Marriage Tax Calculator —
penalty or bonus?

Field guide

The marriage tax penalty and bonus, explained.

When two people marry in the United States, their combined federal income tax liability may go up, go down, or stay the same, depending entirely on how much each partner earns. The IRS does not have a single “married” rate; instead, the tax code applies different bracket widths and a different standard deduction for married couples filing jointly (MFJ) versus single filers. The arithmetic sometimes favors married couples and sometimes penalizes them.

The marriage penalty

A marriage tax penalty occurs when a couple's combined federal tax as a married unit exceeds the sum of what each would pay as single filers. It arises because the upper tax brackets, particularly 35% and 37%, are not exactly twice as wide for married couples as they are for singles.

In 2026, the critical thresholds are:

The 10% through 32% brackets are exactly doubled for MFJ; no penalty there. But the 35% bracket for a married couple is only $261,050 wide ($521K–$782K), while two singles each get a 35% bracket that is $391,150 wide. Two high-income singles can shelter more income in the 35% bracket than one married couple can.

The marriage bonus

A marriage bonus occurs when the joint return produces a lower combined tax than two single returns. This most commonly happens when one partner earns significantly more than the other. The lower-income spouse's income “absorbs” into the lower end of the wider MFJ brackets, while the combined income still stays within bracket ranges that are exactly double the single equivalents.

Classic bonus example: one partner earns $120,000 (in the 22% bracket as single), the other earns $60,000 (12% bracket as single). Combined MFJ income of $180,000 still falls in the 22% bracket for married couples. The $32,200 joint standard deduction (vs $16,100 + $16,100 = $32,200) is identical, but the lower-income spouse avoids being taxed at the 22% rate on their own return. Instead, their income blends favorably into the MFJ bracket structure.

Who is affected, and by how much?

Research by the Tax Policy Center and Tax Foundation shows that:

• Most married couples receive a bonus: roughly two-thirds, primarily those with disparate incomes or a stay-at-home spouse. These couples benefit from the doubled standard deduction and the effective income-splitting the joint return provides.
• Dual high-earners face the largest penalties — two partners each earning $350,000–$800,000 can face marriage penalties of $10,000–$25,000 per year, almost entirely from the compressed 35% and 37% bracket widths.
• Low-income couples can face significant EITC penalties (not modeled here), where combined income disqualifies the couple from credits each partner qualified for individually.

Can filing separately avoid the penalty?

Generally, no. Married Filing Separately (MFS) uses the exact same bracket widths as the single brackets — it does not give you “two separate” returns. In addition, MFS filers lose access to several valuable deductions and credits: student loan interest deduction, IRA deduction (if either spouse is covered by a workplace plan), the EITC, child and dependent care credit, and American Opportunity Credit. For most couples, MFS produces higher total taxes than MFJ despite the penalty.

There are narrow exceptions, primarily when one spouse has large medical expenses (deductible above 7.5% of AGI, and a lower individual AGI makes more expenses deductible), or in legal separation/divorce proceedings. Tax professionals advise running both returns and comparing.

The standard deduction and the penalty

The 2026 standard deduction is $16,100 for single filers and $32,200 for MFJ, exactly double. This part of the tax code is marriage-neutral: a couple claiming the standard deduction neither gains nor loses from this provision. The penalty arises entirely from the narrower upper-bracket widths, not from the standard deduction. Itemizing deductions can change the math significantly — a couple who itemizes jointly may get a larger combined deduction than two single itemizers, or vice versa.

Other tax changes at marriage

This calculator only models federal income tax. Marriage also triggers other tax changes not captured here:

• Social Security benefit taxation: combined income thresholds for taxing SS benefits are $44,000 (MFJ) vs $34,000 (single), meaning married couples face benefit taxation at lower relative income levels.
• Medicare surtax: the 3.8% Net Investment Income Tax and the 0.9% Additional Medicare Tax both have lower MFJ thresholds ($250,000) relative to double the single threshold ($400,000 × 2 = $800,000), creating penalties for investment- heavy couples.
• Capital gains rates: the 0% long-term capital gains bracket ends at $94,050 for singles and $188,100 for MFJ (2026), exactly double, so no penalty here.
• Estate tax: the unlimited marital deduction allows a spouse to inherit the entire estate tax-free. Married couples also benefit from portability of the unused estate tax exemption.