You do need to report the sale of the 109 shares but if you use the correct basis to report the sale you won't "pay tax for this 109 shares again" though if the stock has appreciated from the 2015 vesting date you will have a gain to report. Of course if the price of the stock has declined from the 2015 vesting date you will report a loss.
Your per share basis for the stock is:
(compensation created by the vesting as reported to you on the W-2) divided by (GROSS number of shares that vested)
So look at your W-2 for the compensation amount and divide that by 200. Take that per share basis you just figured out and multiply that by 109. That's the basis for the sale.
Enter the 1099-B exactly as it reads, incorrect basis and all, and then click the blue "I'll enter additional info on my own" button. On the next page enter the correct basis in the "Corrected cost basis" box.
Tom Young
(SINCE THE DEVELOPERS CHANGE THE SECURITY SALE INTERVIEW EVERY SINGLE YEAR I'LL NOTE THAT THIS ANSWER'S DIRECTIONS ON HOW TO CORRECT THE BASIS FOR THE SALE PERTAINS TO THE 2016 INCOME TAX YEAR. I'M SURE THAT THE INTERVIEW WILL CHANGE IN THE YEARS AFTER THAT.)
