FYI: For those of you who received PSX shares in the spinoff and who have those shares in a Scottrade account, then Scottrade has automatically calculated the cost basis of the PSX shares. I suspect that other brokerages have done something similar. You don't have to calculate the cost basis of your COP/PSX shares, it's already been done for you. You can check your Scottrade account for the basis, whether or not you sold your PSX shares already.
1. Login to Scottrade 2. Select "My Account" 3. Select "Gain/Loss & Tax Center" link in the left menu 4. Scroll over "Gain/Loss Reports" a. If you have already sold your PSX select "Current Year Realized Gain/Loss" b. If you haven't sold your PSX select "Unrealized Gain Loss"