regarding treatment as change in method of accounting In the case of any taxpayer which (as of the date of the enactment of this Act) had adopted a method of accounting provided by section 174 of the Internal Revenue Code of 1986 (as in effect prior to the amendments made by this section) for the taxpayer’s first taxable year beginning after December 31, 2021, and elects the application of this paragraph— (A) the amendments made by this section shall be treated as a change in method of accounting for purposes of section 481 of such Code, (B) such change shall be treated as initiated by the taxpayer for the taxpayer’s immediately succeeding taxable year, (C) such change shall be treated as made with the consent of the Secretary, (D) such change shall be applied on a modified cut-off basis, taking into account for purposes of section 481(a) of such Code only the domestic research or experimental expenditures (as defined in section 174A(b) of such Code (as added by this section) and determined by applying the rules of section 174A(e) of such Code) paid or incurred in the taxpayer’s first taxable year beginning after December 31, 2021, and not allowed as a deduction in such taxable year, and (E) in the case of a taxpayer which elects the application of this subparagraph, the amount of such change (as determined under subparagraph (D)) shall be taken into account ratably over the 2-taxable-year period beginning with the taxable year referred to in subparagraph (B). (3) Election regarding 10-year writeoff (A) In general Except as otherwise provided by the Secretary, an eligible taxpayer which files, during the 1-year period beginning on the date of the enactment of this Act, an amended income tax return for the taxable year described in subparagraph (B)(ii) may elect the application of section 59(e) of the Internal Revenue Code of 1986 with respect to qualified expenditures described in section 59(e)(2)(B) of such Code (as amended by subsection (c)(3)) with respect to such taxable year. Such election shall be filed