If you hold a Limited Partnership or LLC in your IRA then any Unrelated Business Income in excess of $1,000 is taxable (even though it is in an IRA). It is not reported on your tax return but on a 990-T form. (The custodian of your IRA is required to file the form for you but you must submit the K-1 form(s) to them - ask the custodian about this).
Unrelated Business Income is reported as code "V" in box 20 on the K-1 form.
Also see pub 598.
http://www.irs.gov/publications/p598/ch01.html
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
