Marriage Tax Calculator

Marriage changes how you are taxed, sometimes in your favour and sometimes against it. This calculator takes both spouses' income, retirement contributions, deductions, and state rate, works out the federal, payroll, and state tax two ways, and shows the difference. One column is what the two of you would pay as single filers; the other is what you would pay filing a joint return.

One rule shapes everything: for tax purposes your marital status is set by the last day of the tax year. Marry on 31 December and you are treated as married for the whole year. Divorce on the same date and you are treated as unmarried for the whole year.

Where the bonus and the penalty come from

The mechanism is simpler than the reputation suggests. Through the 10%, 12%, 22%, 24%, and 32% brackets, the married-filing-jointly thresholds are exactly double the single ones. Two people with any split of income inside those bands pay precisely the same tax married or single, which is why the default figures on this page produce a difference of zero.

Two things break that symmetry.

A marriage bonus appears when incomes are unequal. Filing jointly pools the income against one doubled set of brackets, so the higher earner's top dollars effectively fall into the lower earner's unused lower brackets. The extreme case is a single-income couple: on $100,000 and nothing, marriage saves several thousand dollars a year. The wider the gap, the bigger the bonus.

A marriage penalty appears when both earn a lot. The 35% and 37% brackets are not doubled for joint filers, so two high earners are pushed into a higher rate together than either would face alone. Put two people on $600,000 each into this calculator and the joint return costs thousands more than two single ones.

So the rule of thumb holds: single-income and lopsided couples generally gain, and high dual-income couples generally lose. Most couples in the middle see very little either way.

The penalties that are not about brackets

The bracket effect gets the attention, but several thresholds simply fail to double for married couples, and each one is a quiet penalty on two-earner households.

• The state and local tax deduction. The cap is the same figure for a single filer and a married couple, so two people who each could have deducted up to the cap alone share one between them after marrying.
• The net investment income tax. The 3.8% surcharge starts at $200,000 of modified AGI for a single filer but only $250,000 for a couple, not $400,000.
• Additional Medicare tax. The extra 0.9% uses the same $200,000 and $250,000 thresholds, with the same effect.
• Capital loss deduction. The $3,000 annual limit on net capital losses against ordinary income is the same whether you file single or jointly.
• Roth IRA and student loan interest phase-outs. Married ranges are less than double the single ranges, so a couple can lose eligibility that either would have kept alone.

Why couples file jointly anyway

Filing jointly is the default for good reason, and it goes beyond the brackets.

• Credits that separate filers lose. Married filing separately disqualifies you from the Earned Income Tax Credit, both education credits, the student loan interest deduction, and the credit for the elderly and disabled, among others. That alone settles the question for most couples.
• The spousal IRA. You normally need earned income to contribute to an IRA. A joint return lets a working spouse fund an account for a partner with little or no income of their own, which is one of the few ways to keep retirement saving going through a career break. See our IRA Calculator.
• The unlimited marital deduction. Assets passing to a surviving spouse are exempt from federal estate tax without limit, and the deceased spouse's unused exclusion can be carried over to the survivor. For wealthy couples this is worth far more than any annual bracket effect.
• Social Security spousal and survivor benefits. A spouse can claim up to half the worker's benefit, and a widow or widower inherits the larger of the two payments for life. Neither is available to an unmarried partner. Our Social Security Calculator covers the claiming decision.

When filing separately makes sense

Married filing separately usually costs more, which is why this calculator does not model it, but there are situations where it wins and they are worth knowing.

The most common is student loans. Income-driven repayment plans can base the payment on the borrower's income alone when the couple files separately, and the reduction in payments can exceed the extra tax. Another is large medical expenses: the deduction only applies above 7.5% of AGI, so a spouse with heavy medical bills and a smaller income may clear the floor on a separate return when the couple could not clear it jointly. The third reason is not financial at all. A joint return makes both spouses liable for the whole tax bill, so anyone with doubts about a partner's reporting may prefer to keep their liability separate.

What this calculator does

Each spouse's column collects the income types that are taxed differently: salary and business income, interest and dividends, rental and other passive income, short-term gains taxed as ordinary income, and long-term gains and qualified dividends taxed at the preferential 0%, 15%, or 20% rates. Retirement contributions come out before tax. Then it applies the standard deduction, or your itemised figures if you turn that off, and the credits for dependents, child care, and tuition.

Payroll tax is calculated per person, which matters: Social Security tax stops at the wage base for each earner separately, so marriage never changes it. That is why the Social Security and Medicare rows are identical in both columns of the results table. The same is true of a flat state rate. Only the federal column moves, which is exactly the point.

The second chart sweeps spouse 2's income from zero upward while holding spouse 1 fixed, so you can see the whole shape at once: a large bonus when one spouse earns nothing, shrinking as incomes converge, and turning into a penalty only if both are high enough to reach the top brackets.

Timing and other practicalities

Because status is set on 31 December, the date of a wedding late in the year is a genuine tax decision. A couple heading for a bonus gains a full year of it by marrying in December rather than January. A couple heading for a penalty saves a year by doing the reverse. This is rarely the deciding factor in a wedding date, but it is free money to be aware of.

Marriage also changes withholding. Two people who each filled out a W-4 as single may be badly over- or under-withheld once they file jointly, since each employer only knows about its own paycheck. Redo the W-4 after marrying, particularly if both incomes are substantial, or the shortfall arrives as a bill and possibly an underpayment penalty. The Income Tax Calculator is the place to check the full-year figure.

One more thing this page cannot capture: health insurance. Combined income determines eligibility for premium tax credits on a marketplace plan, so marriage can reduce or remove a subsidy that one partner was receiving. For couples near the income limits, that effect can dwarf anything in the brackets.

Reading the result

Take the headline as a direction rather than a filing figure. It uses federal brackets, the standard deduction unless you override it, a flat state rate you supply, and a handful of the most common credits. Real returns bring in itemised deductions, state-specific rules, and credits this form does not collect.

The useful question is not whether the number is a penalty or a bonus, but how large it is next to everything else marriage changes: a spouse's health coverage, retirement contributions that become possible, estate treatment, and eventual Social Security. For most couples the annual tax difference is small, and it is the wrong thing to be optimising.