of the Opportunity Zone Reform Act . . 3. Maintenance of geographic boundaries of qualified opportunity zones Section 1400Z–1(e) of the Internal Revenue Code of 1986, as redesignated by section 2(a)(2), is amended by adding at the end the following new sentence: Such designation shall apply to the geographic area as in effect at the time such tract is designated without regard to whether adjustments are made to the boundaries of the census tract so designated. . 4. Modification of prohibition on certain types of trades or business as qualified opportunity zone businesses (a) In general Section 1400Z–2(d)(3)(A)(iii) of the Internal Revenue Code of 1986 is amended by striking in section 144(c)(6)(B) and inserting subsections (a)(8)(B) or (c)(6)(B) of section 144 or section 147(e) . (b) Effective date The amendment made by this section shall take effect on November 6, 2019. 5. Other modifications related to qualified opportunity funds (a) Application of qualified opportunity zone business rules to trades or businesses conducted by qualified opportunity zone funds (1) 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 any investment vehicle— (A) which is organized as a corporation or a partnership for the purpose of investing in qualified opportunity zone property (other than another qualified opportunity fund) that 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, and (B) any trade or business of which is a qualified opportunity zone business. . (2) Effective date The amendments made by this subsection shall take effect as if included in section 13823 of Public Law 115–97 . (b) Clarification of substantially all (1) In general