Enter each partner's taxable income to compare filing as two singles against filing jointly, and see the marriage penalty or bonus.
How to Use the Marriage Tax Calculator
Two numbers, one for each partner's taxable income after their own deductions (not gross pay) — that's the whole input surface. Behind those two numbers the calculator quietly runs three separate tax computations: each partner taxed alone, then the same combined income taxed as one joint return, with the gap between them labeled a penalty or a bonus depending on which direction it runs.
Why Similar Incomes Rarely Trigger a Penalty
Married Filing Jointly brackets aren't arbitrary — through the middle of the schedule, they're built by doubling the single-filer thresholds. The 2026 single brackets top out the 10% bracket at $12,400 and the 12% bracket at $50,400; the joint brackets top those same rates at $24,800 and $100,800 — exactly double, both times. Two spouses earning identical or similar incomes each fill up their own single brackets at roughly the same rate a joint return fills up the doubled joint brackets, so the combined tax bill comes out close to identical either way. Run $90,000 and $90,000 through this calculator and the difference lands at zero.
The Top Bracket Is Where the Penalty Actually Lives
The doubling breaks down at the very top of the schedule. The single-filer 35% bracket caps at $640,600 — double that and you'd expect a joint cap of $1,281,200. The actual 2026 joint cap is $768,700, nowhere close. That gap is a real, checkable design choice in the tax code, not a rounding artifact: a married couple where each spouse individually earns close to $640,600 sees a big chunk of income pushed into the 37% joint bracket at $768,700 that would have stayed at 35% for each of them filing single. That's the marriage penalty in its purest form, and it only bites at high, roughly-equal incomes — modest earners rarely feel it, because the lower brackets really are doubled.
Bonuses Show Up When Incomes Are Lopsided
Flip the income split and the same bracket structure works in the couple's favor. One spouse earning $150,000 and the other earning $20,000, filing jointly, spreads their combined $170,000 across the wide joint brackets as if it were one moderate income — instead of the higher earner alone climbing well into their own upper single brackets while the lower earner's bracket space goes unused. Combined, they pay less jointly than the higher earner would have paid filing single at $150,000 plus whatever the $20,000 earner owed on their own. The wider the income gap between two partners, the larger this bonus tends to run.
Put the two effects together and there's a pattern worth remembering: similar incomes trend toward a wash, a large income gap trends toward a bonus, and very high, similar incomes are the one combination reliably worth checking for a penalty before assuming joint filing is automatically better.