Modified Adjusted Gross Income (MAGI)
AGI with certain deductions added back; the income figure that drives ACA subsidies, IRMAA, and contribution limits.
MAGI is your adjusted gross income with specific items added back (the additions vary by which rule is using it). It's the income measure behind many of the most consequential thresholds in retirement planning: ACA subsidy eligibility, Medicare IRMAA tiers, Roth IRA contribution limits, and more.
Because so much keys off MAGI, controlling it is central to early-retirement tax planning. The same dollar of Roth withdrawal versus traditional withdrawal, or return-of-basis versus realized gain, can land very differently in MAGI — which is why the source of your retirement cash flow, not just the amount, shapes your subsidies and surcharges.
This definition is general information to help you understand a term, not financial, tax, or legal advice. Figures that change year to year (limits, thresholds, rates) should be confirmed against current official sources. For guidance on your situation, a licensed fee-only fiduciary is the right next step.