90 percent of the assets of a qualified opportunity fund must be tangible property within an opportunity zone;. Qualified opportunity funds must self-certify as such with the IRS;. Qualified opportunity funds must measure their asset percentage six months after their election and at the end of the year, using the average to determine whether they qualify for the 90-percent test;. Qualified opportunity funds must continue to measure their asset percentage annually; and. Specifically, if a qualified opportunity fund makes an investment in a partnership or corporation that has an active trade or business in the opportunity zone, the proposed regulations provide that such lower tier “Qualified opportunity zone business” can provide much-needed relief not available to a qualified opportunity fund that invests directly in tangible property in an opportunity zone. Such a structure only requires such a qualified opportunity zone business to hold 70% of its assets in tangible property in the opportunity zone. The proposed regulations provide for a “Working capital safe harbor” that could allow a qualified opportunity zone business to draw up a written working capital plan and deploy the cash it receives from the qualified opportunity fund over a period of 31 months.