Modified environmental tax taxable income The term modified environmental tax taxable income has the meaning given to such term in section 59B(b). , and (iii) in subsection (g)(1)(A), by striking plus at the end of clause (ii), by redesignating clause (iii) as clause (iv), and by inserting after clause (ii) the following: (iii) the tax imposed by section 59B, plus . (H) Section 9507(b)(1) of such Code is amended by inserting 59B, before 4611 . (I) The table of parts for subchapter A of chapter 1 of such Code is amended by inserting after the item relating to part VII the following new item: Part VIII. Environmental tax . (c) Effective dates (1) Excise taxes The amendments made by subsection (a) shall take effect on the date of the enactment of this Act. (2) Income tax The amendments made by subsection (b) shall apply to taxable years beginning after the date of the enactment of this Act.