What Is a W-4?
The W-4 (Employee’s Withholding Certificate) tells your employer how much federal income tax to withhold from each paycheck. Getting it right means no surprise tax bill in April — and no over-withholding that gives the IRS an interest-free loan.
When to Complete a W-4
- When you start a new job
- After getting married or divorced
- After having or adopting a child
- After a significant income change
- After a major life event that affects taxes
Step-by-Step: The 2025 W-4
Step 1 – Personal Information Enter your name, address, SSN, and filing status. Most single filers stop here.
Step 2 – Multiple Jobs or Spouse Works Complete this if you (or your spouse) have multiple jobs. The IRS withholding estimator at irs.gov gives the most accurate result.
Step 3 – Claim Dependents Multiply the number of qualifying children under 17 by $2,000 and enter the total. This reduces withholding to reflect the Child Tax Credit.
Step 4 – Other Adjustments (Optional)
- 4(a): Other income not from jobs (dividends, self-employment)
- 4(b): Deductions you plan to itemize above the standard deduction
- 4(c): Any extra flat dollar amount to withhold each pay period
Step 5 – Sign and Date
Tips for Accuracy
- Use the IRS Tax Withholding Estimator (irs.gov/w4app) for complex situations
- If you had a large refund last year, increase withholding adjustments in Step 4(b)
- If you owed money last year, add extra withholding in Step 4(c)
- Review your W-4 every year, especially after life changes
Common Mistakes
- Claiming “Exempt” when you’re not (only valid if you had zero tax liability last year AND expect zero this year)
- Forgetting to update after getting married — your new combined income may push you into a higher bracket
- Not accounting for side income on a main employer’s W-4