Net Investment Income Tax (NIIT)

The Net Investment Income Tax is a 3.8% federal tax on investment income (including capital gains and rental income) for higher-income taxpayers — applicable above $200K MAGI for single filers and $250K for married filing jointly.

What it means

IRC § 1411 imposes a 3.8% tax on net investment income for taxpayers whose modified adjusted gross income (MAGI) exceeds specified thresholds ($200K single / $250K MFJ, not indexed for inflation). Investment income subject to NIIT includes interest, dividends, capital gains, rental income (for non-real-estate-professional taxpayers), and royalties.

Real estate professionals under IRC § 469(c)(7) may exclude rental income from NIIT if rental activity is non-passive to them. For most CRE investors, NIIT applies on top of ordinary federal income tax, adding meaningfully to the marginal rate on rental and capital gain income.