. (3) Section 246(b)(1) is amended by inserting 199A, before 243(a)(1) . (4) Section 613(a) is amended by inserting and without the deduction under section 199A after and without the deduction under section 199 . (5) Section 613A(d)(1) is amended by redesignating subparagraphs (C), (D), and (E) as subparagraphs (D), (E), and (F), respectively, and by inserting after subparagraph (B), the following new subparagraph: (C) any deduction allowable under section 199A, . (6) The table of sections for part VI of subchapter B of chapter 1 is amended by inserting at the end the following new item: Sec. 199A. Qualified business income. . (d) Effective date The amendments made by this section shall apply to taxable years beginning after December 31, 2017. 11012. Limitation on losses for taxpayers other than corporations (a) In general Section 461 is amended by adding at the end the following new subsection: (l) Limitation on excess business losses of noncorporate taxpayers (1) Limitation In the case of taxable year of a taxpayer other than a corporation beginning after December 31, 2017, and before January 1, 2026— (A) subsection (j) (relating to limitation on excess farm losses of certain taxpayers) shall not apply, and (B) any excess business loss of the taxpayer for the taxable year shall not be allowed. (2) Disallowed loss carryover Any loss which is disallowed under paragraph (1) shall be treated as a net operating loss carryover to the following taxable year under section 172. (3) Excess business loss For purposes of this subsection— (A) In general The term excess business loss means the excess (if any) of— (i) the aggregate deductions of the taxpayer for the taxable year which are attributable to trades or businesses of such taxpayer (determined without regard to whether or not such deductions are disallowed for such taxable year under paragraph (1)), over (ii) the sum of— (I) the aggregate gross income or gain of such taxpayer for the taxable year which is attributable to such trades or businesses, plus (II)