Conditional federal ordinary-income comparison for 2025 or 2026, using the basic standard deduction and nonrefundable Child Tax Credit only. It assumes neither adult is age 65 or older, blind or another taxpayer’s dependent. Preferential capital-gain rates, itemized deductions, AMT, QBI, EITC, ACTC, other credits, payroll and state taxes are excluded. Two single returns are a hypothetical unmarried comparison, not an election available to a married couple. Head-of-household eligibility is not modeled. A modeled difference does not determine whether to marry or how an actual return may be filed.
Why marriage changes your tax at all
Single and MFJ band widths differ. The table and bars use each return’s own taxable-income bounds, not one shared dollar range. Credit effects are shown separately. Enter each partner’s total that is independently allowed in every scenario shown. Adjustment eligibility and filing-status restrictions are not determined here. Do not enter the standard deduction or count an adjustment twice.
The bonus: one earner carries the household
A joint return can use bracket capacity that a lower-income partner would not use on a hypothetical single return. The size of the modeled benefit depends on the entered incomes, allowed adjustments and child-credit allocation; it is not a universal rule that a wider income gap always produces a larger bonus.
The neutral middle: two similar incomes
Equal incomes can produce a tie within this limited comparison. Use the actual dated tables and receipts rather than assuming every joint bracket is exactly twice the single bracket. This does not establish how frequently real households have a bonus or penalty.
The penalty: two high earners at the top
At higher taxable incomes, some joint thresholds are less than twice the corresponding single thresholds, which can create a modeled penalty. Other real-return deductions, credits and taxes can also change a marriage comparison; this calculator excludes those components as disclosed.
Children, credits, and what this leaves out
Count only children eligible for the nonrefundable Child Tax Credit in the modeled scenarios, including age, relationship, residence, support and identification requirements. Each child is assigned once; no names, birth dates or SSNs are collected. Partner B receives the remaining children. Blank retains the previous rule: the higher adjusted-income partner claims all children, with Partner A on a tie.