How the MAGI Calculator works
Modified Adjusted Gross Income (MAGI) is a figure the IRS uses instead of plain Adjusted Gross Income (AGI) to test eligibility for a range of tax benefits. It starts with your AGI — the number near the bottom of page 1 of Form 1040 — and adds back certain deductions and exclusions the tax code let you subtract or exclude in the first place. The idea is to measure income before those specific breaks, so the eligibility test cannot be gamed simply by taking the deduction.
The formula
This calculator uses the common, broad version of the MAGI formula that applies to most individual filers:
MAGI = AGI + tax-exempt interest + excluded foreign earned income and housing costs + non-taxable Social Security benefits + traditional IRA deduction claimed + student loan interest deduction claimed
Each add-back item restores income that AGI already removed. Tax-exempt interest (for example, from municipal bonds) never appears in AGI at all, so it is added back in full. The foreign earned income exclusion and the IRA and student loan interest deductions are amounts you subtracted to arrive at AGI, so MAGI adds them back. For most taxpayers who have none of these items, MAGI and AGI come out exactly equal.
Worked example
Take an AGI of $75,000 with $1,200 of tax-exempt municipal bond interest and a $1,000 traditional IRA deduction claimed, and no other add-back items. Total add-backs are $1,200 + $1,000 = $2,200, so MAGI = $75,000 + $2,200 = $77,200. That is roughly a 2.9% increase over AGI — enough to matter if a benefit's income limit sits between $75,000 and $77,200.
Why MAGI has more than one definition
The IRS does not use one single MAGI formula for everything. The add-back list used to test Roth IRA contribution eligibility and the traditional IRA deduction limit is close to — but not always identical to — the version used for the Net Investment Income Tax, the ACA premium tax credit, or Medicare's Income-Related Monthly Adjustment Amount (IRMAA). This calculator applies the widely used general-purpose version above; always confirm against the specific IRS worksheet or instructions tied to the benefit you are claiming before relying on the number for a filing decision.
Getting accurate inputs
- Pull your AGI directly from your prior-year return or current tax software rather than estimating it — a few hundred dollars of error carries straight through to MAGI.
- Only include amounts that actually apply to your return; leave an item at $0 rather than guessing.
- Enter dollar amounts, not percentages, for every field on this calculator.