There are many reasons to check your tax withholding. This means looking to see how much money your employer is withholding from your paycheck for federal income tax. Remember, you can visit IRS.gov/withholding any time for more info. It's a good idea to check your withholding as it will help you avoid a surprise at tax time. See, if your employer is withholding too little, you could end up with a tax bill or a penalty. Withholding too much can mean you won't be able to use the money until you get your tax refund. The best way to check your withholding is to use the Tax Withholding Estimator on IRS.gov. You might be asking WHEN to check your withholding. Well, it's always a good idea to check it early in the year, when any tax law changes typically go into effect, and when you have life changes, such as getting married, a job change, or any other change to your income. For more information about withholding – including how to change the amount of tax your employer withholds and to access the Tax Withholding Estimator, visit IRS.gov/withholding.