What Is Withholding?
Federal income tax withholding is the process by which your employer deducts estimated federal income tax from each paycheck and sends it to the IRS on your behalf. It’s a pay-as-you-go system — rather than paying one large bill in April, you pay throughout the year.
How Is the Withholding Amount Calculated?
Your employer uses:
- Your W-4 form (filing status, adjustments, and extra withholding)
- IRS Publication 15-T withholding tables
- Your pay frequency (weekly, biweekly, semi-monthly, monthly)
The most common method: the employer annualizes your paycheck, looks up the tax in the bracket table, then divides by pay periods.
The Wage Bracket vs. Percentage Method
Wage Bracket Method: Employer looks up your withholding in a table using filing status and wages. Simple but less precise.
Percentage Method: More accurate; uses the 2024 tax brackets directly. Larger employers typically use this.
Why Does My Withholding Not Match My Actual Tax?
- Multiple jobs: Each employer withholds independently; combined income may be in a higher bracket
- Investment income: Not subject to withholding (you may need to pay estimated taxes)
- Side income (1099): No withholding at all
- W-4 not updated: Life changes affect optimal withholding
Over-Withholding vs. Under-Withholding
- Over-withholding: You get a refund. Sounds nice but you gave the IRS an interest-free loan.
- Under-withholding: You owe money (plus possibly a penalty if you underpay by more than $1,000 or less than 90% of your tax liability).
How to Adjust
File a new W-4 with your employer at any time. For complex situations, use the IRS Tax Withholding Estimator.