"Am I being double taxed?"
If you simply enter the 1099-B as it reads you will be. Brokers are not required to report anything but your "out of pocket" cost for stock acquired via an RSU and since your out of pocket cost is $0 mindlessly entering the 1099-B and filing the resulting income tax return would result in double income reporting: reporting the compensation income associated with the vesting on your W-2 and then overstating your short term capital gain based on the 1099-B.
Each "vesting" constitutes a "lot". The compensation created by the vesting is calculated as:
(GROSS number of shares vesting) x (per share "fair market value" used by your employer for that lot)
Accordingly your per share basis for any particular lot is the same as that per share fair market value figure.
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.)
