How to fill out a W-4, step by step.

What the W-4 actually does

When you start a job, your employer needs to know how much federal income tax to withhold from each paycheck. The W-4 gives them the inputs to a calculation: your filing status, whether you have other income, dependents you can claim, deductions you expect to take. The employer plugs those into the IRS’s withholding tables and arrives at a per-paycheck amount.

If the W-4 is right, your year-end tax bill comes out roughly even. If it’s wrong in either direction, you either owe a balance in April or get an outsized refund — both of which are your money on a different schedule, not free or punitive money.

The form, step by step

The 2020-redesigned W-4 has five steps. They’re short.

Step 1. Personal information and filing status. Name, address, Social Security number, filing status (single, married filing jointly, head of household). Almost everyone fills this in. This step alone is enough if you’re single, have one job, take the standard deduction, and don’t have dependents.

Step 2. Multiple jobs or a working spouse. Skip this if you have one job and your spouse doesn’t work. Otherwise, this is the step most often forgotten — and the cause of most April surprises. Three options:

• Use the IRS withholding estimator (see below) and enter the resulting amount in Step 4(c).
• Use the multiple-jobs worksheet on page 3 of the form.
• Check the box in Step 2(c) — only valid if both jobs pay roughly the same amount.

When you have two incomes, each employer withholds as if its salary is your only income. That under-withholds because progressive brackets apply to your combined income, not each piece. Step 2 corrects for that.

Step 3. Dependents. Use the multipliers printed on the W-4 form you’re filling out (the published amounts change with the tax year). For tax year 2026, multiply qualifying children under 17 by $2,200 (raised from $2,000 under the One Big Beautiful Bill Act, indexed thereafter) and other qualifying dependents by $500, then put the total here. This is how the Child Tax Credit and the Credit for Other Dependents get factored into withholding. Note: a paper W-4 you saved from before 2026 may still print $2,000 — use the amount on the most recent IRS-published form.

Step 4. Other adjustments (optional).

• 4(a): Other income (interest, dividends, side income) you want withholding to cover.
• 4(b): Deductions other than the standard deduction (itemized deductions above the standard amount, certain above-the-line deductions).
• 4(c): Extra withholding per pay period — the simplest way to add a fixed dollar amount to your withholding regardless of the rest of the form.

Step 5. Sign and date. The form isn’t valid until you sign it.

When to update it

You should re-do your W-4 when any of these change:

• You start a new job
• You get married, divorced, or widowed
• A dependent is born, adopted, or ages out (turns 17 for the CTC, 19/24 otherwise)
• You or your spouse start or stop a second job
• You buy a house and start having significant mortgage interest or property tax
• Your income changes substantially
• You got a big refund or owed a big balance last April

You can update your W-4 with HR at any time. There’s no penalty for redoing it, and there’s no rule limiting how often.

Use the IRS estimator

The IRS Tax Withholding Estimator at irs.gov is the single most useful tool for getting the W-4 right. It asks for:

• Your most recent pay stub
• Your spouse’s most recent pay stub (if applicable)
• Last year’s tax return for context

It outputs a recommended W-4 — usually with a specific dollar amount to put in Step 4(c) — that will get you to a near-zero balance in April. The whole exercise takes about fifteen minutes once a year. For most people, that’s the whole job. For a deeper read on the lines that flow through to your paycheck, our walkthrough on how to read a paycheck stub covers each one.