What Is an Employee Withholding Certificate (W-4)?

An employee withholding certificate, better known as IRS Form W-4, is the document you give your employer so the correct amount of federal income tax comes out of each paycheck. Your employer uses your entries to estimate what you’ll owe at year-end and spreads that amount across your pay periods. Fill it out carefully and your April tax bill lands close to zero. Fill it out sloppily and you either owe money you didn’t plan for or hand the Treasury an interest-free loan for twelve months.

Federal law requires employers to withhold income tax from wages and send it to the IRS.¹ The W-4 is the instruction sheet that tells them how much.²

How to Fill Out the Five Steps

The current W-4 uses dollar amounts and plain questions rather than the old allowances system. Steps 1 and 5 are required. Steps 2, 3, and 4 apply only if your situation calls for them, and leaving them blank is fine when they don’t.

Step 1: Personal Information and Filing Status

Enter your legal name as it appears on your Social Security card, your Social Security number, your address, and your filing status. Filing status drives the standard deduction and tax brackets your employer plugs into the withholding formula. For 2026, the standard deduction is $16,100 for single filers, $32,200 for married couples filing jointly, and $24,150 for head of household.³ Picking the wrong status here ripples through every paycheck the rest of the year.

Step 2: Multiple Jobs or a Working Spouse

Fill this out if you work more than one job at the same time, or if you’re married filing jointly and your spouse also works. Without it, each employer treats your wages as your only income and underwithholds. You have three options: use the IRS Tax Withholding Estimator at irs.gov, complete the Multiple Jobs Worksheet on page 3 of the form, or check the box in Step 2(c) when there are only two jobs and the pay is roughly similar. The estimator is the most accurate because it uses your actual year-to-date withholding.

If you’d rather not tell your employer you have another job or a working spouse, complete the worksheet privately and enter the calculated amount as extra withholding in Step 4(c).⁴ Your employer sees a dollar figure and nothing about why.

Step 3: Dependent Credits

Step 3 reduces your withholding to reflect the child tax credit and the credit for other dependents. The form instructions show the current amount for each qualifying child under 17 and a $500 credit for each other dependent.² Multiply the number of dependents by the applicable credit and enter the total. The benefit shows up in every paycheck rather than at tax time. The credit phases out beginning at $200,000 of income, or $400,000 for joint filers.⁵

Step 4: Other Adjustments

Step 4 has three optional lines for fine-tuning.

Line 4(a) is for other income not subject to withholding, such as interest, dividends, or retirement distributions. Entering the expected annual amount here pulls enough extra tax from your wages to cover it. If you don’t want your employer to see the figure, convert it to a per-paycheck amount and put it in line 4(c) instead.⁴

Line 4(b) is for itemized deductions. If you plan to itemize and the total (mortgage interest, charitable contributions, state and local taxes) will exceed the standard deduction, enter the difference. The Deductions Worksheet on page 3 walks through the math.

Line 4(c) is a flat dollar amount added to withholding each pay period. Use it as the privacy alternative described above or simply to build a larger refund.

Step 5: Signature

Sign and date the form. Your signature is made under penalty of perjury, so you’re certifying the entries are accurate to the best of your knowledge.

Turning It In and When the Change Hits Your Paycheck

Give the completed W-4 to payroll or human resources, or enter it through your employer’s payroll portal if that’s how your company handles it. You don’t send anything to the IRS yourself; your employer keeps the form.

When you replace an existing W-4, federal rules give your employer up to 30 days to implement the change. The new withholding must begin no later than the first payroll period ending on or after the 30th day after your employer received the form.⁶ Most employers move faster than that. Check the pay stub after the next cycle or two to confirm your numbers changed.

When You Should File a New W-4

A W-4 has no expiration date for most filers. It stays in place until you replace it. The IRS recommends reviewing your withholding every year,² and certain life events should prompt an update sooner:

Marriage or divorce, which changes your filing status.
A new child or dependent, which adds a credit you can claim through payroll.
A spouse starting or stopping work.
A second job or freelance income on top of your regular wages.
A meaningful change in non-wage income such as investments, rental property, or retirement distributions.

Timing matters. Events that let you claim more allowances or credits (having a child, for instance) can wait until it’s convenient. Events that reduce what you’re entitled to claim require a new W-4 within 10 days. Missing that deadline can leave you underwithheld, and the IRS charges interest on tax you should have paid across the year.

Claiming Exempt from Withholding

You can write “Exempt” on your W-4 and have no federal income tax withheld, but only if you had zero federal income tax liability last year and expect zero again this year.⁶ Both conditions must be true. This usually applies to part-time students and seasonal workers earning well under the standard deduction.

Exempt status expires annually. You have to file a new W-4 claiming the exemption by February 15 each year. Miss the date and your employer must start withholding as if you were single with no adjustments,⁶ typically the highest rate for your income.

If You Never Submit a W-4

Skipping the form doesn’t mean skipping withholding. Your employer must treat you as a single filer with no entries in Steps 2 through 4.⁷ For someone married with dependents, that means substantially more tax withheld than needed. You get the excess back as a refund, but only after tax season.

IRS Lock-In Letters

If the IRS decides your withholding is too low, it can send your employer a “lock-in letter” (Letter 2800C) setting the withholding rate your employer must use. Once the lock-in takes effect 60 days after the letter date, your employer cannot go below that level even if you submit a new W-4 asking for less. You can still ask for more withholding, but any request to reduce it has to go to the IRS directly. Your employer must also block you from lowering withholding through any online portal while the lock-in is active.⁸ Lock-in letters typically follow chronic underwithholding. If you get one, you have a window before it kicks in to send the IRS a corrected W-4 with documentation.

Penalties for False Entries

Willfully putting false information on a W-4, or intentionally failing to report a change that should increase your withholding, is a federal crime punishable by up to one year in prison and a fine of up to $1,000 under the base statute.⁹ The IRS can also assess a $500 civil penalty for a false W-4.⁶ The word “willfully” is doing real work here. Miscounting dependents is an error. Claiming exempt when you know you’ll earn $80,000 is fraud.

Nonresident Alien Employees

If you’re a nonresident alien working in the U.S., the regular W-4 instructions don’t fully apply. Your employer must add a fixed amount to your wages before running the withholding calculation. For W-4s submitted for 2020 or later, that add-on ranges from $309.60 per week to $16,100 annually depending on your pay frequency. The add-on is used only for the withholding math; it doesn’t change your reported wages or your Social Security and Medicare taxes. Before filling out the form, read IRS Notice 1392 for the supplemental instructions. Students and business apprentices from India follow separate rules and may not be subject to the additional amount.⁷

1
Office of the Law Revision Counsel. 26 USC 3402 – Income Tax Collected at Source
2
Internal Revenue Service. About Form W-4, Employee’s Withholding Certificate
3
Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026, Including Amendments From the One, Big, Beautiful Bill
4
IRS. Employee’s Withholding Certificate
5
Internal Revenue Service. Child Tax Credit
6
Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide
7
Internal Revenue Service. Publication 15-T (2026), Federal Income Tax Withholding Methods
8
Internal Revenue Service. Understanding Your Letter 2800C
9
Office of the Law Revision Counsel. 26 USC 7205 – Fraudulent Withholding Exemption Certificate or Failure to Supply Information