www.irs.gov/pub/irs-pdf/p505.pdf
IRS Publication 505 covers tax withholding and the information on Form W-4 that an employer will use to determine the amount of tax to withhold. The website also covers information on how employees should check their withholding to ensure that enough tax is withheld.
www.irs.gov/individuals/article/0,,id=96196,00.html
The purpose of this website is to help employees ensure that they do not have too much or too little income tax withheld from their pay. You may use the results of this program to help you complete a new Form W-4.
