In taxes, MAGI stands for modified adjusted gross income, and it’s the income figure the IRS uses to decide whether you qualify for certain credits, deductions, retirement account contributions, and premium subsidies. You calculate it by starting with your adjusted gross income and adding back specific deductions or exclusions you already claimed. The wrinkle is that MAGI doesn’t have one fixed definition: the items you add back depend on which tax benefit you’re testing eligibility for.
MAGI vs. AGI
Your adjusted gross income is the number on line 11 of Form 1040. It’s your total income from wages, investments, business, and other sources, minus a set of above-the-line deductions like health savings account contributions, self-employment tax, and retirement plan contributions listed on Schedule 1.1Internal Revenue Service. Modified Adjusted Gross Income For most tax purposes, AGI is your starting point.
MAGI takes that AGI number and adds certain items back. The idea is straightforward: Congress wanted to prevent people from using specific deductions or exclusions to shrink their income and slip under eligibility thresholds. Adding those items back gives a fuller picture of your actual economic resources.
You won’t find a line labeled “MAGI” on your tax return. Instead, you calculate it using the worksheet or instructions for the specific credit or deduction you’re claiming. This is where people trip up. They assume there’s one universal MAGI figure when there are actually several, each governed by different rules.
How to Calculate MAGI
The basic formula is always the same: start with AGI and add back specific items. What varies is which items get added back. The IRS lists these as the most common add-backs across tax provisions:1Internal Revenue Service. Modified Adjusted Gross Income
- Foreign earned income and the housing exclusion under Section 911.
- The student loan interest deduction from Schedule 1, line 21.
- The traditional IRA deduction from Schedule 1, line 20.
- Tax-exempt interest from municipal bonds and similar sources, reported on Form 1040, line 2a.
- Employer-provided adoption assistance you excluded from income.
- Interest from U.S. savings bonds used for education that you excluded.
- Nontaxable Social Security benefits.
No single calculation uses all of these. Roth IRA MAGI adds back foreign earned income and the student loan interest deduction. Medicare’s premium surcharge uses AGI plus tax-exempt interest and nothing else.2Social Security Administration. Modified Adjusted Gross Income (MAGI) The Premium Tax Credit for marketplace health insurance pulls in AGI plus foreign earned income, tax-exempt interest, and nontaxable Social Security benefits. The rental real estate loss allowance uses its own list, defined by statute, that excludes passive losses, IRA deductions, taxable Social Security, and the savings bond exclusion, among others.3Office of the Law Revision Counsel. 26 USC 469 – Passive Activity Losses and Credits Limited
Always check the worksheet for the specific benefit you’re claiming rather than assuming one MAGI fits every purpose.
Why There Isn’t One MAGI
Each tax provision that uses MAGI defines it in its own statute. Congress writes each rule to close a specific gap, so the add-backs are tailored to what that particular benefit is trying to measure. If a credit is meant to help lower-income families with health insurance, it makes sense to add back untaxed Social Security and foreign income, because those are real resources the family has. If a rule is limiting rental loss deductions for higher earners, the definition strips out items that would otherwise let a landlord look poorer than they are.
The practical result is that you can technically have several MAGI figures on the same return. Your Roth IRA MAGI, your student loan interest MAGI, your Medicare IRMAA MAGI, and your Premium Tax Credit MAGI can all be different numbers, even though they start from the same AGI.
Where MAGI Actually Affects Your Return
MAGI shows up as a gatekeeper for a long list of tax benefits. A quick tour of the main ones tells you where to look on your own return.
Retirement Contributions
Roth IRA eligibility phases out as MAGI rises. For 2026, single filers get full contributions below $153,000 MAGI, a reduced amount between $153,000 and $168,000, and nothing above $168,000. Married couples filing jointly phase out between $242,000 and $252,000.4Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500 The statute reduces your allowable contribution proportionally as income moves through the phase-out range.5Office of the Law Revision Counsel. 26 USC 408A – Roth IRAs
Traditional IRA contributions are always allowed, but MAGI controls whether you can deduct them when you or your spouse is covered by a workplace retirement plan. If neither of you has workplace coverage, MAGI doesn’t limit the deduction at all.
Student Loan Interest
You can deduct up to $2,500 in student loan interest per year, but the deduction shrinks and disappears as MAGI climbs. For 2026, single filers phase out between $85,000 and $100,000, and joint filers between $175,000 and $205,000. Married filing separately gets no deduction at any income.6Internal Revenue Service. Rev. Proc. 2025-32
Education Credits
The American Opportunity Tax Credit and the Lifetime Learning Credit share a phase-out structure for 2026: the credit shrinks starting at $80,000 MAGI for single filers and $160,000 for joint filers, and disappears at $90,000 and $180,000.7Internal Revenue Service. Education Credits: American Opportunity Tax Credit (AOTC) and Lifetime Learning Credit (LLC)
Premium Tax Credit
If you buy health coverage through the ACA marketplace, MAGI decides whether you qualify for a subsidy. For 2026, the temporarily expanded subsidies have expired, and the 400% federal poverty level ceiling is back in force, so household MAGI above that level generally disqualifies you from any credit.8Congress.gov. Enhanced Premium Tax Credit and 2026 Exchange Premiums If you got advance credit payments during the year and your actual MAGI comes in higher than estimated, you’ll repay some or all of the excess when you file.9Office of the Law Revision Counsel. 26 US Code 36B – Refundable Credit for Coverage Under a Qualified Health Plan
Child Tax Credit
For 2026, the child tax credit is worth up to $2,200 per qualifying child under age 17. The credit starts to phase out at $200,000 MAGI for single and head-of-household filers and $400,000 for married couples filing jointly, dropping by $50 for every $1,000 of income over the threshold.10Congress.gov. The Child Tax Credit: How It Works and Who Receives It
Net Investment Income Tax
Higher earners face a 3.8% surtax on investment income when MAGI exceeds $200,000 single, $250,000 joint, or $125,000 married filing separately. These thresholds are written into statute and don’t adjust for inflation, so more taxpayers cross them each year.11Office of the Law Revision Counsel. 26 USC 1411 – Imposition of Tax The tax applies to the smaller of your net investment income or the amount by which MAGI exceeds the threshold. People who sell a home, exercise stock options, or realize large capital gains in a single year are often surprised by it.
Medicare Premiums
MAGI also reaches beyond your tax return. Social Security uses MAGI from the return you filed two years earlier to set your Medicare Part B and Part D premium surcharges, known as IRMAA. For Medicare purposes, MAGI is AGI plus tax-exempt interest.2Social Security Administration. Modified Adjusted Gross Income (MAGI) The standard 2026 Part B premium is $202.90 per month, with surcharges kicking in above $109,000 single and $218,000 joint, and rising through five tiers.12Centers for Medicare & Medicaid Services. 2026 Medicare Parts A & B Premiums and Deductibles If your income dropped significantly because of retirement, a spouse’s death, divorce, or a similar life change, you can request a reduction with Form SSA-44.
What Happens If You Get MAGI Wrong
Miscalculating MAGI can cost more than the extra tax alone. If you claim a credit or deduction you weren’t entitled to because your income was actually too high, the IRS can assess an accuracy-related penalty of 20% on the underpayment. That penalty applies whenever the understatement exceeds the greater of 10% of the tax you should have owed or $5,000.13Internal Revenue Service. Accuracy-Related Penalty
For the Premium Tax Credit, the mechanics are more immediate. If you received advance subsidy payments during the year and your actual MAGI is higher than what you estimated, you owe the difference back when you file. In some cases the entire advance amount must be repaid.
Errors run the other direction too. Overestimating your MAGI can push you to skip benefits you actually qualify for. Nobody at the IRS will call to tell you that you could have contributed to a Roth IRA or claimed an education credit. These are self-reported, so getting the calculation right is on you. When your income sits near any of the phase-out ranges above, working through the specific worksheet for each benefit is worth the time.