How this number is made
A marriage penalty in the federal income tax is the extra tax from filing jointly instead of as two single people. A bonus is the reverse. The inputs are taxable income, after the standard deduction or itemized deductions. Payroll taxes do not change with the joint return.
- Taxable income is after deductions. Do not type gross wages unless you have already subtracted them.
- The 2026 brackets on this site are the ones used. State tax is not included.
Formula
Joint tax minus the two single taxes. Positive means filing jointly costs more federal income tax.
Worked example
With the figures already in the form, joint tax minus two single taxes is $0.00.
Questions
When does the penalty show up?
Most often when both spouses have similar, high taxable incomes, because the joint brackets are not always twice the single brackets at the top.
What about the standard deduction?
Take it out before you type. The joint standard deduction is larger than one single deduction. If you type gross wages, you will overstate the tax.