How to Find Your MAGI: Step-by-Step Calculation and Add-Backs

To calculate your MAGI, start with the adjusted gross income on Line 11a of your Form 1040 and add back certain items the IRS excluded or let you deduct — most commonly tax-exempt interest, nontaxable Social Security benefits, foreign earned income exclusions, the student loan interest deduction, and employer-provided adoption benefits.¹ The catch is that there is no single MAGI. Each tax provision that uses MAGI defines its own version, so which items you add back depends on what you’re calculating it for.

Start With Your AGI

Every version of MAGI begins with AGI, which is your total income minus above-the-line deductions such as retirement plan contributions, health savings account contributions, and the deductible portion of self-employment tax.² On the 2025 Form 1040 (filed in 2026), AGI is on Line 11a.³ If you’ve already filed, you can pull it from last year’s return or request a transcript from the IRS.

Not filed yet? Estimate it. Add up wages, investment income, rental income, and retirement distributions, then subtract the above-the-line deductions you expect to claim. That estimate is the foundation for projecting MAGI during the year, which matters if you’re timing IRA contributions or gauging ACA subsidy eligibility.

One reassuring point before the add-backs: if you earn all your income domestically, have no tax-exempt interest, and receive no Social Security, your MAGI and AGI are often the same number.¹ The formulas only diverge when one of those factors is in play, or you claimed a deduction the formula tells you to add back.

The General Calculation, Step by Step

The most widely used MAGI formula is the one for the Premium Tax Credit under the Affordable Care Act. It captures nearly all forms of income and works like this:⁴

Start with AGI on Line 11a of Form 1040.
Add tax-exempt interest from Line 2a. This is interest from municipal bonds and similar investments that isn’t in taxable income but still counts toward MAGI.³
Add the nontaxable portion of Social Security benefits. Subtract Line 6b (taxable amount) from Line 6a (total benefits); the difference is the amount you add back.³
Add foreign earned income exclusions. If you filed Form 2555 to exclude income earned abroad, add back the exclusion from Line 45 (and the housing deduction from Line 50, if you used it).⁵

That total is your ACA MAGI. For other tax benefits, the starting point is the same, but the add-backs (and occasional subtractions) change.

How the Add-Backs Change by Tax Benefit

Below are the differences you’re most likely to run into. Each version is still called “MAGI,” and the number will not always match.

Roth IRA Contributions

For Roth eligibility, you start with AGI and add back the student loan interest deduction (Schedule 1, Line 21), the foreign earned income and housing exclusions, and the exclusion for employer-provided adoption benefits.¹ You then subtract income from Roth IRA conversions and rollovers — an unusual step that keeps conversion income from pushing you over the contribution limit. Worksheet 2-1 in IRS Publication 590-A walks through the math, with your final MAGI on Line 10.⁶

The Traditional IRA deduction uses a similar calculation, but it only matters if you or your spouse is covered by a workplace retirement plan. If neither of you is covered, the deduction is available regardless of income.⁷

Education Credits and Student Loan Interest

The American Opportunity Tax Credit, the Lifetime Learning Credit, and the student loan interest deduction all use a MAGI that starts with AGI and adds back foreign earned income exclusions, the foreign housing deduction, and excluded income from U.S. territories.¹ For the student loan interest deduction, you do not add the deduction itself back, because the whole point is to determine whether you qualify for it.

Coverdell Education Savings Accounts use a different set of add-backs: AGI plus the student loan interest deduction and employer-provided adoption benefits excluded from income.¹ Your Coverdell MAGI will usually run higher than your student-loan-interest MAGI, even though both go by the same name.

Net Investment Income Tax

The 3.8% net investment income tax applies once your MAGI clears $200,000 for single filers, $250,000 for married filing jointly, or $125,000 for married filing separately.⁸ For this tax, MAGI is generally equal to AGI unless you excluded foreign earned income, in which case you add that back.⁹ With no foreign exclusions, the two numbers match.

Passive Activity Rental Losses

The $25,000 allowance for actively managed rental real estate losses phases out based on a MAGI that runs in the opposite direction from most: you start with AGI and then remove several items, including taxable Social Security benefits, deductible IRA contributions, the student loan interest deduction, passive activity income or losses, the self-employment tax deduction, and the exclusion for savings bond interest used for education.¹⁰ Because items come out rather than go in, this MAGI can end up higher or lower than your AGI depending on your situation.

Medicare IRMAA Surcharges

Medicare Part B and Part D premiums are adjusted upward for higher-income beneficiaries through income-related monthly adjustment amounts. IRMAA uses your MAGI from two years earlier, so 2026 premiums are set from your 2024 return.¹¹ If a life-changing event like retirement or divorce dropped your income, you can ask for an adjustment by filing Form SSA-44 with the Social Security Administration.

Let an IRS Worksheet Do the Work

You don’t have to build MAGI from scratch. Most tax software calculates it in the background, and the IRS publishes a worksheet for each version. The ones you’re most likely to reach for:

Roth IRA contributions: Worksheet 2-1, “Modified Adjusted Gross Income for Roth IRA Purposes,” in IRS Publication 590-A. Line 10 is your MAGI.⁶
Student loan interest deduction: the Student Loan Interest Deduction Worksheet in the instructions for Schedule 1 (Form 1040).
Adoption assistance exclusion: the Modified Adjusted Gross Income Worksheet for Line 23 in the Form 8839 instructions.¹²
Savings bond interest exclusion: Form 8815, Line 9, which adds back foreign earned income exclusions, adoption assistance, and certain other items.¹³

If you use tax software, look for MAGI in the summary or review section of your return. It’s usually shown near AGI, though the label varies. One thing to watch: the software calculates the version tied to whatever credit or deduction triggered it. If you need MAGI for a different purpose — say, checking Roth eligibility when the software has only calculated it for the ACA — run that benefit’s specific worksheet.

Why It Pays to Get the Number Right

A wrong MAGI can mean claiming credits you don’t qualify for, over-contributing to a Roth IRA, or collecting more ACA premium subsidy than your income supports. If the IRS finds an underpayment tied to a MAGI error, the accuracy-related penalty is 20% of the underpaid amount, and it doubles to 40% for a gross valuation misstatement.¹⁴

Excess Roth contributions carry their own 6% excise tax for every year the excess stays in the account. Excess ACA subsidies come back through your tax return, in part or in full, when you reconcile at filing. Running your MAGI mid-year, rather than discovering the problem in April, is usually the cheapest way to keep any of that from happening.

1
Internal Revenue Service. Modified Adjusted Gross Income
2
Office of the Law Revision Counsel. 26 USC 62 – Adjusted Gross Income Defined
3
Internal Revenue Service. Form 1040 – U.S. Individual Income Tax Return (2025)
4
Healthcare.gov. How to Estimate Your Expected Income
5
Internal Revenue Service. Instructions for Form 2555 (2025)
6
Internal Revenue Service. Publication 590-A (2025)
7
Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500
8
Office of the Law Revision Counsel. 26 USC 1411 – Imposition of Tax
9
Internal Revenue Service. Topic No. 559, Net Investment Income Tax
10
Internal Revenue Service. Publication 925 (2025), Passive Activity and At-Risk Rules
11
CMS. 2026 Medicare Parts A and B Premiums and Deductibles
12
Internal Revenue Service. Instructions for Form 8839 (2025)
13
Internal Revenue Service. Form 8815 – Exclusion of Interest From Series EE and I U.S. Savings Bonds Issued After 1989
14
Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty on Underpayments