What Is the Marriage Penalty and How to Avoid It?

The marriage penalty tax is the extra federal income tax a couple pays by filing a joint return compared to what the same two people would owe filing as unmarried individuals. It shows up most sharply for dual-earner couples with similar incomes, and it appears in more places than the tax brackets alone: capped deductions, phased-out credits, and Affordable Care Act surtaxes all treat married couples less favorably than two singles with the same combined income. For 2026, the clearest example sits at the top of the rate schedule, where the 37% bracket kicks in at $768,700 for joint filers rather than the $1,281,200 that true doubling of the $640,600 single threshold would produce.¹

How the Tax Brackets Create the Penalty

For 2026, the married-filing-jointly brackets are exactly double the single-filer brackets at every level except the top. The 10% bracket covers the first $24,800 of joint income (double the $12,400 for singles), the 12% bracket runs to $100,800 (double $50,400), and the pattern holds through the 35% bracket.¹ For most incomes, the bracket structure itself is neutral.

The compression happens at 37%. Two single filers could each earn up to $640,600 before crossing into the top rate, sheltering a combined $1,281,200 at lower rates. Married, they cross into 37% at $768,700, pushing $512,500 of combined income into the highest bracket that would otherwise have been taxed at 35% or less. For two professionals each earning around $500,000, this bracket compression produces a measurable tax increase tied to nothing but their filing status. The One Big Beautiful Bill Act made the seven current rates permanent, so this top-bracket structure is not a temporary quirk.¹

The Head of Household Deduction You Lose by Marrying

The 2026 standard deduction is $16,100 for single filers and $32,200 for joint filers, a clean doubling.¹ The hidden penalty is a filing status marriage takes off the table.

An unmarried person supporting dependents can file as Head of Household, which carries a $24,150 standard deduction for 2026.¹ Two unmarried partners living together, one filing as Head of Household and the other as single, combine for $40,250 in standard deductions. After marriage, they get $32,200. That’s $8,050 of income newly exposed to tax before any rate applies. Households where one partner previously qualified for Head of Household status often feel this first.

The SALT Cap Doesn’t Double

The state and local tax deduction lets you subtract property taxes, state income taxes, and local taxes from federal taxable income, subject to a cap. For 2026, that cap is $40,400 for single filers and $40,400 for married couples filing jointly, the same number for both.² Two unmarried people sharing a home could each deduct up to $40,400, for a combined $80,800. Married, the household is limited to $40,400 total.

The cap also phases down for higher earners. When modified AGI exceeds $505,000, the $40,400 limit shrinks by 30% of the income above that threshold, bottoming out at $10,000.² Because the phasedown threshold does not appear to double for joint filers, high-earning couples in high-tax states face a compounding effect: a lower starting cap and a faster reduction of it. Married filing separately gets half the cap, $20,200, so that route does not restore the lost deduction.

Earned Income Tax Credit Phase-Outs

The EITC is one of the largest cash benefits in the code for lower- and moderate-income workers, and the income limits for married couples are only modestly higher than for singles, not double. For 2026, a single parent with two qualifying children can claim the EITC with earned income up to $58,629. A married couple with the same two children loses the credit entirely once combined income tops $65,899.³

If both partners were single, their theoretical combined ceiling would be $117,258. Marriage cuts that to $65,899. In practice, a second earner bringing home $25,000 or $30,000 can disqualify the household from a credit worth thousands. Families weighing childcare costs against a second income can find that working more hours actually reduces after-tax household resources.

Medicare Surtax and Net Investment Income Tax

Two Affordable Care Act surtaxes carry their own penalties, and unlike the regular brackets, their thresholds have never been adjusted for inflation. The 0.9% Additional Medicare Tax applies to wages and self-employment income above $200,000 for single filers and $250,000 for joint filers.⁴ The 3.8% Net Investment Income Tax hits net investment income when modified AGI exceeds the same $200,000 single and $250,000 joint thresholds.⁵ True doubling would put the joint threshold at $400,000.

Two unmarried partners each earning $190,000 would owe neither surtax. Married with $380,000 combined, they’re $130,000 over the joint threshold and pay the Medicare surtax on the wage overage and the NIIT on any investment income above it. Because the thresholds are frozen at their original 2013 levels, inflation drags more couples into the penalty zone each year.⁵

Who Actually Gets Penalized

Whether marriage raises or lowers a federal tax bill depends mostly on how income is split between the spouses. Two partners earning roughly the same amount are the most likely to be penalized. When two $150,000 incomes combine into a $300,000 joint return, that combined figure pushes into bracket ranges, deduction caps, and credit phase-outs that neither person hit individually. Every mechanism above bites harder when earnings are balanced.

The reverse produces a marriage bonus. When one spouse earns most or all of the household income and the other earns little, the high earner’s income spreads across the wider joint brackets, pulling dollars that would have been taxed at 24% or 32% down into 12% or 22%. The couple pays less together than the working spouse would have paid alone. One analysis found a single-earner couple with $200,000 in income and two children could see a marriage bonus of roughly 3% of income, while a dual-earner couple with the same total and children faced a penalty of about 1.6%.⁶

So the penalty is not a universal feature of marriage. It targets a specific profile: two working adults with comparable incomes, especially in the upper-middle and high-income ranges. Single-earner households and couples with wide income gaps are far more likely to come out ahead.

Does Filing Separately Help?

Married Filing Separately is the first workaround couples consider, and for most it backfires. The separate-filer brackets mirror the single-filer brackets, and the standard deduction is $16,100, exactly half the joint amount, so separate filing does not recreate single-filer math on its own.¹ It also closes off major benefits.

Couples filing separately cannot claim the EITC at all and generally cannot take the child and dependent care credit.⁷ Education credits like the American Opportunity Credit and Lifetime Learning Credit are unavailable, the student loan interest deduction disappears, and the SALT cap drops to $20,200. For most couples, the credits and deductions given up cost more than any penalty they are trying to avoid.

Separate filing can still make sense in narrow situations. If one spouse has large unreimbursed medical expenses or other deductions subject to AGI-based floors, a lower individual AGI on a separate return can make more of those expenses deductible. The same logic applies when one spouse carries significant student loan debt and uses an income-driven repayment plan, where a lower reported AGI keeps monthly payments down. These are case-by-case calculations. Running the numbers both ways before filing is the only reliable way to tell which approach saves money.

State Taxes Can Stack on Top

The federal penalty gets the most attention, but roughly a third of states with income taxes have their own version, either through married brackets set at less than double the single brackets or through caps and credits that mirror the federal structure. In some states, the added state-level penalty on a dual-earner couple can reach several thousand dollars a year. Couples in high-tax states can see federal and state penalties compound; couples in states without an income tax avoid this layer entirely.

1
Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
2
Office of the Law Revision Counsel. 26 USC 164 – Taxes
3
Internal Revenue Service. Earned Income and Earned Income Tax Credit (EITC) Tables
4
Internal Revenue Service. Questions and Answers for the Additional Medicare Tax
5
Internal Revenue Service. Questions and Answers on the Net Investment Income Tax
6
Tax Policy Center. What Are Marriage Penalties and Bonuses
7
Taxpayer Advocate Service. The Tax Ramifications of Tying the Knot