How this calculation works
The calculator applies the IRS 2026 standard deduction and marginal bands for each modeled filing status. It reports the joint result beside the two single counterfactuals and the sum of separate married returns.
Marriage difference = joint tax on combined ordinary income − sum of the two hypothetical single taxes.A worked example
At 100,000 and 30,000 of ordinary income, the modeled separate single taxes sum to 14,590. The joint tax is 11,240, a modeled difference of −3,350.
Good to know
Educational federal ordinary-income scenario only. It assumes standard deductions and excludes credits, payroll tax, capital gains, state taxes and special rules. Confirm filing eligibility and actual tax with the IRS or a qualified adviser.
Reference: IRS Revenue Procedure 2025-32, 2026 deductions and rates (opens in a new tab) ↗
How the inputs affect the result
Keep the income amounts fixed while comparing filing status. Real households may have deductions or credits that change with filing status, so a difference from this narrow model can be larger or smaller on an actual return.
Equal income provides a contrasting ordinary-income scenario.
Where the calculation applies
Educational federal ordinary-income scenario only. It assumes standard deductions and excludes credits, payroll tax, capital gains, state taxes and special rules. Confirm filing eligibility and actual tax with the IRS or a qualified adviser.
For a related calculation, see the US federal income tax calculator 2027.
Read more: IRS Revenue Procedure 2025-32, 2026 deductions and rates (opens in a new tab) ↗
A few questions, answered
Can spouses select single filing because that scenario costs less?
Use the single result as a hypothetical comparison. Actual filing status follows IRS rules for your circumstances.
What does the “Equal income split” setting illustrate?
Equal income provides a contrasting ordinary-income scenario.