How to Avoid Under-Withholding
The plain answer
Section titled “The plain answer”Under-withholding means too little federal income tax is being paid from your paychecks compared with what you are likely to owe for the year. That can leave you with a balance due and, in some cases, an underpayment penalty.
Review your Form W-4 and update it after changes to your jobs, income, filing status, dependents, deductions, credits, or household. If you also receive income without withholding, consider making estimated tax payments.
How it actually works
Section titled “How it actually works”Your employer calculates federal income tax withholding using your taxable wages, pay frequency, and the current W-4 steps. The current form does not use allowances, so advice about claiming fewer allowances is outdated.
Check each applicable part of the form:
- Select the filing status you expect to use.
- Use Step 2 when you have more than one job at a time or file jointly with a working spouse.
- Enter qualifying dependent and other credit amounts in Step 3.
- Use Step 4 for other income, deductions, and any extra amount you want withheld from each paycheck.
Step 4(c) lets you request extra withholding per pay period. This can help cover tax from bonuses, a second job, investment income, or other amounts not fully addressed elsewhere. Estimate the annual gap before converting it to a per paycheck amount.
Withholding is a prepayment, not a separate tax. Your return compares your total tax with withholding, estimated payments, and other payments. Read what tax withholding means and how taxes actually work for the full picture.
What this means for you
Section titled “What this means for you”Project your income and tax for the full year, then compare the result with expected withholding and other payments. Make a new W-4 adjustment early enough for the remaining paychecks to cover the gap. Recheck after a raise, bonus, new job, marriage, divorce, new child, change in a spouse’s work, or a large change in nonwage income.
If the shortfall comes from self-employment, investments, rental income, or another source without payroll withholding, estimated payments may be more practical than placing the entire burden on one paycheck. You can also combine estimated payments with extra W-4 withholding.
Plan around the tax you expect to owe, not around purchases made only for a deduction. Do not spend a dollar to save thirty cents in taxes.
Common mistakes
Section titled “Common mistakes”- Using old W-4 allowances language instead of the current form’s steps
- Ignoring a second job or a working spouse’s income
- Assuming every bonus has enough tax withheld
- Forgetting income that does not have withholding
- Requesting extra withholding once and failing to update it after life changes
- Waiting until the final paycheck to correct a full year shortfall
- Confusing a balance due with being taxed twice
Related pages
Section titled “Related pages”Educational content, not personalized financial, tax, or legal advice. No affiliate relationships. Figures are for tax year 2026 and change annually.Read the full disclaimer.