; and (2) by inserting after subsection (q) the following new subsection: (r) Individual retirement arrangement defined For purposes of this section and sections 72(t), 4973, 4974, and 6501(l), the term individual retirement arrangement means an individual retirement account described in section 408(a), an individual retirement annuity described in section 408(b), and a Roth IRA described in section 408A. . 6. Effective date (a) In general Subject to subsections (b) and (c), this Act and the amendments made by this Act shall take effect on the date of the enactment of this Act. (b) Transition provisions (1) Requests for waivers (A) In general Notwithstanding the amendments to section 4974(d) of the Internal Revenue Code of 1986 made by section 3(b)(2) of this Act, a taxpayer may, at any time before or during the transition period, file a written request for a waiver under section 4974(d) of such Code, as in effect on the day before the date of the enactment of this Act. The Secretary of the Treasury shall consider any such request as if the amendments made by section 3(b)(2) had not been made. (B) Transition period defined For purposes of this paragraph, the term transition period means the period beginning on the date of the enactment of this Act and ending on the date that is 1 year after such date of enactment. (2) Applicability to certain prior acts (A) In general Except as provided in paragraph (1), the amendments made by this Act shall apply to any determination of or affecting liability for taxes, interest, or penalties that is made on or after the date of the enactment of this Act, even if the conduct upon which the determination is based occurred before such date of enactment. (B) Calculation of correction window in certain cases In the case of an error that would have been eligible for correction under section 4973(i) or 4974(e) of the Internal Revenue Code of 1986 if tax had not been imposed under 4973(a) or 4974(a), as the case may be, of such Code before the date of the enactment of this Act, the