What the calculator shows
Enter each spouse’s employment wages before traditional pre-tax 401(k) or 403(b) salary deferrals, then add filing status, those deferrals, deductions, nonrefundable credits and an optional annual state/local tax amount. The result separates federal income tax, Social Security and Medicare, then shows annual and pay-period averages.
Calculation method
Taxable income equals combined pre-deferral employment wages minus entered traditional 401(k)/403(b) deferrals and the selected 2026 standard or itemized deduction. Federal income tax uses the seven statutory marginal bands. Social Security and Medicare use the pre-deferral wages because those traditional salary deferrals remain part of their wage bases.
Inputs to confirm
Use gross pay and traditional 401(k)/403(b) payroll elections. Form W-2 Box 1 helps reconcile federal wages after those deferrals. Enter state and local income tax as an annual amount when it belongs in the take-home comparison, then match withholding and filing amounts to Form W-4, pay statements, Form W-2 and the filed return.
Worked example
For a single employee earning $85,000 before any traditional salary deferral, the 2026 standard deduction is $16,100 and taxable income is $68,900. The estimate is $9,870 of federal income tax, $5,270 of Social Security and $1,232.50 of Medicare. With no state or local tax entered, estimated take-home pay is $68,627.50 a year, $5,718.96 a month or $2,639.52 per biweekly pay period.
Input variations
| Scenario | Taxable income | Federal tax | FICA | Estimated take-home |
|---|---|---|---|---|
| $85,000, single | $68,900 | $9,870 | $6,502.50 | $68,627.50 |
| Same wages, $5,000 traditional deferral | $63,900 | $8,770 | $6,502.50 | $64,727.50 after the deferral |
| $85,000 + $60,000, married filing jointly | $112,800 | $14,240 | $11,092.50 | $119,667.50 |
The traditional deferral lowers federal taxable income but not the Social Security or Medicare wage base. The take-home comparison also subtracts the amount contributed.
Differences from official documents
This is an annual liability estimate, not an IRS withholding table or a completed return. It does not automatically calculate state tax, refundable credits, self-employment tax, capital gains, other income, above-the-line deductions or itemized-deduction details. In particular, the temporary deductions for qualified tips, qualified overtime, eligible seniors and qualifying new-car loan interest are not modelled. A pay statement can also differ because payroll works one period at a time and tracks year-to-date limits.
Thresholds and limits
The 2026 standard deductions used here are $16,100 for single or married filing separately, $32,200 for married filing jointly and $24,150 for head of household. Social Security is 6.2% per employee up to $184,500 of wages; Medicare is 1.45%, plus 0.9% above the filing-status threshold. Nonrefundable credits cannot reduce modeled federal income tax below zero.
Documents to check
Check gross wages and traditional 401(k)/403(b) elections on pay statements, federal wages in Form W-2 Box 1, Social Security and Medicare wages in Boxes 3 and 5, filing choices on Form W-4, and the final figures on Form 1040. Use the relevant state return or withholding record for the optional state/local amount.
Read the estimate like a tax return, not a single tax rate
The useful comparison is not gross pay multiplied by one percentage. Federal income tax, payroll taxes, salary deferrals and state or local tax use different bases, so the result keeps them separate.
Marginal brackets do not tax every dollar at the top rate
After the selected deduction, each slice of taxable income is charged at its own 2026 rate. Moving into a higher bracket changes the rate on the next dollars, not the rate on all earlier income. Nonrefundable credits then reduce calculated federal income tax but cannot create a negative tax result here.
Federal wages and FICA wages are not always the same
Traditional 401(k) or 403(b) salary deferrals reduce the federal taxable-income path in this model, but they remain in Social Security and Medicare wages. Social Security is capped for each employee, which is why spouses enter wages separately; Medicare and Additional Medicare use their own combined thresholds.
Use the result to reconcile, not predict withholding
Compare gross pay and deferrals with pay statements, federal wages with Form W-2 Box 1, Social Security and Medicare wages with Boxes 3 and 5, and filing choices with Form W-4. The annual estimate does not reproduce payroll timing, refundable credits, dependants or a state return.
| Record | Use it for | Do not assume |
|---|---|---|
| Pay statement | Gross pay, deferrals and year-to-date withholding | One pay period equals annual liability |
| Form W-2 | Federal, Social Security and Medicare wage bases | Box 1 is the pre-deferral input |
| Form 1040 and state return | Final income, deductions, credits and tax | This calculator replaces a filed return |