Paycheck guides
Allowances disappeared in 2020 and never came back. The form that replaced them is more literal — and if your refund keeps arriving too large, it is the only lever that fixes it.
For decades the W-4 asked how many allowances you claimed, and nobody could explain what an allowance was. The redesigned form dropped them entirely. It now asks for dollar amounts and yes-or-no facts, and your employer feeds those directly into a calculation.
The result is a form that is easier to fill in correctly and much easier to get wrong through neglect — because most people complete it once on their first day and never look at it again.
Payroll withholding works by annualising. Your employer takes the current cheque, multiplies it by the number of pay periods in the year, and asks: if this were the whole year, what would the tax be? Then it divides that answer back down to one period.
This is why a single large cheque is over-withheld and why starting a job in October means you are usually over-withheld for the rest of the year — the system assumes you have been earning at that rate all along.
Filing status sets the standard deduction the calculation assumes: $16,100 for single or married filing separately in 2026, $32,200 for married filing jointly, $24,150 for head of household. It also sets which bracket table applies. This is the single largest lever on the form, and the one most likely to be stale after a marriage or divorce.
The step people skip, and the one that causes most underpayment. Each employer assumes it is your only source of income, so each applies the full standard deduction and starts you at the bottom of the bracket table. Two jobs at $50,000 each are withheld as though you earn $50,000 twice, not $100,000 once.
Ticking the box in Step 2(c) on both W-4s tells each employer to withhold at roughly half the standard deduction and shifted brackets. It only works properly when the two jobs pay similar amounts; for uneven incomes the worksheet or the IRS Tax Withholding Estimator gives a better answer.
Here you enter a dollar amount, not a count. The credit amounts are entered directly and reduce your withholding for the year by that amount, spread across your remaining pay periods. Enter it on only one job’s W-4 if you have more than one, or you will claim the same credit twice.
Three independent fields that do most of the fine-tuning:
An unsigned W-4 is invalid. If you never file one at all, your employer must withhold as single with no adjustments, which is usually the highest rate available.
A refund is not a bonus. It is the return of money you lent the government at zero interest for up to sixteen months. A $3,600 refund is $300 a month you could have had as you earned it.
The opposite failure costs more. Underpay by enough and you face an underpayment penalty, charged as interest on the shortfall. The safe harbours: you generally avoid the penalty if you pay at least 90% of the current year’s tax, or 100% of last year’s (110% if your prior-year adjusted gross income exceeded $150,000).
A rough correction, if your situation was stable last year: divide last year’s refund by the number of pay periods left, and add that figure to Step 4(c) as a negative — meaning reduce it — or claim the equivalent in Step 4(b). If you owed instead, add the amount to 4(c). Then check again after two cheques.
You can file a new W-4 whenever you like; employers must apply it by the start of the first payroll period ending 30 or more days after you hand it in. Changes made now affect only the cheques still to come, so a correction in September has three months to work rather than twelve.
Sources: IRS Form W-4 and instructions; IRS Publication 15-T, Federal Income Tax Withholding Methods; IRS Revenue Procedure 2025-32 for 2026 standard deduction amounts; IRS Publication 505 on estimated tax and underpayment penalties.
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