property described in subparagraph (B) or (C) of paragraph (2)), and (ii) property described in subparagraph (B) or (C) of paragraph (2) which is placed in service in 2020. . (4) The heading of section 168(k) is amended by striking Special allowance for certain property acquired after December 31, 2007, and before January 1, 2020 and inserting Full expensing of certain property . (5) Section 460(c)(6)(B)(ii) is amended by striking January 1, 2020 (January 1, 2021 in the case of property described in section 168(k)(2)(B)) and inserting January 1, 2023 (January 1, 2024 in the case of property described in section 168(k)(2)(B)) . (g) Effective date (1) In general Except at provided by paragraph (2), the amendments made by this section shall apply to property which— (A) is acquired after September 27, 2017, and (B) is placed in service after such date. For purposes of the preceding sentence, property shall not be treated as acquired after the date on which a written binding contract is entered into for such acquisition. (2) Specified plants The amendments made by subsection (f)(2) shall apply to specified plants planted or grafted after September 27, 2017. (3) Transition rule In the case of any taxpayer’s first taxable year ending after September 27, 2017, the taxpayer may elect (at such time and in such form and manner as the Secretary of the Treasury, or his designee, may provide) to apply section 168 of the Internal Revenue Code of 1986 without regard to the amendments made by this section. (4) Limitation on net operating loss carrybacks attributable to full expensing In the case of any taxable year which includes any portion of the period beginning on September 28, 2017, and ending on December 31, 2017, the amount of any net operating loss for such taxable year which may be treated as a net operating loss carryback (including any such carryback attributable to any specified liability loss under section 172(b)(1)(C), any corporate equity reduction interest loss under section 172(b)(1)(D), any eligible loss under