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).