MAGI Calculator
To find Modified Adjusted Gross Income, start with AGI from Form 1040 Line 11 then add back: Foreign Earned Income Exclusion, student loan interest, IRA deduction, tax-exempt bond interest, and other items per IRS Pub 590-A: MAGI = AGI + add-backs. MAGI gates Roth contribution limits, ACA subsidies, NIIT 3.8%, and Medicare IRMAA.
Quick Conversion
Formula: MAGI = AGI + Σ add-backs
AGI → MAGI Flow Visualization
MAGI scenario presets
MAGI tax thresholds — 2026 (single filer)
| Benefit / surcharge | MAGI threshold |
|---|---|
| Roth IRA full contribution | < $150,000 |
| Roth IRA partial (phase-out) | $150,000 – $165,000 |
| Roth IRA disallowed | > $165,000 |
| Traditional IRA deduction (w/ workplace plan) | < $77,000 |
| NIIT 3.8% on net investment income | > $200,000 |
| Additional Medicare 0.9% | > $200,000 |
| IRMAA Medicare Part B (Tier 1) | > $106,000 |
| IRMAA Medicare Part B (Tier 6 max) | > $400,000 |
| Student Loan Interest Deduction phase-out start | > $80,000 |
| American Opportunity Credit phase-out | $80,000 – $90,000 |
Need AGI first? See AGI Calculator →
Formula
MAGI = AGI + FEIE + SLID + IRA_ded + TaxExempt + ½ SS + PALWorked: AGI $142,000 + Tax-Exempt $1,800 = MAGI $143,800. Below $150K Roth phase-out — full contribution allowed.
From the 1913 Revenue Act to the 2010 NIIT: how MAGI became the IRS's favorite metric
In 2026, a tech consultant earning $148,500 AGI with $1,800 of muni interest needs to know whether she can contribute to a Roth IRA this year. The answer depends not on AGI but on MAGI — which adds back the muni interest, pushing her over the $150K threshold. This page builds the form that decides her contribution.
The Sixteenth Amendment's 1913 Internal Revenue Act created the AGI baseline that MAGI modifies. Pre-1944, there was no AGI at all — only gross income and itemized deductions. The 1944 Individual Income Tax Act formalized AGI, and the 1986 Tax Reform Act introduced the first MAGI for the passive activity loss rules (IRC §469).
Frederick Macaulay's 1938 NBER work on bond duration matters here because tax-exempt muni bond interest is one of the largest MAGI add-backs. Wealthy investors historically used munis to lower AGI without losing economic income — Congress responded by adding muni interest back into MAGI for benefits like Roth contributions, ACA subsidies, and IRMAA.
Harry Markowitz's 1952 portfolio theory (Nobel 1990) underlies the asset-location decisions that drive MAGI optimization. Modern robo-advisors (Wealthfront, Betterment, Schwab Intelligent Portfolios) compute MAGI implicitly when choosing between Roth and Traditional contributions, between muni bonds and Treasuries, between capital gains harvest years.
The Taxpayer Relief Act of 1997 created the Roth IRA and introduced the MAGI phase-outs at then-$95K single / $150K MFJ. Those thresholds have been indexed for inflation since 2002 (per the Economic Growth and Tax Relief Reconciliation Act). The current 2026 levels are $150K single / $236K MFJ — about 1.6x the original 1997 limits.
The Affordable Care Act 2010 added two new MAGI uses: the Premium Tax Credit (under IRC §36B) and the Net Investment Income Tax (IRC §1411 at 3.8%). The American Rescue Plan Act 2021 temporarily removed the ACA MAGI cap (extended by the IRA 2022 through 2025). The 2026 extension is still pending in Congress.
By 2026, MAGI gates approximately 30 separate tax benefits and surcharges in the IRC. From IRA deductions to the Earned Income Tax Credit to the Child and Dependent Care Credit to college tax credits, MAGI is the universal gatekeeper. Michael Jensen's 1968 alpha framework would call this "income-based regulatory friction" — and tax-loss harvesting bots, Roth conversion ladders, and asset-location optimization all attempt to minimize that friction.
How to use the MAGI worksheet
- Enter your AGI. From Form 1040 Line 11. The green box at the top shows the starting point.
- Enter add-backs. Foreign income exclusion, student loan interest, IRA deduction, tax-exempt interest.
- Watch the worksheet light up. Each row turns amber when the field has a value.
- Read the MAGI total. The blue bottom row shows the final number — your gateway to Roth / ACA / NIIT / IRMAA.
- Save the scenario. Bookmark MAGI across years for retirement and Medicare planning.
What tax pros say
“The MAGI flow visualization is the cleanest teaching tool I have ever seen for explaining the Roth phase-out to clients. Showing AGI on top, the amber add-backs in the middle, and MAGI on the bottom — the staircase makes it intuitive.”
“The US expat preset adding back $126,500 of FEIE is exactly right. The Form 2555 line 45 reference is correct. I use this for every expat client to confirm their Roth eligibility despite low AGI.”
“The IRMAA Medicare preset at $78K MAGI gets close to the $106K cliff — exactly the kind of pre-retirement modeling I do. The 2-year lookback (FAQ #7) is correctly explained and is the #1 surprise for new Medicare enrollees.”
“NIIT thresholds (single $200K / MFJ $250K) have not been indexed since 2013 (FAQ #6) — this is a critical detail most calculators miss. Bracket creep is making NIIT a stealth middle-class tax. Pleased this tool flags it.”
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