Here is the answer given by someone else- in case you need

This might seem to be taxed at your regular income rate but the tax paid is based on the results of the "Qualified Dividends and Capital Gain Tax Worksheet" that is used to enter the amount of tax you pay. This worksheet is on page 38 of the 1040 instructions and is part of the overall instructions for figuring the amount of tax on 1040 line 44 that begin on page 36. It is this worksheet that parses out the amount(s) to be taxed at the different rates (ordinary income, 5% capital gain, 15% capital gain). Depending on other factors particular situation, other worksheets may be involved as well.

Disclaimer:
This is based on my own limited understanding and cursory reading of the instructions. I am not a tax professional and you should not base any tax decision on this advice; consult the IRS or a tax professional for more definitive advice if you are unsure. You may also want to consult those in the tax forum: