This may be a dumb place to ask this but... Am I correct in understanding that you dont pay interest on tax so long as you pay it by the due date at the beginning of the year? If you dont have your company take any taxes out of your pay check on your W-4 can you look at your taxes like an interest free loan that you have to pay back in a year? I would think you could wire that money to a savings account and earn interest on it. Is there something Im missing? Im getting ready to change jobs and want to fill out my W-4 the most financially beneficial way.