plus the net operating loss carrybacks to such year, and (2) in the case of a taxable year beginning after December 31, 2020, the sum of— (A) the aggregate amount of net operating losses arising in taxable years beginning before January 1, 2018, carried to such taxable year, plus (B) the lesser of— (i) the aggregate amount of net operating losses arising in taxable years beginning after December 31, 2017, carried to such taxable year, or (ii) 80 percent of the excess (if any) of— (I) taxable income computed without regard to the deductions under this section and sections 199A and 250, over (II) the amount determined under subparagraph (A). . (2) Conforming amendments (A) Section 172(b)(2)(C) of such Code is amended to read as follows: (C) for taxable years beginning after December 31, 2020, be reduced by 20 percent of the excess (if any) described in subsection (a)(2)(B)(ii) for such taxable year. . (B) Section 172(d)(6)(C) of such Code is amended by striking subsection (a)(2) and inserting subsection (a)(2)(B)(ii)(I) . (C) Section 860E(a)(3)(B) of such Code is amended by striking all that follows for purposes of and inserting subsection (a)(2)(B)(ii)(I) and the second sentence of subsection (b)(2) of section 172. . (b) Modification of rules relating to carrybacks (1) In general Section 172(b)(1) of the Internal Revenue Code of 1986 is amended by adding at the end the following new subparagraph: (D) Special rule for losses arising in 2018, 2019, and 2020 (i) In general In the case of any net operating loss arising in a taxable year beginning after December 31, 2017, and before January 1, 2020— (I) such loss shall be a net operating loss carryback to each of the 5 taxable years preceding the taxable year of such loss, and (II) subparagraphs (B) and (C)(i) shall not apply. (ii) Special rules for REIT's For purposes of this subparagraph— (I) In general A net operating loss for a REIT year shall not be a net operating loss carryback to any taxable year preceding the taxable year of such loss. (II) Special rule In