any 30-month period beginning after the date of acquisition of such property, additions to basis with respect to such property in the hands of the taxpayer exceed an amount equal to the adjusted basis of such property at the beginning of such 30-month period in the hands of the taxpayer. (D) Treatment of related parties For purposes of subparagraph (A)(ii), the rules of subparagraph (A) of section 179(d)(2) shall be applied using the relationship described in subsection (e)(2) in lieu of the relationship described in such subparagraph. (5) Qualified gigabit opportunity fund The term qualified gigabit opportunity fund means any investment vehicle organized as a corporation or a partnership for the purpose of investing in qualified gigabit opportunity zone property (other than another qualified opportunity fund) that holds at least 90 percent of its assets in qualified opportunity zone property, determined— (A) on the last day of the first 6-month period of the taxable year of the fund, and (B) on the last day of the taxable year of the fund. (6) Qualified gigabit opportunity zone business (A) In general The term qualified gigabit opportunity zone business means a trade or business— (i) in which substantially all of the tangible property owned or leased by the taxpayer is qualified gigabit opportunity zone business property, (ii) which satisfies the requirements of paragraphs (2), (4), and (8) of section 1397C(b), and (iii) which is not described in section 144(c)(6)(B). (B) Special rule For purposes of subparagraph (A), tangible property that ceases to be a qualified gigabit opportunity zone business property shall continue to be treated as a qualified gigabit opportunity zone business property for the lesser of— (i) 5 years after the date on which such tangible property ceases to be so qualified, or (ii) the date on which such tangible property is no longer held by the qualified gigabit opportunity zone business. (e) Applicable rules (1) In general For purposes of this section and except as otherwise provided in