MAGI Calculator
Estimate your modified adjusted gross income in dollars. Start with AGI (Form 1040, line 11), then add back tax-exempt interest, excluded foreign earned income, non-taxable Social Security, and IRA or student-loan deductions — the calculator shows MAGI under the ACA, Medicare IRMAA, and Roth IRA definitions at once.
Example: with Adjusted gross income (AGI, $) 75000 · Tax-exempt interest ($) 500 · Excluded foreign earned income ($) 0 · Non-taxable Social Security ($) 0 · IRA + student loan interest deductions ($) 2500 → MAGI — ACA / premium credit: $75,500.
- MAGI — Medicare IRMAA$75,500
- MAGI — Roth IRA limits$77,500
- Add-backs entered$3,000 added back in total
Computed by the calculator below using its default values. Change any input to see your own numbers.
There is no single MAGI — each program defines its own add-backs to AGI. This tool computes the three most-used versions from the same inputs.
Why there is no single MAGI
MAGI is not a line on Form 1040 — it is a recipe each program defines for itself, always starting from adjusted gross income (line 11) and adding back specific items. The ACA marketplace adds tax-exempt interest, excluded foreign income, and the non-taxable part of Social Security. Medicare's IRMAA surcharge adds only tax-exempt interest. The Roth IRA worksheet instead restores deductions you took — traditional IRA contributions and student loan interest — plus foreign income exclusions.
That is why the same taxpayer can have three different MAGIs in the same year. Enter each add-back that applies to you and read the line that matches the decision you are making: subsidy eligibility, Medicare premiums, or Roth contribution room. For most people with no foreign income and no municipal-bond interest, MAGI simply equals AGI.
How it’s calculated
MAGI for ACA premium credits = AGI + tax-exempt interest + excluded foreign earned income + non-taxable Social Security benefits (the healthcare.gov definition). MAGI for Medicare IRMAA = AGI + tax-exempt interest (SSA definition, applied to your return from two years prior). MAGI for Roth IRA limits = AGI + excluded foreign earned income + traditional IRA and student-loan-interest deductions claimed, a simplified version of the IRS Publication 590-A worksheet. Blank add-backs count as zero.
An educational estimate, not tax advice — the model includes only the add-backs listed above and omits rarer ones (excluded savings-bond interest, employer adoption benefits, foreign housing amounts), so confirm any close-to-the-limit answer with a tax professional or the IRS worksheets.
Which add-backs count for which MAGI
| Program | Starts from | Add-backs |
|---|---|---|
| ACA premium credit / Medicaid | AGI | Tax-exempt interest, excluded foreign income, non-taxable Social Security |
| Medicare IRMAA surcharge | AGI from 2 years prior | Tax-exempt interest |
| Roth IRA contribution limit | AGI | IRA deduction, student loan interest, foreign income exclusions, a few rarer items |
| Traditional IRA deduction | AGI | Similar to Roth, but the IRA deduction itself is not added back |
Definitions: healthcare.gov (ACA), SSA.gov (IRMAA), IRS Publication 590-A (IRA worksheets).
Common mistakes
- Starting from taxable income (line 15) instead of AGI (line 11) — MAGI builds on AGI, before the standard deduction.
- Assuming one MAGI number works for every program — the ACA, IRMAA, and Roth definitions add back different items.
- Forgetting IRMAA's two-year lookback: 2026 Medicare premiums are set by your 2024 return.
- Mishandling Roth conversions — conversion income raises MAGI for ACA and IRMAA, but is excluded when testing the Roth contribution limit.
Frequently asked questions
What is the MAGI formula?
MAGI = AGI + program-specific add-backs. For ACA subsidies: AGI + tax-exempt interest + excluded foreign income + non-taxable Social Security. For Medicare IRMAA: AGI + tax-exempt interest. For Roth IRA limits: AGI + IRA and student-loan-interest deductions + foreign income exclusions.
Where do I find my AGI?
On Form 1040, line 11. Tax-exempt interest is on line 2a, total Social Security on line 6a with the taxable part on 6b — the non-taxable part is 6a minus 6b.
Is MAGI shown anywhere on my tax return?
No, and that surprises people — the IRS never prints a MAGI line because each benefit computes its own version. You always derive it from AGI plus the add-backs the specific program lists.
Why does Medicare use income from two years ago?
IRMAA is based on the most recent return the IRS has fully processed, so 2026 premiums use 2024 MAGI. If your income has dropped since (retirement, divorce, death of a spouse), you can ask SSA to reconsider using form SSA-44.
Can I rely on this for tax decisions?
Treat it as an educational estimate. It covers the common add-backs but omits rare ones, and eligibility cliffs make small errors expensive — if you are near an IRMAA bracket, subsidy cutoff, or Roth phase-out, confirm with a CPA or the IRS worksheet before acting.