Example as follows: Received an employer sponsored Restricted Stock Unit award on 06-01-15 for 106 shares. 41 shares were traded for taxes, remaining 65 were awarded to me. Then reported on a 1099-B for 2016, those 65 shares acquired on 06/01/15 and were sold on 05/25/2016, with net proceeds of $4,075.84. Since the 41 shares we already traded for taxes (~40%) at the time of grant, what is now owed on the $4,075.84? Is that 100% taxable as 2016 income? Short term capital gains?