- irs.gov
IRS Withholding Calculator

If you are an employee, the Withholding Calculator can help you determine whether you need to give your employer a new Form W-4, Employee's Withholding Allowance Certificate to avoid having too much or too little Federal income tax withheld from your pay. You can use your results from the calculator to help fill out the form.
CAUTION: This Withholding Calculator works for most taxpayers. However, if you owe self-employment tax, alternative minimum tax, or certain Other Taxes; you should use the instructions in Pub 505, Tax Withholding and Estimated Tax.
Tips For Using This Program
Have your most recent pay stubs handy.
Have your most recent income tax return handy.
Estimate values if necessary, remembering that the results will be no more accurate than the input you provide.
Ready to start? Make sure Java scripting is enabled before using this application.
To Change Your Withholding:
Use your results from this calculator to help you complete a new Form W-4, Employee's Withholding Allowance Certificate.
Submit the completed Form to your employer as soon as possible.