Marriage Tax Penalty Calculator

• Works out federal income tax for each of you as an unmarried filer and for the two of you as a married couple, using the 2026 brackets and standard deductions from the site's tax data.
• Includes the 3.8% Net Investment Income Tax and the 0.9% Additional Medicare Tax, whose thresholds are not doubled for married couples.
• Handles head of household status, long-term gains and the age-65 senior deduction, and shows married filing separately alongside.
• Shows how the penalty or bonus changes when the same total wages are split differently between the two of you.

How to use this calculator

Enter each partner's wages and salary, and how each of you would file if you stayed unmarried: single, or head of household if you have a qualifying child or relative. That is enough for most couples.

Open Advanced to add interest and other ordinary income, long-term capital gains and qualified dividends, pre-tax deductions such as a traditional IRA or HSA, and whether either of you is 65 or older. The result compares total federal tax on two unmarried returns, one joint return and two married-separate returns, and gives the marriage penalty or bonus in dollars.

What the marriage penalty and bonus are

A marriage penalty is extra federal tax a couple pays because they are married, compared with what the same two people would pay as unmarried filers. A marriage bonus is the opposite: a lower bill after marriage.

Which one you get depends mostly on how evenly your incomes are split. Joint brackets are twice as wide as single brackets for most of the income range, so when one partner earns most of the money, the joint return lets that income fall into lower brackets and the couple gets a bonus. When both partners earn similar amounts, doubling the brackets changes little, and any threshold that is not doubled becomes a penalty.

Penalties used to be far more common. Before 2001 the joint standard deduction and the lower brackets were less than twice the single amounts, so two similar earners almost always paid more after marrying. Laws passed in 2001 and 2017 doubled the joint figures for nearly all brackets, and the One Big Beautiful Bill Act kept that structure for 2026 and later. What remains are the items that were never indexed or doubled: the top brackets, the two 2013 Medicare-related taxes, and a number of credits and phase-outs that this calculator lists but does not model.

Where the 2026 tax code is not doubled

• The 35% bracket. For 2026 the joint brackets are exactly twice the single brackets up to the top of the 32% bracket ($256,225 single, $512,450 joint). The 35% bracket ends at $640,600 for a single filer but $768,700 for a couple, far less than double.
• Additional Medicare Tax. An extra 0.9% applies to wages above $200,000 for a single filer but above $250,000 of the couple's combined wages on a joint return, and above $125,000 each on separate returns. Employers withhold it only on pay above $200,000 per person, so a couple can find it owed when they file.
• Net Investment Income Tax. The 3.8% tax on interest, dividends, gains and rents applies above $200,000 of modified AGI for a single filer and $250,000 for a joint return. These thresholds are set in law and have not risen with inflation since 2013.
• Head of household. A single parent filing as head of household has wider brackets and a $24,150 standard deduction. Once married, that status is gone.
• The senior deduction. The temporary $6,000 deduction for people 65 and older starts to phase out at $75,000 of modified AGI for a single filer but $150,000 for a couple, and married people filing separately cannot claim it at all.

How the comparison is calculated

Unmarried     = tax on partner A's return + tax on partner B's return
Married joint = tax on one return with combined income
Each return   = income tax (brackets, capital gains rates)
              + 3.8% NIIT above the threshold
              + 0.9% Additional Medicare Tax on wages above the threshold
Penalty (+) or bonus (-) = married joint - unmarried

Income tax uses the same engine as our other 2026 tax calculators. Regular Social Security and Medicare tax (7.65% of wages) is the same whether you are married or not, so it is left out of the comparison.

A worked example

With the calculator's starting values, partner A earns $220,000 and partner B $180,000, both filing as single. Unmarried, A's federal tax is $41,884 and B's is $31,934. Married filing jointly, the couple owes $74,818, so marriage brings a penalty of $1,000. Their income tax is slightly lower on the joint return, but the Additional Medicare Tax now applies to $150,000 of combined wages rather than $20,000 of A's.

The split matters. The same $400,000 in wages produces a $30,116 bonus if one partner earns it all, and a $1,350 penalty if each earns half.

Other couples: one partner earning $100,000 and the other nothing gets a bonus of $5,530. Two partners earning $100,000 each see no change, because the brackets they use are exactly doubled. Two partners earning $600,000 each pay a penalty of $9,332, from the 35% bracket and the Medicare threshold. A single parent earning $60,000 as head of household who marries a partner earning the same pays a penalty of $1,072.

Investment income adds to it. Two partners each earning $190,000 in wages and $30,000 in interest pay a penalty of $1,930: on a joint return the Additional Medicare Tax applies to $130,000 of wages and the Net Investment Income Tax to all $60,000 of interest, and neither threshold is doubled. Two 65-year-olds earning $90,000 each see a penalty of $572.

What couples can do about a penalty

You cannot choose to file as single once you are married, but a few choices change the size of a penalty:

• Pre-tax savings. Traditional 401(k), 403(b), IRA and HSA contributions lower taxable income on a joint return just as they do on single returns, and they can keep modified AGI under the Net Investment Income Tax threshold.
• Timing investment income. Spreading large capital gains over several years, or harvesting losses, can keep investment income below the 3.8% threshold.
• Withholding. Each spouse should complete a new Form W-4, using the IRS Tax Withholding Estimator or the two-jobs checkbox, so the combined withholding covers the joint bill, including any Additional Medicare Tax.
• Itemizing together. A couple can combine mortgage interest, charitable gifts and state and local taxes on one return, which can make itemizing worthwhile when neither could alone.

The tax result should not decide whether to marry. Marriage also affects Social Security spousal and survivor benefits, health coverage, inheritance rights and estate tax, where married couples gain an unlimited marital deduction and can share their exemptions.

Does filing separately help?

Married filing separately rarely beats a joint return. Its brackets are half the joint brackets, so it does not undo the penalty, and separate filers lose or have reduced access to the earned income credit, education credits, the child and dependent care credit, the senior deduction and other benefits. It can still make sense in narrow cases: to keep one spouse's tax liability separate, or when income-driven student loan payments are based on one spouse's income. The calculator shows it so you can see the gap, but only for the taxes it models.

Assumptions and limitations

• Federal only, 2026. State income taxes can add their own marriage penalties or bonuses.
• Standard deduction. Itemized deductions are not modelled. The 2026 SALT cap of $40,400 is the same for a single filer and a married couple, which is a penalty for two homeowners who itemize, and it is not included.
• No credits. The earned income credit, child tax credit, child and dependent care credit and education credits are left out. The earned income credit in particular can create large penalties for lower-income couples with children.
• Wages, interest and gains only. Self-employment income, the qualified business income deduction and the AMT are not modelled.
• Other rules tied to marriage. Health insurance premium credits, income-driven student loan payments and the taxation of Social Security benefits also change with marriage and are outside this tool.

Common mistakes

Comparing take-home pay from paychecks. Withholding tables assume each job is the only one. Two earners who marry often need to update their W-4s to avoid a bill in April.

Missing the Additional Medicare Tax. No employer withholds it below $200,000, so a couple each earning $150,000 owes it on $50,000 of wages with nothing withheld.

Assuming the date in the year matters. Your filing status depends on whether you are married on December 31, so a December wedding counts for the whole year.

Forgetting credits. For lower and middle incomes with children, the credits this calculator leaves out can matter more than the brackets.

Frequently asked questions