The short answer
Run the free IRS Tax Withholding Estimator with your latest pay stub, then give your employer a new Form W-4 with the result. The earlier in the year you do it, the smaller the change per paycheck.
Last reviewed: October 2026
Step by step
- Grab your most recent pay stub (and your spouse's, if married) and last year's return.
- Go to the IRS Tax Withholding Estimator on IRS.gov and answer the questions.
- It fills out a W-4 for you. Download it.
- Give it to your employer or update it in your payroll app.
- Check your next pay stub to make sure the change took effect.
Quick check first: our Will I owe? calculator uses your pay stub to show if you're on track.
Common fixes
- Two jobs or two earners: check the box in Step 2 of the W-4, on one W-4 only.
- Side income: add it in Step 4(a), or add extra withholding per paycheck in Step 4(c).
- Retirement income: use Form W-4P for pensions and W-4V for Social Security.
Late in the year? A bigger extra amount per paycheck for the last few months can still close the gap. See Why do I owe this year?
Official source: IRS: Tax Withholding Estimator.
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Disclaimer: This page is general information, not tax advice. Every situation is different, and tax rules change. Reading this page doesn't make you a client.