Getting married changes almost every number on your federal tax return. For 2026, a married couple filing jointly gets a $32,200 standard deduction, while a single filer gets $16,100.1Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 The married vs. single taxes comparison usually favors the married couple, especially when one spouse earns much more than the other, but two high earners with similar incomes can pay a penalty, and the third option — married filing separately — is almost always worse than filing single would be if you weren’t married at all.
Your status is fixed by your situation on December 31. Marry on New Year’s Eve and the IRS treats you as married for the whole year. Finalize a divorce on December 30 and you file as single. No proration.2Internal Revenue Service. Filing Status
Standard Deduction: Married vs. Single
The standard deduction comes off your income before tax rates apply. For 2026:1Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
- Married Filing Jointly: $32,200
- Head of Household: $24,150
- Single: $16,100
- Married Filing Separately: $16,100
Joint filers get exactly double the single amount. Married Filing Separately (MFS) matches single, so filing separately gives no deduction advantage over filing single, and it comes with a catch: if one spouse itemizes on a separate return, the other spouse must itemize too, even if their itemized total falls short of $16,100.3Internal Revenue Service. Other Deduction Questions
How the Tax Brackets Compare
Federal tax rates rise in slices, and your filing status decides where each rate kicks in. For 2026:1Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
- 10%: Single up to $12,400; MFJ up to $24,800
- 12%: Single $12,401–$50,400; MFJ $24,801–$100,800
- 22%: Single $50,401–$105,700; MFJ $100,801–$211,400
- 24%: Single $105,701–$201,775; MFJ $211,401–$403,550
- 32%: Single $201,776–$256,225; MFJ $403,551–$512,450
- 35%: Single $256,226–$640,600; MFJ $512,451–$768,700
- 37%: Single over $640,600; MFJ over $768,700
Through the 32% bracket, joint thresholds are exactly twice the single thresholds. At 35% and 37% they aren’t. A joint return hits 35% at $512,450; two single filers wouldn’t reach 35% until each had $256,226 in taxable income, which is a combined $512,452. The gap widens at 37%. This is the marriage penalty, and it lives at the top of the brackets, where two high, roughly equal earners lose space they’d have kept as singles.
When incomes are uneven, marriage does the opposite. A spouse earning little or nothing fills the bottom of the joint brackets that a solo high earner never uses. A couple where one person earns $200,000 and the other earns $30,000 pays noticeably less on a joint return than the sum of two hypothetical single returns. The bigger the income gap, the bigger the marriage bonus.
Filing separately doesn’t rescue two equal earners from the penalty. The MFS brackets match single only up through 32%; MFS hits the 37% rate at roughly $384,350, while a single filer doesn’t reach it until $640,600.
What Married Filing Separately Costs You
If you’re weighing married-vs-single as a married person, the real question is usually joint vs. separate. Separate returns look appealing when spouses want independence, but the tax code punishes MFS across the board. Many of these benefits are simply gone, or cut in half, once you check that box.
Earned Income Tax Credit
Generally unavailable to MFS filers. The only escape is a narrow one: living apart from your spouse for the last six months of the year, or being legally separated.4Internal Revenue Service. Who Qualifies for the Earned Income Tax Credit (EITC)
Education Credits
Neither the American Opportunity Credit (worth up to $2,500 per student) nor the Lifetime Learning Credit can be claimed on an MFS return.5Internal Revenue Service. Education Credits: AOTC and LLC
Child and Dependent Care Credit
Generally unavailable to MFS filers, with a limited exception for spouses who lived apart.6Internal Revenue Service. Topic No. 602, Child and Dependent Care Credit
Student Loan Interest
The $2,500 student loan interest deduction is off the table for MFS filers. No exceptions.7Internal Revenue Service. Topic No. 456, Student Loan Interest Deduction
Adoption Credit
Married taxpayers generally must file jointly to claim it. MFS is allowed only if the spouses lived apart for the last six months of the year and meet additional requirements.8Internal Revenue Service. Instructions for Form 8839 (2025)
Roth IRA Contributions
For 2026, a single filer can make full Roth contributions with MAGI below $153,000, phasing out at $168,000. Joint filers get $242,000 to $252,000. MFS filers who lived with their spouse at any point during the year get a phase-out from $0 to $10,000, which effectively zeroes out contributions for anyone with real earnings.9Internal Revenue Service. Amount of Roth IRA Contributions That You Can Make for 2024
Child Tax Credit
MFS filers can claim it, but the phase-out begins at $200,000 rather than the $400,000 joint threshold.10Internal Revenue Service. Child Tax Credit
Surtaxes and Limits That Shift by Status
Beyond credits, several thresholds move with filing status. They quietly add up.
Net Investment Income Tax. A 3.8% surtax on investment income begins at $250,000 MAGI for joint filers, $200,000 for single, and $125,000 for MFS. These thresholds are not inflation-adjusted.11Internal Revenue Service. Topic No. 559, Net Investment Income Tax
Additional Medicare Tax. A 0.9% surtax on wages and self-employment income above $250,000 (MFJ), $200,000 (single), $125,000 (MFS). Also not inflation-adjusted.12Internal Revenue Service. Questions and Answers for the Additional Medicare Tax
Social Security benefits. Up to 50% become taxable when combined income tops $25,000 for singles and $32,000 for joint filers; up to 85% at $34,000 and $44,000 respectively. MFS filers who lived with their spouse at any point in the year get the harshest rule: up to 85% of benefits taxable with no income floor at all.13Internal Revenue Service. IRS Reminds Taxpayers Their Social Security Benefits May Be Taxable
Capital loss deduction. Net capital losses against ordinary income are capped at $3,000 — $1,500 for MFS.14Internal Revenue Service. Topic No. 409, Capital Gains and Losses
State and local tax deduction. The 2026 SALT cap is $40,400, halved to $20,200 for MFS. The cap phases down above $500,000 MAGI for joint filers and $250,000 for MFS.15Internal Revenue Service. How to Update Withholding to Account for Tax Law Changes for 2025
Alternative Minimum Tax. The 2026 AMT exemption is $140,200 for joint filers, $90,100 for single, and $70,100 for MFS. Joint filers keep the full exemption until $1,000,000 in income; the single phase-out starts at $500,000.1Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
Marriage Bonus vs. Marriage Penalty in Practice
Put the pieces together and a pattern emerges. If one of you earns significantly more than the other, marriage cuts your combined tax through wider joint brackets and a doubled standard deduction. If both of you earn high, similar incomes, you may end up paying more jointly than you would have as two single filers, because the top brackets aren’t fully doubled and several surtax thresholds aren’t doubled either. Filing separately doesn’t fix that; it costs you credits, halves your capital loss and SALT limits, kills your Roth eligibility in most cases, and pushes surtaxes onto lower income.
When Filing Separately Is Still the Right Move
MFS earns its keep in a handful of situations.
Shielding Yourself from Your Spouse’s Tax Exposure
A joint return creates joint and several liability: the IRS can collect the full bill, plus penalties and interest, from either spouse, even for income only one of you earned.16eCFR. 26 CFR 1.6015-1 If your spouse has unreported income, aggressive positions, or old tax debt, MFS keeps your return your own. This matters most during marital strain or the runup to a divorce.
Unlocking the Medical Expense Deduction
Medical expenses are deductible only above 7.5% of AGI.17Internal Revenue Service. Publication 502 (2025), Medical and Dental Expenses If one spouse has heavy medical bills and modest personal income, isolating that spouse’s AGI on a separate return can clear the floor when a joint AGI wouldn’t. A spouse earning $40,000 with $10,000 in medical costs deducts $7,000 on a separate return; on a joint return with $150,000 combined AGI, the floor rises to $11,250 and the deduction vanishes. Run the credits you’d lose against the deduction you’d gain before deciding.
Community Property States
Nine states treat income earned during marriage as owned equally by both spouses. On separate returns, each spouse reports half the community income and half the community deductions, which often erases the AGI-splitting benefit above.18Internal Revenue Service. Publication 555 (12/2024), Community Property
Income-Driven Student Loan Payments
Some federal income-driven repayment plans base payments on the borrower’s own income rather than household income. Filing MFS keeps a lower-earning spouse’s payment down. Whether the savings beat the tax cost depends on the loan balance, rate, and which credits you’d forfeit.
If You’re Married but Living Apart
Being married doesn’t lock you into MFJ or MFS. If you lived apart from your spouse for the last six months of the year, paid more than half the cost of keeping up a home, and had a dependent child living with you for more than half the year, you can file as Head of Household even while legally married.19Internal Revenue Service. Publication 504 (2025), Divorced or Separated Individuals Head of Household comes with a $24,150 standard deduction for 2026 and wider brackets than single or MFS, making it far better than filing separately for separated parents who qualify.1Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
Running Your Own Comparison
For most married couples, a joint return produces the lowest bill. The standard deduction is bigger, the brackets are wider, and every credit stays on the table. The marriage bonus for uneven earners often runs into the thousands, and even for equal earners, the penalty at the top brackets is usually smaller than the credits and deductions MFS would forfeit.
If you’re a married person genuinely comparing your options, calculate the tax both ways, joint and separate, with every lost credit priced in. One planning quirk to keep in mind: the IRS lets you amend from MFS to MFJ within three years, but you cannot switch from MFJ to MFS after the filing deadline. Choose carefully the first time.