The IRS just redesigned the Form W-4 to make it easier for you to have your tax withholding match up with your tax liability. If you would like more than is needed for taxes withheld, you will get it back when you file your return. You won't earn interest on the overpayments, but remember that the goal with tax withholding is to make it ideal for one's life situation. Even if you don't have any income tax withheld, you may still get money back thanks to tax credits like the Earned Income Credit, the Additional Child Tax Credit, and American Opportunity Credit.