You fix it by reporting the correct basis for the stock sold, not the $0 basis (I assume) reported by the broker.
Your correct per share basis is: (compensation created by the vesting) divided by (GROSS number of shares vesting)
Enter the 1099-B exactly as it reads 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. The correct basis is: (# of shares sold) x (per share basis for that lot).
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.)
