Federal W-4 vs. State Withholding Forms
State withholding form requirements
| State Type | Separate Form? | Examples | Notes |
|---|---|---|---|
| No state income tax | No form needed | FL, TX, WA, NV, WY, SD, AK | No state income tax withholding |
| State uses federal W-4 | No — federal W-4 serves both | CO, NM (some states) | State piggybacks on federal W-4 |
| State has separate form | Yes — complete state form separately | CA, NY, IL, OH, MA, most states | Complete state form AND federal W-4 |
California employees complete both the federal W-4 and the California DE-4 (Employee’s Withholding Allowance Certificate). New York employees complete both federal W-4 and NY IT-2104. Illinois uses IL-W-4. Most states with income taxes have their own form — check with your employer’s HR or state tax authority for the correct state form.
When State Withholding Is Insufficient
State withholding errors happen for the same reasons as federal ones: dual income, side income, or never updating the form after a life change. Most states have their own underpayment penalty (typically 5–12% annualized) similar to the federal 8%. Review your state withholding form annually alongside your federal W-4 review.
When running the federal IRS estimator, also estimate your state income tax and verify your state withholding covers it. Many state revenue department websites have their own withholding estimators.
Calculate Your Federal W-4 Settings
After setting federal withholding, use your state’s estimator to verify state withholding is also accurate.