individual population census tracts into larger geographic areas, and (C) shall treat any violation of this paragraph as a violation of section 6103. (5) Definitions Any term used in this subsection which is also used in subchapter Z of chapter 1 of the Internal Revenue Code of 1986 shall have the meaning given such term under such subchapter. III Modification of rules for investments in qualified opportunity funds 301. Extension of deferral and investment period (a) In general Subparagraph (B) of sections 1400Z–2(a)(2) and 1400Z–2(b)(1) of the Internal Revenue Code of 1986 is amended by striking December 31, 2026 and inserting December 31, 2028 . (b) Effective date The amendment made by this section shall apply to amounts invested after December 22, 2017. 302. Modification of definition of qualified opportunity fund (a) In general Section 1400Z–2(d)(1) of the Internal Revenue Code of 1986 is amended to read as follows: (1) In general The term qualified opportunity fund means— (A) any qualified feeder fund, or (B) any other investment vehicle if— (i) such investment vehicle is organized as a corporation or a partnership for the purpose of investing in qualified opportunity zone property (other than another qualified opportunity fund), and (ii) such investment vehicle holds at least 90 percent of its assets in qualified opportunity zone property, determined by the average of the percentage of qualified opportunity zone property held in the fund as measured— (I) on the last day of the first 6-month period of the taxable year of the fund, and (II) on the last day of the taxable year of the fund. . (b) Qualified feeder fund Section 1400Z–2(d) of such Code is amended by adding at the end the following new paragraph: (4) Qualified feeder fund The term qualified feeder fund means any investment vehicle that invests in a qualified opportunity fund if— (A) such investment vehicle is organized as a domestic partnership for the purpose of investing in one more corporations or partnerships described in paragraph (1)(B), (B)