W-4 Withholding Calculator
↻ Updated 2026Estimate the federal income tax withheld from each paycheck for 2026, and see the extra withholding to enter on W-4 line 4c to cover untaxed income and avoid a surprise bill.
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How to read your per-paycheck withholding
This is a target, not a prediction. It's what withholding would be if it landed exactly on your tax — $295 a paycheck on the defaults, 26 times, for $7,670. Your actual payslip will differ, because your employer runs the IRS percentage method rather than this even split. The gap between the two is what shows up in April.
How your paycheck withholding and line 4c amount are calculated
Withholding is a prepayment of a tax that won't be computed until next April. This calculator works backwards from the answer: compute the year's tax, then divide by the number of paychecks.
That's a simplification of what payroll actually does, and an honest one. The IRS percentage method in Publication 15-T annualises each individual paycheck, applies the brackets to that, and divides back down — which produces the same answer for a steady salary and a different one for anything else. Bonuses, overtime, a mid-year raise or a mid-year start all break the equivalence.
taxable income = annual salary − standard deduction annual tax = brackets applied to taxable income base per paycheck = annual tax ÷ pay periods total per paycheck = base per paycheck + extra (line 4c) recommended extra = target ÷ pay periods worked at $75,000 single, 26 pay periods: taxable = $75,000 − $16,100 = $58,900 tax = $7,670 base = $7,670 ÷ 26 = $295
- annual salary
- Your gross salary for the year — salary only — this calculator has no field for bonuses, side income or a second job
- standard deduction
- $16,100 single, $32,200 married filing jointly for 2026 — Rev. Proc. 2025-32; the calculator always applies it — Step 3 and Step 4(b) of the W-4 have no equivalent here
- pay periods
- Paychecks per year — 52, 26, 24 or 12 — biweekly (26) and semi-monthly (24) are different: 26 fortnights, or twice a month
- extra
- Additional withholding you've entered on W-4 line 4c — added to every paycheck; feeds the hero figure directly
- target
- Extra tax you want covered across the year — tax on untaxed side income, or a cushion — drives the recommendation only
- recommended extra
- Target divided by pay periods — the figure the IRS instructions expect on line 4c
Line 4c exists because the rest of the W-4 can only describe your job. Step 2 handles multiple jobs, Step 3 handles dependents and credits, Step 4(a) handles other income and 4(b) handles deductions — but any of them can be wrong in ways the form can't express, and 4c is the flat override: a dollar amount, added to every paycheck, no questions asked. It's the only line on the form that isn't an estimate of something.
The reason it matters is timing. Withholding is treated by the IRS as paid evenly across the year no matter when it happened, which estimated payments are not — so a line 4c increase in November is credited as though it had been paid since January. That property is why some people with side income use withholding rather than quarterly vouchers; the quarterly tax calculator computes the alternative.
Worked examples
Example: $75,000 salary, single, paid biweekly
The calculator's defaults. One job, standard deduction, no extra withholding and no target.
| Annual salarygross | $75,000 |
| Less standard deduction2026 single | − $16,100 |
| Taxable incomewhat the brackets see | $58,900 |
| Estimated annual federal tax$1,240 + $4,560 + $1,870 | $7,670 |
| Base withholding per paycheck$7,670 ÷ 26 | $295 |
| Extra withholding (4c)none entered | + $0 |
| Total per paycheckthe hero figure | $295 |
| Annual federal withheld$295 × 26 | $7,670 |
| Effective rate$7,670 ÷ $75,000 | 10.2% |
$295 a paycheck lands exactly on the year's tax — a $0 refund, which is the arithmetically tidy result. Switch to weekly and it's $148 across 52 checks; monthly and it's $639 across 12. The annual figure never moves. Note the effective rate is 10.2% against a 22% marginal bracket: withholding that felt like "22% of my salary" would be more than double the tax.
Example: covering $6,000 of tax on side income
Same salary and schedule, but a freelance project this year will produce roughly $6,000 of tax that nobody is withholding. Enter $6,000 in the target slider.
| Extra tax you want coveredthe target | $6,000 |
| Spread across 26 paychecks$6,000 ÷ 26 | $231 each |
| Enter on W-4 line 4cwhat the recommendation panel outputs | $231 |
| Per paycheck if 4c is set to $231$295 base + $231 | $526 |
| Annual withheld then$526 × 26 — $6 over target, from rounding to the dollar | $13,676 |
$231 per paycheck covers $6,000 across the year. The panel reports the recommendation; the hero figure at the top still reads $295 until you move the separate "Extra withholding" slider too — the two inputs don't talk to each other. Half a year in, the arithmetic changes: $6,000 across the 13 checks left is $462 each, and the calculator has no field for a mid-year start.
Frequently asked questions
What should I put on W-4 line 4c extra withholding?
Line 4c takes a per-paycheck dollar amount, and the IRS instructions define it as the additional tax you want withheld each pay period — including anything carried over from the Multiple Jobs Worksheet (Form W-4, Step 4c).
The arithmetic is division: the amount you want covered across the year, divided by your remaining paychecks. This calculator's target slider does exactly that — $6,000 over 26 paychecks is $231. Two things it can't know: whether your existing withholding is already right (your employer uses the IRS percentage method, not this even split), and how many paychecks are left. Enter a target in July and the honest divisor is 13, not 26.
Why is there no more allowances on the W-4?
Because the thing an allowance measured stopped existing. Each allowance represented one personal exemption, and the Tax Cuts and Jobs Act set personal exemptions to zero from 2018 while nearly doubling the standard deduction. The arithmetic underneath "claim 2 allowances" had no operand left, so the IRS redesigned the form for 2020 around a five-step process that asks for dollars instead (IRS, FAQs on the 2020 Form W-4).
The replacement is more literal. Step 3 asks for dependent credits in dollars, Step 4(a) for other income, 4(b) for deductions beyond the standard, and 4(c) for a flat extra amount. There is no maximum-withholding setting on the modern form — the closest equivalent is a number in 4c, which is why that line inherited the job that "claiming 0" used to do.
Should I claim 1 or 0 on my W-4?
Neither option is on the form. Allowances were removed in 2020, so a W-4 filed today has no box to put a 1 or a 0 in — a payroll system reading a current form is looking at your filing status, dependents in dollars, and any 4(c) amount.
If a pre-2020 W-4 is still on file, your employer keeps withholding against the allowances it shows until you submit a new one. That's why the question persists: the old lever is still connected for people who never replaced the form. What "claiming 0" meant was "assume I have no offsets" — which is not the same as maximum withholding, and is why filers who claimed 0 with two jobs still owed money. Each job was withholding as though it were your only one, and zero allowances didn't change that.
Can I increase withholding at my job instead of paying quarterly estimated taxes?
Yes, and the mechanism is line 4c. The reason people do it is a timing rule rather than convenience: the IRS treats tax withheld at any point in the year as though it were paid evenly across all four periods, while an estimated payment is credited only to the period it was made in (IRS Publication 505).
The consequence is asymmetric. Discover in November that you've under-withheld all year, raise 4c, and the extra is credited back to April — curing a shortfall an estimated payment made the same day could not. On the defaults, covering $6,000 of side-income tax needs $231 per paycheck across 26, or $462 across the 13 left after June. This works where the W-2 job is large enough to absorb the withholding; a freelancer with a small W-2 and large business income can run out of paycheck before covering the bill.
Why your payslip won't match this figure
This is a simplified model of the IRS Tax Withholding Estimator, and the simplifications all point the same way: it assumes your salary is your whole tax life.
- It isn't the percentage method — Payroll systems use IRS Publication 15-T, which annualises each paycheck individually and applies the brackets to that. For a steady salary all year the two agree. Start mid-year, take a bonus, work overtime or get a raise, and they diverge — the percentage method treats an unusually large check as though every check were that size.
- No dependents or credits — W-4 Step 3 is where the Child Tax Credit and other dependent credits reduce withholding, and this calculator has no field for it. A parent claiming credits will see materially more withheld here than their real W-4 would produce.
- One job, salary only — No second job, no spouse's income, no bonus, no side income. This is the single largest cause of real under-withholding — each employer withholds as though its job were your only income, and applies the whole standard deduction to it — and the page cannot represent it. W-4 Step 2 exists precisely for this.
- The target slider is disconnected from the hero — Entering a target produces a recommendation in its own panel but does not change the per-paycheck figure at the top. To see the combined number you must also drag the separate "Extra withholding" slider, which moves in $10 steps — so the recommended $231 isn't exactly settable there.
- Whole-year assumptions — The division assumes every paycheck of the year is still ahead of you. Any mid-year change — a new job, a new W-4, a raise — makes the correct divisor the number of paychecks remaining, which this tool never asks for.
- ·IRS Rev. Proc. 2025-32 — 2026 inflation adjustments — Tax year 2026 brackets & standard deduction
Rates, brackets and limits here are checked against primary sources. If a number still looks off, email support@realmoneyiq.com and we'll review and fix it.
RealMoneyIQ provides free educational calculators, not financial, tax, investment or legal advice. Results are estimates based on the assumptions you enter and publicly published rates; your actual outcome will differ. Always confirm decisions with a licensed professional who knows your full situation.