The taxes withheld associated with the compensation created by the exercise of the option almost certainly is included on your W-2, just not disclosed to you like the income is. The cash raised from shares sold "for taxes" is handed back to the employer, who pays the government, and includes that amount in the W-2 withholding boxes. You can't claim those taxes again.
If you are thinking along these lines because you've noticed that you've reported the "gain" on the stock, (i.e., the "spread" between what you paid for the stock and what it was worth on that date), then that's because you are using the wrong basis. Your basis per share is the same "per share fair market value" the employer used to calculate the W-2 income, but brokers only report the out of pocket cost as basis. So if you enter the 1099-B exactly as it reads you report that income twice.
To correct that:
Using the spreadsheet-like "fill in the boxes" default TurboTax 1099-B entry form enter the 1099-B exactly as it reads. Tick the box next to "This sale involves an employee stock plan (including ESPP) or an uncommon situation." Click the blue "Start Now" button that shows up and then click the radio button next to "My 1099-B has info I know isn't right, or it has extra info I need to add." That will allow you to add the missing amount of basis and TurboTax will show all this correctly on Form 8949.
Tom Young
EDIT: SINCE THE SOFTWARE WRITERS AT TURBOTAX SEEM TO CHANGE THE INTERVIEW CONCERNING THE SALE OF SECURITIES EVERY YEAR, THE DESCRIPTIONS ABOVE CONCERNING THE TURBOTAX PROGRAM ARE ONLY APPLICABLE TO THE TURBOTAX PROGRAM FOR THE YEAR THE QUESTION WAS ASKED.
