Underwithholding may still be a risk
To reflect changes under the Tax Cuts and Jobs Act (TCJA) — such as the increase in the standard deduction, suspension of personal exemptions and changes in tax rates and brackets — for 2018 the IRS updated the tables that indicate how much employers should withhold from their employees’ paychecks for federal income taxes. Generally the amount withheld was reduced.
As a result, some taxpayers didn’t have enough withheld to pay their ultimate tax liabilities under the TCJA. They found themselves with an unexpected tax bill when they filed their 2018 tax returns. In some cases, taxpayers even owed interest and penalties, though the IRS has provided some relief in certain circumstances.
The withholding tables for 2019 are very similar to those for 2018, so you may still be at risk for underwithholding. An IRS calculator can help you more accurately estimate how much should be withheld. (Go to IRS.gov and search “withholding.”) You may find that you need to increase your withholding by filling out a new Form W-4 and submitting it to your employer. You can modify your withholding at any time during the year, or even multiple times within a year.