How to use the W-4 calculator
- Have your latest pay stub ready. Enter how often you’re paid, your taxable pay per paycheck, and how many paychecks are left this year. The year-to-date pay and federal tax withheld make the projection exact; without them the calculator assumes every paycheck was the same.
- Tell it what your W-4 says now, if it has more than your filing status on it, or type the tax withheld from your latest paycheck.
- Add other jobs and income: a second job, your spouse’s pay on a joint return, interest and dividends, estimated tax payments.
- Add deductions and children. Tips, overtime, car loan interest and the senior deduction are the new ones for 2026; itemized deductions only if they beat the standard deduction.
- Read the projected refund or balance due, then copy the suggested W-4 entries onto a new Form W-4 and give it to your employer.
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How withholding is worked out
Employers with payroll software use the IRS percentage method in Publication 15-T. For 2026 it takes your pay times the number of paychecks a year, adds Step 4(a) and subtracts Step 4(b) plus a built-in $12,900 for married filing jointly or $8,600 otherwise (nothing if the Step 2 box is checked), looks the result up in the yearly rate table for your filing status, divides by the number of paychecks, subtracts Step 3 divided the same way, and adds Step 4(c). The calculator does exactly that, and shows each line under “How your employer figures it”.
With one job all year and a W-4 that only gives your filing status, the tables withhold close to your actual tax. The gap comes from what the tables can’t see: a second job, a spouse’s pay, interest and dividends, a raise or bonus mid-year, children you didn’t list, or deductions beyond the standard deduction ($16,100 single, $32,200 married filing jointly, $24,150 head of household for 2026).
Reading the result
The projected tax is your 2026 federal income tax after credits, using the 2026 brackets. The child tax credit is $2,200 per child under 17 and $500 for each other dependent, reduced by $50 for every $1,000, or part of $1,000, of income over $200,000 ($400,000 joint); up to $1,700 a child can be paid out even when it is more than your tax. Projected withholding is what has been withheld so far, plus the paychecks left at the current rate, plus other jobs and estimated payments.
The suggested W-4 puts your credits in Step 3, other income in Step 4(a) and extra deductions in Step 4(b), as the form’s own worksheets do, then sizes the rest for the paychecks left: an extra amount in Step 4(c) if you’d owe, or a larger Step 3 if you’d get a big refund. The amounts are rounded so the result lands on a small refund rather than a small bill.
A refund isn’t a bonus: it is your own money the government held without interest. A big balance due can bring an underpayment penalty. Aiming for close to zero means more in each paycheck without a surprise in April.
When to check your withholding
After a new job, a raise, marriage or divorce, a new child, a second job or a spouse who starts working, and every January, because a W-4 sized to catch up this year will over-withhold next year. The 2026 form also has a new worksheet for the tips, overtime, car loan and senior deductions from the 2025 tax law: the no tax on tips calculator and the no tax on overtime calculator check whether yours qualify, and the SALT deduction calculator works out whether you itemize. To plan around pay dates, the pay period calendar lists every payday of the year.
Sources, checked October 25, 2026: IRS, Publication 15-T (2026), Worksheet 1A and the 2026 Percentage Method Tables for Automated Payroll Systems; IRS, Form W-4 (2026), Step 3 and the Step 4(b) Deductions Worksheet; Rev. Proc. 2025-32 (2026 brackets, standard deductions, child tax credit); IRS, Schedule 8812 (2025) and its instructions (the credit’s phase-out and refundable part); IRS, Publication 505 (2026); Pub. L. 119-21. For cases this calculator leaves out, use the IRS Tax Withholding Estimator.