When you start a new job, you'll usually be asked to fill out a W-4 Form, or Employee's Withholding Certificate. Using the information you supply, your employer will calculate how much money to withhold from your paychecks to cover your federal income taxes when they come due. The first section of the W-4 asks you to check a box to indicate whether you are "Single or Married filing separately," "Married filing jointly or Qualifying widow(er)," or "Head of Household." This article explains what it means to check the boxes for single or married tax withholding.

Key Takeaways

  • IRS Form W-4, which you file with your employer when you start a job, is used to calculate how much money will be withheld from your paycheck to cover taxes.
  • The form asks whether you are single or married, as well as the number of your dependents, if any.
  • In general, married couples who file their taxes jointly will have less withheld from their paychecks than singles.

Single Withholding vs. Married Withholding

The three boxes on the W-4 Form (Single or Married filing separately, Married filing jointly or Qualifying widow(er), and Head of Household) correspond to the filing statuses that taxpayers have to choose from when they file their annual Form 1040 tax returns. (Form 1040 breaks them into five categories, giving "Single" and "Married filing separately," for example, their own check boxes.)

To qualify as a head of household (HOH), the taxpayer must be unmarried and also supporting another person.

Married taxpayers can choose to file jointly on the same tax return, or separately on different tax returns, whichever is more advantageous in their situation. In most cases, filing a joint tax return will result in a lower tax bill.

Which box you check on your W-4 will determine the standard deduction and tax rates that are used to compute your withholding. All else being equal, married taxpayers who plan to file jointly will have less withheld on a percentage basis than singles or people with other statuses. That's because married taxpayers are likely to pay less tax when they file their returns for the year.

The standard deduction for single taxpayers and married individuals filing separately, for example, is $12,400 for tax year 2020, while marrieds filing jointly get twice that, or $24,800. Similarly, singles are taxed at the lowest marginal tax rate of 10% on just their first $9,875 in income, while married couples filing jointly are taxed at that rate on their first $19,750 in income (again, for tax year 2020). At higher marginal tax brackets, married taxpayers continue to benefit. 

If your marital status changes, you'll want to submit a new W-4 Form so your employer can adjust your tax withholding.

How Dependents Fit In

The Internal Revenue Service (IRS) substantially redesigned the W-4 form for 2020, a change necessitated by the Tax Cuts and Jobs Act's elimination of the personal exemption. So if you haven't filled out a W-4 in a few years, you will find it looks very different today.

In particular, the form no longer asks you to calculate (or guess at) your number of withholding allowances. Instead, taxpayers whose income is under $400,000 (for marrieds filing jointly) or $200,000 (for other filing statuses) are instructed to multiply their number of qualifying children under age 17 by $2,000 and any other dependents by $500 and enter those dollar figures on the form.

Using that information, plus your filing status, your employer will calculate how much to withhold from your pay.

Other Considerations

Bear in mind that if you have more money than necessary withheld from your paycheck you've lost the use of that money throughout the year, although you should get it back later as a tax refund. If you have too little withheld, you may face a big tax bill and also an underpayment penalty.

Also note that you can always file a new W-4 with your employer to adjust your withholding. In particular, you will want to do that if your filing status changes from "single" to "married," or vice versa.