Compare your combined federal tax filing jointly vs. as two singles to see if you have a marriage penalty or marriage bonus.
Net effect of marriage
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Total tax filing jointly (MFJ)
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Total tax as two singles
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Your breakdown
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Penalty, bonus, or a wash
Marriage changes your federal tax because the married-filing-jointly brackets are not simply two single brackets stacked together. This tool takes each partner's taxable income, computes the tax each would owe filing single, sums those, and compares the total to the tax on their combined income run through the 2026 MFJ brackets. When the joint result is higher, you have a marriage penalty. When it is lower, you have a marriage bonus. The shape of the answer depends almost entirely on how evenly the two incomes are split.
A single earner gets a bonus
Set Partner A to $200,000 of taxable income and Partner B to $40,000, a common situation where one spouse out-earns the other or stays home part of the year. Here is what the calculator returns.
Marriage saves this couple $2,354. The mechanism is that the wider MFJ brackets pull some of Partner A's income down into lower rate bands that Partner B was not fully using. In effect the lower earner's unused bracket room shelters the higher earner's income. This is the typical outcome for single-income households and for couples with a large pay gap, and it is exactly why filing jointly is the default choice for most married taxpayers.
Where the penalty actually appears
Run two equal high earners through the tool and you may be surprised to see a wash. With the 2026 brackets this calculator uses, the MFJ thresholds are exactly double the single thresholds through the 32 percent bracket. The penalty first emerges when combined taxable income exceeds $768,700, where the joint 37 percent bracket starts, while two hypothetical single filers still have room in their 35 percent brackets up to $640,600 each. For equal earners, that crossover is $384,350 each.
To make that concrete, try two partners at $400,000 each in the tool. Filing as two singles their combined tax is about $217,539, while the joint return on $800,000 comes to roughly $218,165, a penalty of about $626. Push both incomes higher and the penalty widens, because more of the combined income is taxed at 37 percent jointly while the two separate filers keep a larger slice in the 35 percent band. The practical takeaway is that the bracket-driven marriage penalty is a concern for dual high earners, not for ordinary middle-income couples, and the further apart the two incomes are, the more likely marriage helps rather than hurts.
Does this tool capture every part of the marriage penalty?
No, and that is worth understanding. This calculator works strictly from taxable income through the ordinary brackets, so it isolates the bracket effect cleanly. The fuller marriage penalty also shows up in places this tool does not model: the 2026 maximum SALT deduction is generally $40,400 for both a joint return and a single return before the high-income phase-down, the net investment income tax thresholds for married couples are less than double the single threshold, and several credits phase out at marriage-unfriendly income levels. Treat the result here as the bracket piece of the story, not the entire bill.
Can we file separately to dodge a penalty?
Almost never successfully. Married filing separately uses brackets that are generally even less favorable than joint, and it disqualifies you from valuable benefits including most education credits, the student loan interest deduction, and the ability to contribute to a Roth IRA at most income levels. Couples occasionally benefit from filing separately for non-tax reasons, such as income-driven student loan repayment or liability separation, but rarely to reduce a bracket-driven marriage penalty. Run both filing statuses through tax software before deciding.