How the Marriage Tax Calculator Works
How the Marriage Tax Calculator Works
When two people marry, they usually file one joint tax return instead of two single ones. That can change the total tax they pay. Sometimes the couple pays less, which is called a marriage bonus. Sometimes they pay more, which is called a marriage penalty. The Marriage Tax Calculator compares the two situations for your incomes, using U.S. federal income tax rules.
What you enter
- Your income before tax: your yearly income.
- Your partner's income before tax: their yearly income. Use 0 if they have none.
How the tax is worked out
The calculator does the same steps twice. First it works out the tax for each of you as a single filer. Then it works out the tax for the two of you together, as a married couple filing jointly. Each time it does this:
taxable income = income - standard deduction tax = each slice of taxable income x the rate for that slice
Federal income tax is progressive. The first slice of your taxable income is taxed at 10%, the next at 12%, and so on, up to 37%. Only the part of your income that falls in a higher slice is taxed at the higher rate. The calculator uses the 2025 standard deduction of $15,750 for a single filer and $31,500 for a married couple filing jointly, and the 2025 tax brackets.
marriage effect = joint tax - (your single tax + your partner's single tax)
If the result is above zero, that is a marriage penalty. If it is below zero, that is a marriage bonus.
Why a penalty or bonus happens
- Bonus: When one spouse earns much more than the other, the joint return lets the lower-earner's unused low brackets and deduction soak up part of the higher earner's income. The higher earner would have been taxed at a higher rate alone.
- No change: For most of the lower and middle brackets, the joint brackets and deduction are exactly double the single ones. So two similar earners in the middle see no difference.
- Penalty: At the top, the joint brackets are not twice as wide as the single ones. Two high earners with similar incomes can end up in a higher bracket together than they would be alone.
Worked examples
| Your income | Partner's income | Two single returns | Joint return | Result |
|---|---|---|---|---|
| $120,000 | $40,000 | $20,539 | $18,098 | Bonus of $2,440 |
| $150,000 | $0 | $25,067 | $15,898 | Bonus of $9,169 |
| $75,000 | $75,000 | $15,898 | $15,898 | No difference |
| $400,000 | $400,000 | $208,070 | $208,408 | Penalty of $338 |
In the first row, you pay $17,867 on your own, and your partner pays $2,672. Together, filing jointly, you pay $18,098, which is $2,440 less. Your top rate as a single filer is 24%, and jointly it is 22%.
Chart: the same income, split differently
The calculator also shows what happens to the same combined income of $160,000 when it is divided differently between the two of you. The bars show the bonus in dollars. The more unequal the split, the bigger the bonus. At an equal split, there is none:
100 / 0 ████████████████████████████████████████ $9,369 bonus 90 / 10 ███████████████████████ $5,554 bonus 80 / 20 ██████████████ $3,400 bonus 70 / 30 ███████ $1,622 bonus 60 / 40 (about $22 bonus) 50 / 50 (no difference)
Good to know
- Under current rules, the marriage penalty is small and mostly affects couples with very high incomes. Most couples get a bonus or no change.
- Filing separately as a married couple is another choice, but it usually costs more in tax and gives up some credits. This calculator compares single with joint filing.
- Some credits, and benefits based on income, can change a lot when you marry. Examples are the earned income credit, student loan repayment plans and health insurance subsidies. They are not included here.
- Marriage is a big decision that rarely depends on tax alone.
What this calculator does not include
- State and local income tax, which have their own rules.
- Social Security and Medicare tax, which do not change when you marry.
- Tax credits, itemized deductions, retirement contributions, capital gains and other special income.
- Changes to the tax law. The figures are for 2025. Check irs.gov for the current year.
This tool gives an estimate for general information only. It is not tax advice. For your own situation, talk to a qualified tax professional.