Tax · W-4
Fill W-4 online — free, takes 30 seconds
The W-4 tells your employer how much federal income tax to withhold from your paycheck. New job, married, had a kid, picked up a side hustle? Time to update it.
Who needs it: Every US employee at every new job. Anyone who wants to adjust their withholding after a life change (marriage, kids, second job, big bonus).
Need a blank W-4? Download from the source, then drop it in below.
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Why fill it here
- Auto-fill personal info (name, address, SSN, filing status) from your profile.
- Built-in IRS worksheet helpers for dependents and multiple-job adjustments (coming soon).
- Sign and email to HR without leaving your browser.
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W-4 questions, answered
General information, not legal or tax advice
This page is general information about a commonly-used tax form. Tax law is complex and fact-specific — for advice on your return, consult a CPA, enrolled agent, or tax attorney. AttachKit fills the PDF; the IRS holds you responsible for what's on it.
- Does this calculate the right withholding for me?
- AttachKit fills the form. For complex situations (multiple jobs, large itemized deductions, capital gains), use the IRS Tax Withholding Estimator at irs.gov/W4App and copy the values into AttachKit.
- What if I want extra withholding?
- Line 4(c) lets you specify an extra dollar amount per pay period. AttachKit's profile has a field for this if you want it auto-filled too.