Marriage Penalty Guide

What Is the Marriage Penalty?

The federal income tax is figured on a household's return, not on each person. Once you are married you can file only as married filing jointly or married filing separately, and each status has its own brackets, standard deduction and thresholds. The marriage penalty is the amount by which your married tax is higher than the total the two of you would pay on two unmarried returns (single, or head of household if you qualify). When the married tax is lower, the difference is a marriage bonus.

The comparison is hypothetical: once you are married you cannot choose to file as single. It is still worth running before a wedding, when buying a home, or when one partner's income changes, because it explains a tax bill that went up or down for reasons that have nothing to do with your raise or your deductions.

Where Do Single and Joint Brackets Stop Being Equal?

The rate schedules in IRC 1(j) are adjusted for inflation every year. For 2025 (Rev. Proc. 2024-40) and 2026 (Rev. Proc. 2025-32) every married filing jointly threshold through the top of the 32% bracket is exactly twice the single threshold, and the joint standard deduction is twice the single one. Only the 35% bracket is narrower for couples, so the 37% rate starts well below twice the single starting point.

The practical result: if your joint taxable income stays within the 32% bracket, the brackets themselves cannot create a penalty, however your income is split. Two people each earning enough to reach the 35% bracket on their own are where the bracket penalty remains. In 2026, two partners who each have $500,000 of wages pay $3,982 more income tax on a joint return than as single filers, before counting the Medicare surtax.

Who Gets a Marriage Bonus?

Couples with uneven incomes. On a joint return the higher earner's income fills the 10% and 12% brackets and the standard deduction that the lower earner would not have used on their own return. The bigger the gap, the bigger the bonus, and a one-earner couple gets the most.

• $150,000 and $0 (2026): $24,734 single vs $15,340 joint, a $9,394 bonus.
• $150,000 and $40,000 (2026): $27,354 as two singles vs $24,140 joint, a $3,214 bonus.
• $100,000 and $100,000 (2026): $26,340 either way, no penalty and no bonus.

The same logic is why many retirees, single-income households and couples where one partner is in school or between jobs see their tax fall after marriage.

How Does the SALT Limit Penalize Married Couples?

The deduction for state and local income, sales and property taxes is limited by IRC 164(b)(6) and (7). The "applicable limitation amount" is $40,000 for 2025 and $40,400 for 2026, rising 1% a year through 2029 and returning to $10,000 for 2030. It is reduced by 30% of modified adjusted gross income over $500,000 (2025) or $505,000 (2026), but not below $10,000. Married filing separately gets half of the limit and half of the threshold.

The statute uses the same limit for a single return and a joint return. Two unmarried homeowners who each pay $30,000 of state income and property tax can each deduct all of it. Married, they deduct only $40,400 between them in 2026, losing $19,600 of deductions. At a 24% rate that is a $4,704 marriage penalty from the SALT limit alone. The threshold for the phase-down is also not doubled, so a couple whose combined income passes $505,000 starts losing the deduction even if neither partner would have on their own.

What Happens to Head of Household Status When You Marry?

Head of household is for people who are unmarried (or considered unmarried) on the last day of the year, paid more than half the cost of keeping up a home, and had a qualifying person living with them for more than half the year, according to IRS Publication 501. It comes with wider brackets than single (the 12% bracket runs to $67,450 for 2026 against $50,400 single) and a larger standard deduction ($24,150 for 2026 against $16,100).

Marriage ends it. A single parent earning $60,000 as head of household who marries someone earning $60,000 goes from $3,948 + $5,020 = $8,968 of 2026 income tax on two returns to $10,040 on a joint return, a $1,072 penalty before credits. Couples with children should also check how the joint return changes the earned income credit and other credits, which this example leaves out.

Which Other Thresholds Are Not Doubled for Couples?

Several amounts in the tax code are fixed in the statute and give a joint return less than twice the single amount:

• Additional Medicare Tax (0.9%): applies to wages and self-employment income over $250,000 on a joint return, $125,000 married filing separately and $200,000 for everyone else (IRS Topic 560). Two partners each earning $200,000 owe none as singles but $1,350 married.
• Net investment income tax (3.8%): the IRC 1411(b) threshold is $250,000 for a joint return, half that for married filing separately and $200,000 in any other case.
• Capital loss limit: IRC 1211(b) lets net capital losses offset up to $3,000 of other income a year, $1,500 if married filing separately. A couple gets one $3,000 limit, not two.
• Credits with phase-outs: some credits use joint income limits that are less than double the single ones, which is where lower-income couples can see the largest penalties. The child tax credit is an exception: its phase-out begins at $200,000 of income for most filers and $400,000 for joint filers, as Form W-4 Step 3 shows.

These thresholds are not indexed for inflation, so more couples reach them each year.

Does the Date You Get Married Matter?

Yes. IRS Publication 501 says you are considered married for the whole year if, on the last day of your tax year, you are married (including living apart but not legally separated under a decree). Marrying on December 31 makes you married for all of that year; marrying on January 1 lets each of you file as unmarried for the year that just ended.

If the comparison shows a penalty, a January wedding delays it by a year. If it shows a bonus, a December wedding claims it a year sooner. The same rule works in reverse for divorce: a final decree by December 31 means you file as unmarried for that whole year.

Can Filing Separately Avoid the Penalty?

Rarely. Married filing separately uses the single brackets through the 32% bracket, but its 35% bracket is short and the 37% rate starts at half the joint threshold ($384,350 for 2026, against $640,600 single), the SALT limit and capital loss limit are halved, and many benefits are reduced or not allowed on separate returns, including the earned income credit and the education credits in most cases. If one spouse itemizes on a separate return, the other must too. For most couples the joint return is cheaper.

Separate returns can still make sense for reasons other than tax rates: keeping liability for a spouse's return separate, or an income-driven student loan payment that is based on the return. Compare both options with the Filing Status Calculator.

How Do You Fix Withholding After Marriage?

Most newly married couples who owe at tax time do not have a marriage penalty. They have a withholding gap: each employer withholds as though its job were the only income, so both paychecks start with a full standard deduction and the low brackets that the joint return can only use once. Form W-4 Step 2 is built for this. You can use the IRS Tax Withholding Estimator, use the Multiple Jobs Worksheet, or, if there are only two jobs in total, check the box in Step 2(c) on both partners' forms. The form says Step 2(c) is generally more accurate when the lower-paying job pays more than half of the higher-paying one.

Submit new Forms W-4 soon after the wedding, and see the How to Fill Out a W-4 guide or the W-4 Withholding Calculator for the details.

Practitioner Insight (LMN Tax Inc.)

Real-World Scenarios

When the Rules Differ

• Earned income credit and other credits. Joint income limits for many credits are less than double the single limits, so couples who each claimed a credit can lose much of it. Run the EITC Calculator on the joint income.
• Capital gains and qualified dividends. The 0%, 15% and 20% rates have their own single and joint breakpoints.
• Schedule 1-A deductions (2025 to 2028). The deductions for tips, overtime, car loan interest and seniors have their own limits and phase-outs by filing status; check each one on the joint return.
• Surviving spouses. A qualifying surviving spouse uses the joint brackets and standard deduction for up to two years after the year of death if the requirements in Publication 501 are met.
• Nonresident spouses. A joint return with a nonresident alien spouse requires an election to treat the spouse as a U.S. resident; otherwise the U.S. spouse files as married filing separately or, in some cases, head of household.
• State taxes. Many states have their own marriage penalty or bonus, and some let married couples file separately on the state return even when they file jointly for federal purposes.

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