Annual Evaluation of withholding is a personal finance best practice that has become even more essential after tax reform's changes to individual tax rates and brackets. During the 2018 tax year, many individuals realized the need to adjust their withholding to realign with their new income tax liability. The IRS recommends performing a "payroll checkup" and adjusting W-4s as needed to ensure adequate tax is withheld. When updating withholding, make sure to use the most recent version of the W-4.
Visit irs.gov/withholding for a free calculator and more information on withholding.