The box 19 info counts as a reduction in your basis in the partnership, at least until you reach zero basis. In other words, if you bought 100 shares at $40, your original basis is $4000. Each year you reduce that by the amount in Box 19 and use the adjusted basis as your cost when you sell the shares. If you'd owned the shares for 2 years and received $500 total from Box 19 and then sold the shares, your effective purchase price on Schedule D would be $3500, not $4000. It gets more complicated if your adjusted basis gets to zero. A good general set of instructions for filling out your US taxes from a partnership K-1 is http://www.irs.gov/pub/irs-pdf/i1065sk1.pdf.