Until the amount reaches the filing requirement for the IRA to file its own return for unrelated business taxable income (UBTI). I'd have to look up if that includes gain on sale of units. Buying PTPs in an IRA is sort of like buying municipal bonds in an IRA -- you lose out on a lot of the tax benefits.
It does include income on sale of units. The ones I've seen usually come from the client's broker who is sending a nervous letter to explain why the non taxable IRA suddenly has to pay a tax.
