Whether or not you owed taxes or received a refund last year, check your tax withholding to avoid not having too little tax withheld and facing an unexpected tax bill or penalty at tax time next year. This is even more important due to the recent changes to the tax law for 2018 and beyond. On the other end, if you had a large refund you lost out on having the money in your pocket throughout the year. Changing jobs, getting married or divorced, buying a home or having children can all result in changes in your tax calculations. The IRS withholding calculator on IRS.gov can help compute the proper tax withholding. The worksheets in Publication 505, Tax Withholding and Estimated Tax can also be used to do the calculation. If the result suggests an adjustment is necessary, you can submit a new W-4, Withholding Allowance Certificate, to your employer.