Technically, the distribution is 100% ROC until your basis reaches zero. However, the MLP may have net operating earning from operations which are passed through to you via the K1 and are taxable as ordinary income (Schedule E). MLPs can also generate Portfolio income (interest, cap gains, etc) which are also passed on and taxable to the the partners at their respective tax rates.
When someone says "The distributions are 75% tax deferred", what they really mean is the operating earnings are approximately equal to 25% of the distributions. K-1s are issued in March and thats when you'll know for sure
Take a look at ALSK, Alaska Communications systems. Price has decreased with the rest of the market; dividend is now approx. 9.3%, all qualified dividends (15% max). I have loaded up on this one. If you are ready to risk currence exchange look at ATPWF, Atlantic Power Corp., a Canadian Powr trust. Toronto exhange sumbol ATP-UN.TO, web site, atlanticpowercoporation.com Dividend is currently about 12% after adjusting for Canadian tax and currency exchange. If commodities recover the Canadian dollar will regain strength and you will get an additinal boost in dividend and share price. here's the best part; they constantly increase the dividend. none of the dividends are qualified-put this one in your IRA or ROTH.