I'm not a "Tax Expert", but the thing that initially tripped me up on RSUs and ESPP shares is that the basis price reported on the 1099-B is usually 0 making the final sale pure profit as though the initial tax was never applied on the W-2. You have to go through and apply the adjusted base price values that are generally supplied in a report from your brokerage that identifies each batch of RSU or ESPP shares and the base prices for each when the tax was applied and paid in your W-2. Once, that's done, the gain/loss numbers will be more sane and you'll only be taxed on the increase in share value since the purchase date where the initial taxes were applied.
