Frequently asked questions
How does this tool calculate your withholding?
It first annualizes your gross pay based on the frequency you chose. To that annual amount it adds the Step 4(a) other income, subtracts the Step 4(b) deductions and a fixed adjustment based on filing status (or uses a different table if you checked Step 2), applies the federal tax brackets, subtracts the annual Step 3 credit, and divides by the number of pay periods in the year; it then adds the Step 4(c) extra withholding per period. Separately, it calculates Social Security and Medicare on the period's gross pay, and if you picked a covered state, it applies that state's own withholding formula the same way: annualize, subtract its deduction, apply its rate, and divide back down.
What does this calculation leave out?
It does not subtract pre-tax deductions such as a 401(k) or a section 125 health plan (these do lower the real base in actual payroll); it does not include local city or county taxes; it does not calculate mandatory state disability or paid-leave programs; it does not use the special method for bonuses or supplemental pay; it does not support a pre-2020 W-4 (the allowances version) or exempt status; and it assumes you live in the same state where you work.
Which states does this calculator cover, and why not all of them?
We only include a state when its official 2026 employer guide reduces to annualizing the salary, subtracting a fixed amount based on filing status, applying a flat rate or brackets, and dividing back by the pay periods — without needing the number of exemptions or allowances on your state certificate. It currently covers Alaska, Colorado, Florida, Georgia, Kentucky, Louisiana, Mississippi, Nevada, New Hampshire, North Carolina, Pennsylvania, South Dakota, Tennessee, Texas, Washington and Wyoming. For those states we assume your state withholding certificate uses the same filing status as your federal W-4, with no extra allowances; in Georgia and Mississippi, the married filing status option also assumes only one spouse has income. States with progressive taxes and allowance-based credits, or with a mandatory local tax built into the same form, are left out for now.
What are Steps 2, 3 and 4 of the W-4?
Step 2 is a checkbox you mark only when there are exactly two jobs in total (you with two, or you and your spouse with one each); checking it makes your employer withhold using a different, higher table. Step 3 is the annual dollar amount you claim for qualifying children, other dependents, or other credits, and it lowers your withholding. Step 4 has three parts: 4(a) for other annual income that is not from a job, 4(b) for deductions other than the standard deduction, and 4(c) to ask for a flat extra amount withheld from every paycheck.
Why might my result differ by a few cents from another calculator, and is Social Security always withheld?
Social Security stops being withheld for the year once your year-to-date wages reach the annual cap (this tool flags it if your current payment gets you close to that cap); Additional Medicare, on the other hand, starts being withheld above a flat threshold that is the same for every filing status — withholding does not look at your filing status or your spouse's pay; the actual tax is settled on your return with Form 8959, where your filing status and combined income do count. On top of that, your employer may round federal withholding to the nearest whole dollar per IRS guidance; the one-cent difference from Pub 15-T usually comes from rounding the annual tax before dividing it by the pay periods. Of the states we cover, North Carolina and Mississippi are the only ones where state withholding is always rounded to the whole dollar.