Did you know the IRS has a withholding Calculator?
Go to https://apps.irs.gov/app/tax-withholding-estimator
Before You Begin
Gather the most recent pay statements for yourself, and if you are married, for your spouse too. Gather information for other sources of income you may have. Have your most recent income tax return handy. Use whole dollar amounts in the estimator.
The IRS encourages everyone to use the Tax Withholding Estimator to perform a “paycheck checkup.” This will help you make sure you have the right amount of tax withheld from your paycheck.
There are several reasons to check your withholding:
Checking your withholding can help protect against having too little tax withheld and facing an unexpected tax bill or penalty at tax time next year.
At the same time, you may prefer to have less tax withheld up front, so you receive more in your paychecks and get a smaller refund at tax time.
Affordable Care Act (ObamaCare) Tax Guide
February 3, 2015
How long to keep income tax returns and related records