When to use the estimator.
Consider using the estimator at www.irs.gov/W4App if you:
1. Are submitting this form after the beginning of the year;
2. Expect to work only part of the year;
3. Have changes during the year in your marital status, number of jobs for you (and/or your spouse if married filing jointly), or number of dependents, or changes in your deductions or credits;
4. Receive dividends, capital gains, social security, bonuses, or business income, or are subject to the Additional Medicare Tax or Net Investment Income Tax; or
5. Prefer the most accurate withholding for multiple job situations.
TIP: Have your most recent pay stub(s) from this year available when using the estimator to account for federal income tax that has already been withheld this year. At the beginning of next year, use the estimator again to recheck your withholding.