on any income and/or capital gains attributable to the leveraged portion of the investment;
It should be noted, as an alternative to borrowing, that the IRA can purchase the property with other parties, all of who pay cash. When this is done, there is no UDFI and there are no issues associated with the financing.
Conclusion
In summary, the tax laws (1) require that the investments in an IRA not benefit the IRA owner or other "disqualified persons" and (2) prevent "self-dealing" between the IRA and the IRA owner or other disqualified persons. However, by properly structuring an IRA investment in real estate, an IRA can obtain the benefits of real estate investment in a manner that complies with applicable tax laws.