Decedents In the case of a decedent, amounts recognized under this section shall, if not properly includible in the gross income of the decedent, be includible in gross income as provided by section 691. (4) Regulations The Secretary shall prescribe such regulations as may be necessary or appropriate to carry out the purposes of this section, including— (A) rules for the certification of qualified opportunity funds for the purposes of this section, and (B) rules to prevent abuse. (f) Failure of qualified opportunity fund to maintain investment standard (1) In general If a qualified opportunity fund fails to meet the 90-percent requirement of subsection (c)(1), the qualified opportunity fund shall pay a penalty for each month it fails to meet the requirement in an amount equal to the product of— (A) the excess of— (i) the amount equal to 90 percent of its aggregate assets, over (ii) the aggregate amount of qualified opportunity zone property held by the fund, multiplied by (B) the underpayment rate established under section 6621(a)(2) for such month. (2) Special rule for partnerships In the case that the qualified opportunity fund is a partnership, the penalty imposed by paragraph (1) shall be taken into account proportionately as part of the distributive share of each partner of the partnership. (3) Reasonable cause exception No penalty shall be imposed under this subsection with respect to any failure if it is shown that such failure is due to reasonable cause. . (b) Basis adjustments Section 1016(a) is amended by striking and at the end of paragraph (36), by striking the period at the end of paragraph (37) and inserting , and , and by inserting after paragraph (37) the following: (38) to the extent provided in subsections (b)(2) and (c) of section 1400Z–2. . (c) Report to Congress The Secretary of the Treasury, or the Secretary’s delegate, shall submit a report to Congress on the opportunity zone incentives enacted by this section beginning 5 years after the date of enactment of this Act and annually