Getting married changes almost everything about your tax situation — sometimes for the better, sometimes not. Whether you experience a marriage tax bonus or penalty depends on how your incomes compare, which credits you qualify for, and how you choose to file. Here is how it works in 2025.
What Is the Marriage Tax Penalty?
A marriage tax penalty occurs when a married couple pays more in taxes filing jointly than they would have paid as two single filers. It happens because the married filing jointly (MFJ) brackets and deductions are not always double the single filer amounts.
In 2025, the standard deduction for MFJ is $31,500 — exactly double the $15,750 single deduction (both reflect OBBBA’s permanent $750 / $1,500 bump vs the TCJA baseline). And most MFJ tax brackets are double the single brackets. So for ordinary income, the penalty is minimal at most income levels.
However, the penalty kicks in at higher incomes. The 37% bracket begins at $626,350 for single filers but $751,600 for MFJ — well short of double. Two high earners making $500,000 each are pushed into the top bracket when they combine their income.
What Is the Marriage Tax Bonus?
A marriage tax bonus occurs when a couple pays less filing jointly than they would as two single filers. This is most common when one spouse earns significantly more than the other.
When one spouse earns $150,000 and the other earns $30,000, combining income on a joint return lets more of the higher earner’s income be taxed at lower rates. The wider MFJ brackets absorb the combined income more efficiently than the single brackets would for the higher earner alone.
When the Penalty Is Most Likely
The marriage penalty tends to affect:
- Dual high-income couples where both spouses earn roughly equal, substantial incomes
- Couples near the NIIT threshold ($250,000 MFJ vs. $200,000 single) — the net investment income tax threshold for MFJ is not double the single amount
- Couples near the SALT cap — under OBBBA (2025+) the SALT cap is $40,000 per return (MFJ) vs. $20,000 MFS, and phases down above $500,000 MAGI ($250,000 MFS). Two-earner households in high-tax states can still hit the cap faster than two single filers each claiming $40,000 if unmarried
- EITC eligibility — the income limits for the Earned Income Tax Credit can create penalties for some low-income couples
When the Bonus Is Most Likely
The marriage bonus favors:
- One-earner couples or couples with a large income disparity
- Couples where one spouse has losses (business losses, capital losses) that offset the other spouse’s income
- Couples who benefit from doubled deductions and credits on a joint return
Filing Jointly vs. Separately
Most married couples file jointly because it offers the lowest total tax. Filing separately (MFS) is rarely advantageous, but there are exceptions:
Reasons to consider filing separately:
- One spouse has large medical expenses (the 7.5% AGI threshold is lower with separate income)
- One spouse has student loans on an income-driven repayment plan (separate filing can lower the payment)
- You want to keep tax liability separate from a spouse’s potential issues (back taxes, audit risk)
- One spouse has significant miscellaneous deductions subject to AGI floors
Drawbacks of filing separately:
- You cannot claim the EITC, education credits, or the student loan interest deduction
- The Child Tax Credit is reduced or eliminated at lower income thresholds
- You must both itemize or both take the standard deduction — you cannot mix
- Roth IRA contribution limits phase out starting at $0 of MAGI (effectively eliminating Roth contributions)
Impact on Specific Credits and Deductions
| Item | Married Filing Jointly | Married Filing Separately |
|---|---|---|
| Standard Deduction | $31,500 | $15,750 |
| Child Tax Credit phase-out | Begins at $400,000 | Begins at $200,000 |
| EITC | Available | Not available |
| Student Loan Interest Deduction | Available (phase-out $165,000–$195,000) | Not available |
| Roth IRA Contribution | Phase-out $236,000–$246,000 | Phase-out $0–$10,000 |
Practical Example
Scenario 1: Marriage bonus. Alex earns $120,000 and Jordan earns $0. As a single filer, Alex pays approximately $19,360 in federal income tax. Filing jointly, the couple pays approximately $15,860 — a marriage bonus of about $3,500.
Scenario 2: Marriage penalty. Sam and Pat each earn $400,000. As two single filers, they would pay a combined $176,600 in federal income tax. Filing jointly with $800,000 combined income, they pay approximately $181,200 — a marriage penalty of about $4,600, largely driven by the compressed top bracket and NIIT.
Strategies to Minimize the Penalty
- Maximize retirement contributions. Each spouse contributing $23,500 to a 401(k) in 2025 reduces combined AGI by $47,000, potentially keeping you in lower brackets.
- Consider timing. If you are planning a December wedding and face a significant penalty, running the numbers for both years can inform your decision.
- Use HSAs and FSAs. These reduce taxable income dollar-for-dollar.
- Evaluate filing separately. Run your return both ways to see which produces the lower combined tax.
Bottom Line
The marriage tax penalty is real but affects mainly dual high-income couples. For most married couples — especially those with unequal incomes — filing jointly produces a tax bonus. Always run the numbers both ways (jointly and separately) to find the lowest total tax for your household. See IRS Publication 501 for detailed filing status rules.