How the comparison works
Each partner's unmarried tax is figured on income − adjustments − the basic standard deduction for their status ($16,100 single or $24,150 head of household in 2026). The joint return uses combined income − combined adjustments − the $32,200 joint standard deduction. Each taxable income is run through the 2026 bracket schedule; the difference is the marriage penalty (positive) or bonus (negative).
Most joint brackets are exactly twice the single ones up to the 35% bracket, so couples with similar incomes often see little change. Couples with very different incomes usually get a bonus, and two high earners can hit a penalty where the joint 37% threshold ($768,700) is less than twice the single one ($640,600).
Worked example
Partner 1 earns $90,000 and partner 2 $60,000. Single returns: taxable $73,900 → $10,970 and $43,900 → $5,020, total $15,990. Joint: $150,000 − $32,200 = $117,800 taxable → $15,340. The couple saves $650, a marriage bonus.
What is not included
Credits such as the child tax credit and earned income credit, capital gains rates, itemized deductions, the extra standard deduction at 65 or for blindness, state taxes and payroll taxes are not modeled. Credits in particular can create penalties this estimate does not show.