I agree with nexchap's answer. The instructions on my Sales Schedule don't say "whether to add or subtract the value they provide". They say:
"Column 6: This amount is the sum (emphasis added) of Columns 4 & 5 (Purchase Price and Cumulative Adjustments) and represents your estimated outside basis...in the disposed partnership interest."
The key word is "sum". Find the sum by adding the string of signed numbers. For example, with Initial Basis= $2000 and Adjustment= $-596 you will have: +2000 plus {-596} equals +1404. Technically speaking, your adding a negative number, not subtracting. I used words instead of + and = since Turbotax thought the expression was an account number (LOL).
My Sales Schedule had this calculation and the Final Adjusted Basis ("outside basis") on it. Your's may too. This is the basis you report to the IRS. Your initial purchase price is history. If your final basis is negative, see my answer below on how to handle it. Good luck!
