How to use this calculator
This calculator answers: What actually lands in my bank account each payday, and is my W-4 withholding on track?
Why this matters: If you don’t know what actually lands in your account or whether your withholding is on track, you’re either giving the IRS a free loan or risking an underpayment surprise.
- On the Paycheck tab: enter Gross annual salary ($), pay frequency, filing status, 401(k)/403(b) and HSA contributions, health premiums, and your state income tax rate.
- Everything recalculates live as you type. Switch to the “W-4 tuner” tab to model W-4 steps (multiple jobs, dependent credits, other income/deductions, extra withholding) and see the projected refund or balance due.
- Read “Your paycheck”: net pay per payday, “Where each paycheck goes”, and your annual refund or amount owed. Try adding $50 of extra withholding per paycheck in the W-4 tuner to watch the refund move dollar for dollar.
Your paycheck inputs
How the math works
- Annualized wage method (the IRS Publication 15-T percentage method, simplified): your per-paycheck taxable wages are annualized, the 2026 standard deduction is subtracted, 2026 federal brackets are applied, Step 3 credits reduce the bill, and the result is divided back across your pay periods — plus any Step 4(c) extra withholding.
- W-4 Step 2 (multiple jobs) is approximated by halving the standard deduction and every bracket threshold, which is roughly what the IRS tables do behind the checkbox.
- FICA is annualized on FICA wages — gross salary minus payroll HSA contributions and health premiums, which are assumed to run through a qualifying cafeteria (Section 125) plan. Traditional 401(k) elective deferrals lower federal and state taxable wages but are still FICA wages, so they don't reduce Social Security or Medicare here. Rates: 6.2% Social Security on wages up to the 2026 wage base of $184,500, 1.45% Medicare on everything, plus 0.9% additional Medicare over $200k single / $250k joint.Sources: SSA, contribution and benefit base · IRS, Topic 560 (Additional Medicare Tax)
- The tuner compares your projected annual withholding (same inputs) with your projected actual liability and backs into the Step 4(c) dollar amount that closes the gap.
Frequently asked questions
What does the W-4 Step 2 checkbox do?
The Step 2 checkbox tells your employer you have more than one job (or a working spouse), so it withholds as if your standard deduction and tax brackets were cut in half. That prevents the under-withholding that happens when two incomes are each taxed as if they were your only income. This calculator approximates it by halving the standard deduction and bracket thresholds.
Why was my bonus taxed so much more than my salary?
Bonuses are "supplemental wages" and employers usually withhold a flat 22% federal (37% over $1 million) rather than your regular bracket rate. It often looks like over-withholding, and you get the difference back at tax time. This calculator models regular paycheck withholding only.Source: IRS, supplemental wage withholding rates
Is a big tax refund good?
A refund just means you overpaid during the year — you gave the government an interest-free loan. Owing a small amount (under $1,000) is actually the efficient outcome, as long as you can pay it in April and avoid underpayment penalties. The W-4 tuner helps you land near $0.
Why doesn't the calculator ask which state I live in?
Modeling all 50 states' tax codes would make this tool enormously complex. Instead you enter your state's effective flat rate as a single percentage — close enough for a take-home estimate. Nine states have no income tax at all, so you'd enter 0.
I changed jobs mid-year. Is the projection still right?
Only roughly. The tuner annualizes your current paycheck as if it ran all year. Mid-year job changes, raises, or bonuses shift the real numbers — re-run it with your new paycheck after any change.
What's the difference between Step 3 and Step 4(c) on the W-4?
Step 3 (credits for dependents) reduces withholding — it accounts for tax credits like the Child Tax Credit. Step 4(c) (extra withholding) increases withholding by a flat dollar amount per paycheck. They push in opposite directions: Step 3 for money you're owed back, Step 4(c) for catching up.
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Last updated: September 27, 2026