Net Investment Income Tax (NIIT) Calculator (2025)

NIIT is an additional 3.8% tax on net investment income above threshold amounts. This page helps estimate exposure.

2025 Thresholds

For most taxpayers the NIIT applies to modified adjusted gross income (MAGI) above $200,000 single, $250,000 MFJ, and $200,000 for HOH — confirm IRS updates for 2025.

How It Works

  1. Calculate MAGI and determine excess over threshold
  2. Compute net investment income (interest, dividends, capital gains, rental income)
  3. NIIT = 3.8% × the smaller of (net investment income) or (MAGI - threshold)

Use our NIIT calculator on-site to estimate the tax liability. This calculator page will be interactive in the final build.

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