The chance you are under-withholding taxes may be higher than you think. A report by the Government Accountability Office (GAO) suggests that a fifth of taxpayers, more than 30 million people, may owe taxes due to under-withholding. 

If you're one of those people, you can avoid a penalty by taking one of the

actions outlined below.

Key Takeaways

  • Nearly one out of five taxpayers may have owed taxes due to changes made in the Tax Cut and Jobs Act of 2017. 
  • Many people are coping with under-withheld taxes because the U.S. Treasury Department did not update the personal withholding amount to reflect changes in the tax law.
  • Likely candidates for under-withholding include married taxpayers with multiple children, those who have non-wage income, and those who are self-employed. 
  • Depending on the amount of the under-withholding, and whether or not you compensate for it before the deadline, under-withholding penalties can apply. 
  • There are a variety of waivers you can qualify for to avoid this penalty. 

The GAO Report

Your employer is required to withhold taxes on your pay based on withholding tables provided by the Internal Revenue Service (IRS), but you can reduce the amount withheld by claiming withholding allowances. Historically, allowances have been based on personal exemptions, which no longer exist due to changes brought on by the Tax Cuts and Jobs Act (TCJA).

According to the GAO, the U.S. Treasury Department chose the same withholding allowance value ($4,150 for 2018) that would have existed under old tax law. This resulted in 30 million people under-withholding in 2018, vs. 27 million who would have under-withheld under previous tax law. 

If you want to learn more about how changes to taxes may affect you, there are two documents that can help, both from the IRS. Publication 5307, titled Tax Reform: Basics for Individuals and Families, and Publication 5318, titled Tax Reform: What’s New for Your Business are great places to start. 

Why Under-Withholding Is a Problem

The U.S. tax system operates on a "pay as you go" (sometimes called "pay as you earn") basis, meaning you are required to withhold or pay estimated taxes during the tax year. The elimination of the personal exemption, changes to withholding tables brought on by the TCJA, and the fact that taxpayers were encouraged, but not required, to file an updated W-4 Form may have resulted in under-withholding of taxes for millions of taxpayers. 

People Who Should Be Concerned

According to the GAO, a married taxpayer with two children who earns $180,000 annually, including $20,000 from non-wage income—and who itemizes deductions—is a likely candidate for under-withholding. You may also find yourself under-withholding in the following circumstances:

  • You itemized in the past but now plan to take the higher standard deduction.
  • You are part of a two-wage earner household with no children or children age 17 or above.
  • You have self-employment or other non-wage income.
  • You received year-end bonuses, stock dividends, or capital gains.
  • You owe the alternative minimum tax or tax on unearned income of minors.
  • You realized a profit from property sales.
  • You live in a high-tax state and are losing part of your state and local tax (SALT) deductions.
  • You have significant unreimbursed employment-related expenses no longer deductible under TCJA.
  • You have gambling winnings for which taxes were not withheld.

If any of these apply to you—and you also failed to update your withholding—the risk of under-withholding is even greater.

When the Penalty Kicks In

Normally, an underpayment penalty may apply if the amount withheld (or paid through estimated taxes) is not equal to the smaller of 90% of the taxes you owe for the current year or 100% of the taxes you owed for the previous year.

If a penalty applies, it is typically 0.5% of the amount owed for each month that amount was unpaid.

Interest charges may also apply.

Additional Available Waivers

The penalty may also be waived under these circumstances.

  • You owed no taxes last year.
  • You have tax liability (minus payments already made) for this year of less than $1,000.
  • You missed an estimated payment due to a casualty, disaster, or other unusual circumstances.
  • You retired after reaching age 62 and that was the cause of the under-withholding.
  • You became disabled during the previous or current tax year and failed to make estimated payments for that reason.
  • You had any other situation in which underpayment was not due to willful neglect on your part.

Even if you don’t qualify for a waiver, you may qualify for a reduced penalty in certain circumstances, including a change in marital status or substantial income realized late in the year.

What You Should Do

Determine whether you under-withheld taxes. The 2019 version of Form 1040 and instructions are on the IRS website along with many supplemental forms and schedules.

File Form 2210

If you under-withheld taxes last year you must file Form 2210, Underpayment of Estimated Tax by Individuals, Estates, and Trusts with this year's income tax return no later than April 15.

Complete Part I of Form 2210 and the included worksheet and instructions to determine whether a waiver applies in your case.

If a waiver does not apply, you will likely owe a penalty. In some cases, the IRS will figure the penalty for you. In other cases, you must use Form 2210 to figure the penalty yourself. See Form 2210, instructions and worksheet for more information.

The Bottom Line

Check your eligibility for the waiver as well as other waivers for which you might qualify.

If you under-withheld last year, whether you qualify for a waiver or not, check your withholding to avoid this problem in the future. Use the updated online IRS Withholding Calculator to help you adjust withholding amounts.