When you receive an RSU, you don't have any immediate tax liability. You only have to pay taxes when your RSU vests and you receive an actual payout of stock shares. At that point, you have to report income based on the fair market value of the stock. The fair market value of the stock becomes part of your wages for the year and should have been reported on your W-2 form at tax time. RSUs are considered income, so your employer must withhold taxes. If your employer withholds too much or too little, consider submitting a new Form W-4 to adjust. RSUs appear in Box 14 of your W-2. I hope this points you somewhat in the right direction.