How Form W-4 maps to this paycheck calculator

Form W-4 tells payroll how to withhold federal income tax. It does not set Social Security or Medicare. Those FICA lines follow wage rules, not W-4 checkboxes. This page maps each W-4 step to what you can type on the paycheck calculator and what you cannot.

Step 1 — filing status

Step 1(c) is single or married filing separately, married filing jointly, or head of household. Payroll uses that status to pick which 15-T table or percentage-method standard deduction to apply. On this site, the three buttons at the top of the calculator are that choice. Married filing separately is treated like single for this estimate. Head of household is only accurate if you actually qualify; picking it because take-home looks better is how people under-withhold.

Step 2 — multiple jobs

If you have two jobs, or you are married and both spouses work, withholding from one job as if it were the only job usually takes too little tax. The W-4 has a checkbox and a worksheet for that. This calculator does not. It always treats the salary you entered as the only wage. If you have two jobs, run each salary separately and remember that stacking two “single job” estimates will understate combined federal tax. Use the IRS estimator when two jobs matter.

Step 3 — dependents

Step 3 is an annual dollar amount, not a headcount, on the real form. The common shortcut is $2,200 per qualifying child under 17 plus $500 per other dependent, which is what this site asks for as two counts. Payroll then withholds less federal income tax across the year. Credits can phase out at higher incomes; this site does not apply those limits. Entering dependents you cannot claim will inflate take-home here and can leave you short at filing.

Dependents never change the FICA percentages. If you add children and Social Security moves on a stub, look for a different gross, a pre-tax benefit change, or a combined “taxes” line. See FICA vs income tax.

Step 4 — other income, deductions, extra withholding

Step 4(a) is other income not from jobs. Step 4(b) is deductions other than the standard deduction. Step 4(c) is extra dollars to withhold each pay period. This calculator has none of those fields. If you currently have extra withholding on a stub, this page will show a higher take-home than you actually receive. If you have large itemized deductions, this page may withhold more than you need — that is a W-4 choice, not something the paycheck math here can see.

What to do with a new job offer

Enter the offer as annual salary, pick the status you will actually put on the W-4, and add only dependents you will claim. Compare weekly versus biweekly if the offer letter is silent; frequency changes the size of each check, not the annual federal tax in this model (except rounding). Then subtract state tax and benefits from a similar stub if you have one. For the official form, use the IRS Tax Withholding Estimator and IRS Publication 15-T. This page is educational, not advice on how to fill a W-4.