reference to the Internal Revenue Code of 1986, and (2) to the Internal Revenue Code of 1986 shall include a reference to the provisions of law formerly known as the Internal Revenue Code of 1954. Thus, the 1954 Code was renamed the Internal Revenue Code of 1986 by section 2 of the Tax Reform Act of 1986. The 1986 Act contained substantial amendments, but no formal re-codification. That is, the 1986 Code retained most of the same lettering and numbering of subtitles, chapters, subchapters, parts, subparts, sections, etc. The 1986 Code, as amended from time to time (and still published as title 26 of the United States Code), retains the basic structure of the 1954 Code. Commonly misunderstood special definitions Employee Wages Many others can be found at https://www.law.cornell.edu/uscode/text/26/3401 Individual and corporate income tax Section 1 of the Internal Revenue Code imposes the federal income tax on the taxable income of U.S. citizens and residents, and of estates and trusts. The corporate income tax is imposed by Internal Revenue Code section 11. Organization The organization of the Internal Revenue Code, as enacted in hundreds of Public Laws passed by the U.S. Congress since 1954, is identical to the organization of the Internal Revenue Code separately published as Title 26 of the U.S. Code. For example, section 162(e)(4)(B)(ii) (26 U.S.C. ) would be as follows: Title 26: Internal Revenue Code Subtitle A: Income Taxes : Normal Taxes and Surtaxes : Computation of Taxable Income Part VI: Itemized Deductions for Individuals and Corporations : Trade or business expenses Subsection (e): Denial of deduction for certain lobbying and political expenditures Paragraph (4): Other special rules Sub-paragraph (B)): De minimis exception Clause (ii): In-house expenditures The Internal Revenue Code is topically organized and generally referred to by section number (sections 1 through 9834). Some topics are short (e.g., tax rates) and some quite long (e.g., pension & benefit plans). Key IRC Topics By Section: Subtitles A. Income Taxes (sections 1 through 1564)As a further example, here are the chapters of this subtitle: (sections 1 through 1400U3) (sections 1401 through 1403) (sections 1441 through 1464)