For new folks that don't know where to find it, here's the dates for this year's k-1.
Enterprise Products Partners, L.P. (EPD) expects to complete the mailing of the Schedule K-1s for tax year 2012, to unitholders, by Thursday, March 28, 2013. The 2012 K-1s are scheduled to be available online by noon on Friday, March 22, 2013.
Electronic K-1 delivery is a new option available for 2012 K-1s. To ensure electronic delivery, of a 2012 K-1, unitholders must register by March 15, 2013.
it's the same time period every year, give or take a week, you are obviously new, so there is no excuse, just the way it is. If you don't like it, I'll be happy to buy your units from you for what your cost basis is!
The reciprocal agreement of 15% withholding only applies to dividends. Not MLP distributions. You need to file a US tax return and in turn take the credit for taxes paid to the US in your home country.
If you are a US taxpayer with Canadian (for example) tax withheld, the US allows a tax credit for some or or all of that money on US income taxes. All if the amount is small (under $300 or $600 for married joint return), and for larger amounts, the credit amount is computed based on factors. Canada usually just keeps that money, although you could file a non-resident income tax return and maybe pay less. For smaller investors, that is too much work for the gain.
Maybe your tax system has a similar foreign tax credit for you.