Short answers, pulled from the story.
The Internal Revenue Code of 1986 (IRC) is the domestic portion of federal statutory tax law in the United States, codified as Title 26 of the United States Code. It covers federal income taxes, payroll taxes, estate and gift taxes, and excise taxes, as well as procedure and administration. The Internal Revenue Service is its implementing agency.
The first document formally titled the Internal Revenue Code was enacted by Congress on the 10th of February 1939 and published as Part I of volume 53 of the United States Statutes at Large. Before that, tax statutes were codified as part of the broader United States Code beginning in 1926, and before 1874 U.S. statutes were not codified by subject matter at all.
Ward M. Hussey was the principal drafter of the Internal Revenue Code of 1954. The code was enacted on the 16th of August 1954 by the 83rd United States Congress under Chapter 736 and published in volume 68A of the United States Statutes at Large.
The Tax Reform Act of 1986 renamed the 1954 Code the Internal Revenue Code of 1986 via section 2 of that act. The 1986 Act included substantial amendments but no formal re-codification, so the lettering and numbering of subtitles, sections, and subparts established in 1954 remained unchanged.
The 1954 Code imposed a progressive income tax on individuals with 24 brackets, ranging from 20 percent at the lowest income levels to 91 percent on income above $200,000. The bracket covering income between $150,000 and $200,000 carried a 90 percent marginal rate.
Section 401, paragraph (k) of the Internal Revenue Code governs employer-sponsored retirement plans, the arrangement widely known as a 401(k). The related section 402A covers optional Roth treatment of elective deferrals, while section 408A covers Roth IRAs.