The IRS offers a withholding calculator, here: Tax Withholding Estimator.
You can use the tool to help estimate how to revise your W-4 (what your payroll department uses to withhold tax from your paycheck).
You can also double check your return to be sure you have not transposed any numbers or made an error in any of your entries. Printing out a pdf of your tax return is a good place to start. Here are the instructions to obtain a pdf: How do I get a PDF of my return?
