investment is made does not exceed the applicable amount. (C) Applicable amount For purposes of this paragraph, the term applicable amount means, with respect to any taxable year in which a qualified investment is made— (i) in the case of an individual not described in clause (ii), $100,000 (as increased for the taxable year by the cost-of-living adjustment under subsection (e)(2)), and (ii) in the case of an individual who is a married individual filing a joint return or who is a head of household (as defined in section 2(b)) for the taxable year, an amount equal to 2 times the amount in effect under clause (i) for the taxable year. (D) Rules for determining average taxable income For purposes of this paragraph— (i) a married individual filing a separate return of tax for any taxable year shall include the taxable income of their spouse in computing the individual's average taxable income for any period unless the Secretary determines that the spouse's information is not available to the individual, and (ii) the Secretary shall prescribe rules for the determination of average taxable income in cases where the individual had different filing statuses for the 3 taxable years described in subparagraph (B). (e) Definitions and special rules For purposes of this section— (1) Related persons A person shall be treated as related to another person if the person bears a relationship to such other person described in section 267(b), except that section 267(b) shall be applied by substituting 5 percent for 50 percent each place it appears. (2) Cost-of-Living adjustments In the case of any taxable year beginning after 2020, the $10,000 amount under subsection (b)(2)(A)(i) and the $100,000 amount under subsection (d)(5)(C)(i) shall each be increased by an amount equal to— (A) such dollar amount, multiplied by (B) the cost-of-living adjustment under section 1(f)(3) for the calendar year in which the taxable year begins, determined by substituting 2019 for 2016 in subparagraph (A)(ii) thereof. If any increase in such $10,000