That's where people get stuck. The return shows AGI, taxable income and total tax, but which one feeds Roth IRA eligibility, ACA credits, student loan interest or Medicare IRMAA? For Australian-based US filers, foreign income exclusions add another layer. This guide walks through the steps and flags the traps.
Key Takeaways
- MAGI has no single formula; add-backs depend on the rule being tested.
- AGI is your starting point, and its line number changes between form years.
- MAGI isn't on a W-2, and it isn't taxable income.
- Use the IRS worksheet for your purpose, and get a review if foreign exclusions apply.
Where to Find Modified Adjusted Gross Income on Form 1040
MAGI is not a printed line on Form 1040
Direct answer: Form 1040 reports AGI, not one universal MAGI figure. MAGI is calculated separately because each tax rule modifies AGI differently.
HealthCare.gov states plainly that MAGI doesn't appear as a line on your tax return. The IRS instead sets out a separate calculation for each benefit.
Line numbers shift, so confirm the form year:
| Form 1040 year | AGI | Taxable income |
|---|---|---|
| 2023 | Line 11 | Line 15 |
| 2024 | Line 11 | Line 15 |
| 2025 | Line 11a, carried to 11b | Line 15 |
Taxable income is the wrong starting point. It comes after the standard or itemised deduction (line 12e on the 2025 form), so it understates the figure most tests want. Start at AGI.
What documents should you use?
Gather the complete Form 1040, the schedules (especially Schedule 1) and the worksheet for your purpose. A W-2 or 1099 shows source income only, never MAGI.
Cross-border filers should also pull Form 2555 and check for:
- Foreign earned income exclusion
- Foreign housing exclusion or deduction
- Tax-exempt interest
- Nontaxable Social Security benefits
How to Calculate MAGI From Form 1040
Step 1: Identify the tax purpose and tax year
Decide what you're testing: Roth IRA contribution, Traditional IRA deduction, ACA Premium Tax Credit, Medicare IRMAA or student loan interest. Each has its own add-back list.
Then open the current IRS or agency guidance for that purpose. Don't borrow a generic add-back list.
Step 2: Start with AGI from Form 1040
Use the final AGI reported on the return. Schedule 1 adjustments have already been applied to it, so don't rebuild it from wages, gross income or taxable income.
Step 3: Add back only the required modifications
MAGI = AGI + the modifications required for that provision.
Depending on the rule, add-backs can include:
- Student loan interest deduction
- IRA deduction (for Roth tests)
- Foreign earned income and housing exclusions
- Foreign housing deduction
- Tax-exempt interest
- Nontaxable Social Security benefits
Not every item applies everywhere. One return can produce several different MAGI figures.
Step 4: Compare the result with the applicable rule
Match your figure against the threshold for your filing status and tax year.
For example, if you excluded foreign earned income on Form 2555, a Roth IRA test requires you to add that exclusion back to AGI. That total is your Roth MAGI.
The same return can produce a different figure for an ACA test. Always confirm with the current IRS worksheet.
AGI vs. MAGI: What Is the Difference?
How AGI is calculated
The IRS definition of AGI is gross income minus Schedule 1 adjustments, calculated before the standard or itemised deductions. On the 2025 Schedule 1, common adjustments include:
- Educator expenses (line 11)
- HSA deduction (line 13)
- Deductible part of self-employment tax (line 15)
- Student loan interest (line 21)
Line 26 totals them and carries to Form 1040 line 10.
How MAGI is calculated
MAGI is AGI modified for a specific purpose. Some deductions that lowered AGI get added back. Others stay out. There's no universal exclusion list, since an item excluded in one calculation may be added back in another.
MAGI comes before the standard deduction
The sequence runs like this:
- Gross income minus adjustments gives AGI.
- Purpose-specific add-backs give MAGI.
- The standard or itemised deduction then reduces AGI to taxable income.
AGI and MAGI can be identical when no add-backs apply. They diverge with excluded foreign income or tax-exempt interest. A low taxable income doesn't mean a low MAGI.
How MAGI Changes by Tax Purpose
Roth and Traditional IRA rules
IRS Publication 590-A uses Worksheet 1-1 for the Traditional deduction and Worksheet 2-1 for Roth contributions. Each test uses its own MAGI rules. For 2026, the Roth phase-out is $153,000 to $168,000 for single filers and $242,000 to $252,000 for joint filers.
Cross-border caution: both worksheets add back foreign earned income and housing exclusions. Excluded foreign earned income still is not IRA compensation, so clearing the MAGI test alone does not make you eligible to contribute.
Medicare IRMAA
The SSA formula is AGI plus tax-exempt interest. For 2026, it generally uses 2024 income. The first surcharge tier starts above $109,000 for individuals and $218,000 for joint filers.
If your income has dropped after a life-changing event, file Form SSA-44 to request a new determination. The IRMAA figure can differ from your Roth or ACA MAGI.
ACA Premium Tax Credits and other benefits
ACA MAGI is AGI plus excluded foreign income, tax-exempt interest and nontaxable Social Security (not SSI). Form 8962 Worksheet 1-1 does the calculation. Marketplace enrolment also requires living in the United States, which US citizenship alone doesn't satisfy.
Student loan interest uses yet another MAGI definition. For 2026 the deduction phases out between $85,000 and $100,000 for filers who are not married filing jointly, and $175,000 to $205,000 for joint filers. Identify the exact form or worksheet before you calculate.
Common Mistakes, Ways to Lower MAGI, and Next Steps
Common calculation mistakes
- Treating W-2 wages, gross income or taxable income as MAGI
- Subtracting the standard deduction first
- Applying one MAGI formula to every program
- Using the wrong tax year
- Overlooking a foreign exclusion or tax-exempt amount
How to lower MAGI legally
Reducing AGI can reduce some MAGI figures, but not every deduction survives every add-back. For 2026, options that can lower AGI include:
- Pre-tax 401(k) deferrals (base limit $24,500)
- Traditional IRA contributions ($7,500; catch-up $1,100 at 50+), though some MAGI tests add the deduction back
- HSA contributions ($4,400 self-only, $8,750 family)
Confirm eligibility first. Also note the foreign tax credit reduces tax liability, not AGI.
When professional review is worthwhile
Australian-based US filers face worldwide-income reporting, foreign exclusions and retirement accounts all at once. A generic online calculator won't handle that well. VJM Global provides US individual return preparation (Form 1040) and international tax support, and can review these calculations. No outcome is guaranteed, but a second look beats guessing.
Frequently Asked Questions
How do I calculate my modified adjusted gross income (MAGI) from Form 1040?
Start with AGI from your Form 1040. Then add only the modifications the specific rule and worksheet require.
How do I calculate MAGI for IRMAA?
Add tax-exempt interest to AGI. For 2026, SSA generally uses 2024 income, so check the look-back year in its guidance.
What is the difference between AGI and MAGI?
AGI is the return figure calculated before the standard deduction. MAGI is AGI modified for a particular eligibility or surcharge test.
Is MAGI calculated before or after the standard deduction, and what income is excluded?
Before. It starts from AGI, which precedes the standard deduction. What's excluded or added back depends on the specific provision.
How can I lower my MAGI?
Actions that reduce AGI, such as pre-tax retirement or HSA contributions, can lower some MAGI figures. Add-backs vary, so check the rules before acting.
Where is MAGI on Form 1040?
It isn't a standalone line. Find AGI (line 11a on the 2025 form), then complete the relevant IRS worksheet.
