I read the following paragraph on Investopedia Web site:
When you hold MLP shares within a retirement account, such as a Roth IRA, this income—if it totals $1,000 or more—is considered unrelated business taxable income, or UBTI. That makes it subject to immediate tax, unlike most other investments you might hold in an IRA, where your earnings are usually tax-deferred or, in the case of Roth IRAs, tax-free.
https://www.investopedia.com/ask/answers/102714/can-i-own-master-limited-partnerships-mlp-my-roth-ir...
