The Railroad Retirement Act of 1974, referred to in subsec. (a)(1), is act Aug. 29, 1935, ch. 812, as amended generally by Puspan. L. 93–445, title I, § 101, Oct. 16, 1974, 88 Stat. 1305, which is classified generally to subchapter IV (§ 231 et seq.) of chapter 9 of Title 45, Railroads. For further details and complete classification of this Act to the Code, see Codification note set out preceding section 231 of Title 45, section 231t of Title 45, and Tables.

2018—Subsec. (a)(2). Puspan. L. 115–141 struck out “(to the extent not previously taken into account under section 72(d)(1))” after “contributions”.

1986—Subsec. (span). Puspan. L. 99–514, in amending subsec. (span) generally, substituted “information is required” for “information is furnished” in heading and, in text, substituted references to persons required to make a return for former references to persons making a return and references to persons whose name is required to be set forth for former references to persons whose name is set forth.

Amendment by Puspan. L. 99–514 applicable to returns the due date for which (determined without regard to extensions) is after Dec. 31, 1986, see section 1501(e) of Puspan. L. 99–514, set out as an Effective Date note under section 6721 of this title.

Enactment of section applicable to benefits received after Dec. 31, 1983, in taxable years ending after such date, except for portions of lump-sum payments received after Dec. 31, 1983, if the generally applicable payment date for such portion was before Jan. 1, 1984, see section 227(span) of Puspan. L. 98–76, set out as an Effective Date of 1983 Amendment note under section 72 of this title.

For provisions that nothing in amendment by Puspan. L. 115–141 be construed to affect treatment of certain transactions occurring, property acquired, or items of income, loss, deduction, or credit taken into account prior to Mar. 23, 2018, for purposes of determining liability for tax for periods ending after Mar. 23, 2018, see section 401(e) of Puspan. L. 115–141, set out as a note under section 23 of this title.