What Is a W-4 Form?

Form W-4 tells your employer how much to deduct from your pay.

You’re required to fill out an initial form W-4 tax form when you start a new job. The Internal Revenue Service recommends submitting an updated form annually or when you have any personal or financial changes to report, such as W-4 deductions or W-4 exemptions. Here’s what you need to know about the W-4, one of the most commonly used tax forms.

How Do I Fill Out a W-4?

An IRS W-4 form is a tax form that helps your employer withhold the correct amount of federal income tax from your paycheck, based on information you provide. Completing the form accurately can help you avoid having too little or too much tax withheld.

W-4 allowances are what you are allowed to claim to keep your employer from withholding too much tax from your earnings. You can claim an allowance for yourself, your spouse and for each dependent that you report on your tax return. You can also claim additional allowances under other circumstances, such as when filing head of household.

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Form W-4 Deductions and Adjustments Worksheet

You can find a printable W-4 form on the IRS website. Fill out the Personal Allowance Worksheet and Employee’s Withholding Allowance Certification on the 2018 or 2017 W-4 form, indicating whether you have a spouse and/or dependents. The worksheet also includes other information on situations that could affect your withholding, such as dependent care expenses.

You only need to use the Deductions and Adjustments Worksheet if you plan to itemize deductions on your IRS tax forms or you need to know what to claim on your W-4 in the way of specific adjustments or credits to your income, such as:

  • State and local taxes
  • Qualifying home mortgage interest
  • Deductions to charities
  • Medical expenses that were over 10 percent of your income

Find Out: How to Fill Out a W-4

Two-Earners / Multiple Jobs Worksheet

On the second page of form W-4, the Two-Earners / Multiple Jobs Worksheet applies to people who have more than one job or a working spouse. The IRS advises claiming all your allowances on the W-4 form for the highest paying job and claiming zero allowances for the others. This worksheet has a table and instructions to help you figure out the best way to handle the situation.

Making Changes and Corrections to Your W-4

You’re allowed to amend your IRS tax forms. Doing this gives you an opportunity to correct your federal income tax forms and pay any additional amount you should have paid initially or to get a higher refund. Search IRS forms online and choose Form 1040X to make the corrections. When you owe more money that should have been paid when you filed the original income tax return, pay it promptly to stop the accrual of interest charges.

Consider changing your W-4 form for the following reasons:

  • You have a change in marital status.
  • You give birth to or adopt a child and need to claim an additional dependent allowance.
  • You change or lose your job. When you start a new job, it’s often wise to increase the withholding amount to your new W-4 form to balance things out.
  • You get a raise or promotion.

Learn: Do You Know What’s Being Deducted From Your Paycheck?

Important Notes on Form W-4 Withholding

The information on your W-4 form directly affects the amount of your tax withholding. Keep the following details in mind when filling out or updating your W-4:

  • Your employer withholds less money from your paycheck if you claim more allowances.
  • You have to pay the IRS in a lump sum if too little is withheld.
  • Voluntarily raising the amount withheld avoids payments.

When you had no tax liability in the prior year and expect that circumstance to continue, you can declare yourself eligible for withholding tax exemption, which means that you are exempt from withholding on your W-4 form. This typically happens if your income is low enough for your personal exemption and standard deduction to wipe out the taxes.

Rather than trying to calculate the proper amount of allowances manually, use the IRS’s online withholding calculator to make your tax forms accurate. Prepare to use the calculator by gathering your most recent income tax return and paycheck stub.

Up Next: What’s a W-2 Form? 

About the Author

Barb Nefer has been writing professionally for nearly 30 years, cutting her teeth as a news writer for the Daily Southtown in Chicago. She’s a doctor of psychology, and her eclectic expertise includes personal finance, psychology, travel and the pet industry. Her work reflects that diversity, with pieces appearing in places like About.com, CBS Local, Yahoo.com, WebPsychology, and Animal Wellness magazine.