MAGI is an individual’s adjusted gross income (AGI) with certain deductions or exclusions added back, and it’s used to determine eligibility for various tax benefits and surtaxes. In practical terms, MAGI starts with your AGI (which is gross income minus specific adjustments) and then “modifies” it by adding back items like tax-exempt interest, foreign earned income exclusions, or certain deductions. This figure is critical for high-net-worth investors because it determines exposure to taxes such as the 3.8% Net Investment Income Tax (which kicks in for MAGI over $200,000 single or $250,000 joint) and eligibility for contributions or deductions (for instance, Roth IRA contributions and deductibility of traditional IRA contributions are phased out at high MAGI levels). Essentially, a high MAGI can trigger additional tax costs on investment income – including rental income or capital gains from real estate – so investors and their tax advisors often strategize to manage MAGI (through methods like real estate depreciation or income timing). For example, using real estate losses or Section 1031 exchanges to defer gains can help limit MAGI-driven taxes, aligning with an overall strategy of tax-efficient investing.