W-4 Withholding Calculator
With tax you expect to owe for the year 9000 usd, federal tax withheld so far 3000 usd, withheld each paycheck now 500 usd, paychecks left this year 12, w-4 withholding comes to $0.00 — extra to add on line 4(c). It is reached in 7 steps, the last of which is max(0, 0) / 12, and each one is printed on the page with its numbers filled in. The formula is the one published by IRS, not an approximation fitted to it.
What to put on line 4(c) of a W-4 to land where you want in April — or what to stop withholding if the refund is too big.
Formula and sources checked · How we check
Tax you expect to owe for the year 9000, Federal tax withheld so far 3000, Withheld each paycheck now 500, Paychecks left this year 12
$0.00
Extra to add on line 4(c) for the example below. Editing a field recomputes the calculator below; this figure holds the answer the page was loaded with.
It is written into the HTML rather than drawn by a script, so a search engine reading this page without running JavaScript still finds an answer.
- Total to have withheld by year end
9000 + 0 * 10009,000- On course to withhold
3000 + 500 * 129,000- Short by
9000 - 90000- Extra to add on line 4(c)
max(0, 0) / 120- Or, if over-withholding, the amount a paycheck could stop losing
max(0, -0) / 120- New withholding a paycheck
500 + 0500- Owed in April if nothing changes
9000 - 90000
Worked example
$3,000 withheld and twelve paychecks of $500 to come is $9,000 — exactly the tax expected, so line 4(c) stays empty. Miss one of those paychecks and the same sum leaves $500 owed, which is the sort of gap this is for.
How to work it out yourself
- 1.Take the tax you expect to owe from last year’s return unless something has changed. A raise, a bonus, a second job, a spouse starting work or a child ageing out of the credit all change it.
- 2.Read year-to-date withholding off your latest pay stub, and the per-paycheck figure from the same stub.
- 3.Count the paychecks actually left in the year, not the months. Twenty-six biweekly periods means some months have three.
- 4.Put the answer on line 4(c) of a new W-4 and give it to payroll. Withholding is treated as paid evenly across the year however late it was withheld, which is why raising it in November still cures an underpayment from March.
The formula
- Total to have withheld by year end
9000 + 0 * 1000 - On course to withhold
3000 + 500 * 12 - Short by
9000 - 9000 - Extra to add on line 4(c)
max(0, 0) / 12 - Or, if over-withholding, the amount a paycheck could stop losing
max(0, -0) / 12 - New withholding a paycheck
500 + 0 - Owed in April if nothing changes
9000 - 9000
Source: IRS — About Form W-4: line 4(c) is extra withholding per pay period, IRS — tax withholding estimator and the safe harbour rules
Questions people actually ask
- What is line 4(c) on the W-4?
- Extra tax to withhold from each paycheck, on top of what the tables produce. It is the only field on the form that moves withholding by a flat, predictable amount, which makes it the one to use when you know the size of the gap rather than the reason for it.
- Why do I owe tax when I have a job that withholds?
- Usually a second income the tables cannot see. The withholding tables assume the job in front of them is your only one, so two jobs, a working spouse, freelance income or investment income each leave a gap. A bonus withheld at the flat 22% supplemental rate does the same to anyone whose real bracket is higher.
- Is it better to break even or to get a refund?
- Breaking even keeps your money through the year; a refund is an interest-free loan to the government repaid in one instalment. Whether that is bad depends on whether you would otherwise have spent it — the argument that it is always a mistake assumes a discipline not everyone wants to rely on. What is worth knowing is that it is a choice, changed on one line of a form.
- Can I fix an underpayment late in the year?
- Withholding can, and estimated payments cannot. Tax withheld from wages is treated as paid evenly across the year whenever it was actually taken, so raising line 4(c) in November cures a shortfall from March. A quarterly estimated payment is credited when it is made, so a large December payment does not undo a short April one.
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