Form W-4: What It Is and How to Fill It Out

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Form W-4, officially the Employee’s Withholding Certificate, is the IRS form you give your employer so it knows how much federal income tax to take out of each paycheck. It sets how much you prepay through payroll, not how much tax you owe for the year. Your employer keeps it rather than sending it to the IRS, and uses your filing status, other jobs, expected credits, other income and deductions to calculate withholding. The form has five steps. Steps 1 and 5 apply to everyone, and Steps 2 through 4 apply only if they fit your situation.

What Form W-4 Does

Employers must withhold income tax from wages because the federal system is pay-as-you-go: you pay tax as you earn income, not in one lump sum the following April. Your employer sends the withheld money to the IRS and reports the totals on your Form W-2. When you file your Form 1040, the withholding is credited against your total tax. Too much withheld means a refund. Too little means you owe the balance, and possibly a penalty.

Withholding also applies to vacation pay, bonuses, commissions and some expense allowances, not just base salary.

Employers give new hires a W-4 with other onboarding paperwork such as Form I-9. The current form is a single page with five steps, followed by instructions and worksheets, and many employers let you submit it electronically through their payroll system.

What Happens If You Don’t Submit a W-4

Without a valid W-4 from you, your employer has no discretion. It must withhold as if you were single or married filing separately, using only that status’s standard deduction with no credits or other adjustments. If you’re married filing jointly or qualify as head of household, this usually takes out more than your actual liability requires, and you get the excess back only after you file.

Filling out the form so it withholds too little brings the opposite risk: a bill at filing time and possibly an underpayment penalty. The IRS waives that penalty only in limited cases, for example if you retired after age 62 or became disabled during the tax year or the year before, and the underpayment had reasonable cause rather than willful neglect.

How to Fill Out Form W-4, Step by Step

Step 1: Personal information

Enter your name, address and Social Security number, and confirm whether your name matches your Social Security card. Then check one filing status box: single or married filing separately, married filing jointly (or qualifying surviving spouse), or head of household.

Your filing status sets which standard deduction and tax brackets your employer’s calculation uses. Head of household is more favorable than single. You generally qualify if you’re considered unmarried, pay more than half the cost of keeping up your home, and have a qualifying person living with you. Single parents often meet these conditions, so check before defaulting to “single.”

If Step 1 is all that applies to you (one job, no working spouse, no dependent credits, no adjustments), skip to Step 5 and sign.

Step 2: Multiple jobs or a working spouse

Complete Step 2 if you hold more than one job at the same time, or if you’re married filing jointly and your spouse also works. Each employer calculates withholding as if its job were your only income, applying the full standard deduction and lower brackets to its share of the pay, so combined withholding usually falls short.

The form gives three options. Use one of them:

1. (a) The IRS Tax Withholding Estimator. This online tool gives the most precise result and is the best choice when your situation has several moving parts.
2. (b) The Multiple Jobs Worksheet. On page 3 of the form, it uses tables to produce an extra withholding amount that you enter in Step 4(c).
3. (c) The checkbox. Use it only if there are two jobs total in the household, and check it on the W-4 for both jobs. It’s accurate when the two jobs pay roughly the same. If the lower-paying job earns less than about half of the higher-paying one, use option (b) instead.

Married filing jointly where one spouse has two jobs: that household has three jobs, so the checkbox doesn’t apply. Use the estimator or the Multiple Jobs Worksheet, which handles up to three jobs. Complete Steps 3 through 4(b) on only one W-4, preferably for the highest-paying job, so credits and deductions aren’t counted twice.

Step 3: Claim dependents

Step 3 converts expected dependent credits into a dollar figure that reduces your withholding. The form limits this step to filers whose income will be $200,000 or less ($400,000 or less if married filing jointly).

On the 2025 version of the form, the math works like this:

• Multiply the number of qualifying children under age 17 by $2,200.
• Multiply the number of other dependents by $500.
• Add the two results and enter the total.

These amounts track the Child Tax Credit and the Credit for Other Dependents, so use the figures printed on the form for the year you’re filing. Hypothetical example: a parent with two children under 17 and an elderly parent who qualifies as a dependent would enter (2 × $2,200) + (1 × $500) = $4,900 using the 2025 amounts.

“Other dependents” don’t have to be your children. An adult relative can qualify, and so can an unrelated person who lives with you all year. In both cases, their gross income must be below the IRS threshold and you must provide more than half of their support.

Step 3 is voluntary. Entering every dependent you expect to claim gives the most accurate withholding. Leaving dependents off means more tax is withheld, which some people do on purpose to cover untaxed side income. Married couples should not both claim the same children on their separate W-4s: that doubles the credit in payroll and leads to underwithholding.

Step 4: Other adjustments

Step 4 is optional and has three parts. You can use any combination.

• 4(a) Other income. Income not from jobs and not subject to withholding, such as interest, dividends, retirement income or capital gains. Entering it increases your withholding to cover the tax on it. Self-employment income usually belongs in estimated tax payments instead.
• 4(b) Deductions. If you expect to itemize or claim certain deductions beyond the standard deduction, complete the Deductions Worksheet: estimate your total deductions, subtract the standard deduction for your filing status, and add adjustments such as deductible IRA contributions or student loan interest. The result goes on line 4(b) and lowers your withholding. Leave it blank if your itemized deductions won’t exceed the standard deduction.
• 4(c) Extra withholding. A flat dollar amount taken from every paycheck on top of the normal calculation. The Multiple Jobs Worksheet result goes here, and you can add more.

Hypothetical example for 4(c): suppose you expect $1,200 of additional tax from freelance work and you’re paid 24 times a year. Entering $50 in Step 4(c) spreads that liability across your remaining paychecks. If you start midyear, divide by the number of pay periods left, not the full year.

Step 5: Sign and date

An unsigned form isn’t valid, and your employer will treat you as if you never turned one in. The final section, with the employer’s name, address, first date of employment and EIN, is for your employer to complete.

How Much Should You Have Withheld?

The target is withholding that roughly matches your total tax for the year. More withholding means a larger refund, and less means more take-home pay during the year, but neither changes your actual tax. Overwithholding works like an interest-free loan to the government. Underwithholding risks a bill and penalties.

Situations where the default calculation tends to miss include:

• side income, dividends, rental income or retirement distributions with no tax withheld
• two earners in the household, or multiple jobs
• large itemized deductions or credits beyond the dependent credits
• starting or leaving a job partway through the year

The IRS Tax Withholding Estimator shows how a set of W-4 entries affects your expected refund or balance due and your take-home pay, and it produces a filled-in form you can give your employer. A recent pay stub and last year’s return make the results more accurate.

Claiming Exemption From Withholding

Exemption is a separate choice from the steps above, and it’s narrow. You can claim it only if both conditions hold: you had no federal income tax liability last year, and you expect none this year. Students with part-time or summer jobs often fit this description. To claim it, you write “Exempt” in the space below Step 4(c) and complete only Steps 1(a), 1(b) and 5.

The exemption lasts one calendar year. To keep it, you must submit a new W-4 claiming exemption by the deadline the IRS sets each year, normally mid-February. Otherwise your employer reverts to the default withholding described above. The exemption covers federal income tax only: Social Security and Medicare taxes are still withheld from every paycheck.

Updating Your W-4 When Things Change

You can submit a new W-4 whenever you want to change your withholding: ask your employer for a fresh form, use your payroll portal, or download the current year’s version from the IRS. Otherwise your form stays in effect until you replace it. Marriage, divorce, a new child, a second job, a side business or a big change in deductions are common reasons to redo it, and waiting until year-end leaves fewer paychecks to make up a shortfall.

Your employer must put a new W-4 into effect no later than the start of the first payroll period ending on or after the 30th day after it receives the form. You must file a new one within 10 days when a change means your current W-4 would produce too little withholding for the year. The IRS lists these triggers:

• You or your spouse expect a raise of more than $10,000 in regular wages (not a bonus) at a second or third job, and the Step 2(c) checkbox isn’t selected on your W-4s.
• You no longer expect to claim a Child Tax Credit you accounted for on a previous W-4.
• Other credits you entered on a previous W-4 drop by more than $500.
• Your deductions drop by more than $2,300 from the amount on a previous W-4.
• You no longer reasonably expect to qualify for exemption from withholding.

How the Form Has Changed

Before 2020, the W-4 was built around withholding allowances, each tied to the personal exemption: more allowances meant less withholding. The Tax Cuts and Jobs Act eliminated personal exemptions, which removed the basis for allowances. The IRS redesigned the form for 2020 around direct dollar amounts for credits, other income, deductions and extra withholding, plus the multiple-jobs step.

Employees who submitted a W-4 before 2020 don’t have to file the new version. Their employer keeps withholding based on the old form until they submit a new one. Any change you make now, however, must use the current form. If you see advice about “claiming 0” or “claiming 1,” it refers to the old allowance system, which no longer exists.

FAQs

The Bottom Line

Anyone who starts a job, adds a second income, marries, has a child or picks up side work should review their W-4. The form controls how much tax you prepay, so accurate entries keep you from lending money to the government or facing a bill and penalty. Running your numbers through the IRS Tax Withholding Estimator and filing a new form promptly after a change gives you more paychecks to correct any gap.