Form W-4
Employee's Withholding Certificate
The federal form completed by employees to direct their employer how much federal income tax to withhold from each paycheck.
Who Files Form W-4
Every US employee starting a new job, plus existing employees who want to adjust withholding after a major life event (marriage, divorce, second job, child, large equity vesting, etc.). The W-4 is given to the employer, not the IRS.
What Form W-4 Reports
The redesigned W-4 (post-2020) eliminated allowances. Employees now report filing status, multiple-job adjustments, dependents and credits, other income (interest, dividends), additional deductions, and an extra dollar amount to withhold per pay period (line 4(c)). The IRS Tax Withholding Estimator at IRS.gov is the recommended tool for accurate completion.
Key Deadlines
- Submit at hire and any time withholding needs adjustment
- No annual filing deadline
- Update after major life events to avoid year-end balance-due surprises
Common Mistakes
- Failing to update W-4 after a major equity vesting event (RSUs commonly under-withheld at the flat 22 percent supplemental rate)
- Ignoring the multiple-jobs adjustment on Step 2 when both spouses work or there are second jobs
- Marking exempt without qualifying (requires owing zero tax in prior and current year)
- Forgetting to refresh the W-4 after a divorce or after a child ages out of the Child Tax Credit
Best Practices
- Use the IRS Tax Withholding Estimator at IRS.gov/W4app once a year, especially after marriage, divorce, a new job, RSU vesting, or buying a home.
- For households with two earners, complete Step 2 carefully. The Multiple Jobs Worksheet or the IRS estimator output goes on Step 4(c) extra withholding.
- After a major equity vesting event (RSUs, NQSOs), set Step 4(c) extra withholding to cover the gap between the 22 percent supplemental rate and your marginal rate.
- Refresh the W-4 every January and again mid-year if your income or deductions changed. The IRS encourages annual review.
- Resist the temptation to claim Exempt to maximize take-home. Exempt requires owing zero tax in the prior and current year, and the IRS audits frivolous Exempt claims.
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W-2
Form W-2
The annual statement employers provide to employees and the Social Security Administration reporting wages paid and federal, state, and local taxes withheld.
1040
Form 1040
The annual federal income tax return filed by US citizens and resident aliens to report income, deductions, credits, and tax liability.
1040-ES
Form 1040-ES
Quarterly federal estimated tax payments for self-employed individuals, investors, retirees, and others whose income is not subject to sufficient withholding.
Related Tax Terms
Form W-2 (Wage and Tax Statement)
The annual statement employers provide to employees and the Social Security Administration reporting wages paid and federal, state, and local taxes withheld.
Restricted Stock Unit (RSU)
A form of employer equity compensation that delivers shares (or cash equivalent) to an employee upon vesting, taxed as ordinary income at vesting.
Estimated Tax
Quarterly tax payments made by self-employed individuals, investors, and others whose income is not subject to sufficient withholding.
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