Net Investment Income Tax (NIIT) Calculator

Calculate the 3.8% Net Investment Income Tax for high earners. NIIT applies to investment income when your Modified Adjusted Gross Income (MAGI) exceeds certain thresholds.

NIIT Calculator

Enter your net investment income and MAGI to calculate your NIIT obligation.

What is NIIT? The Net Investment Income Tax is a 3.8% tax on the lesser of your net investment income or the amount your MAGI exceeds the threshold ($200,000 single, $250,000 married filing jointly).

Includes interest, dividends, capital gains, rental income, royalties, etc.

Your AGI plus certain adjustments (foreign earned income exclusion, etc.)

Understanding NIIT

What is Net Investment Income? Includes interest, dividends, capital gains, rental income, royalties, non-qualified annuities, and income from businesses in which you don't materially participate.

MAGI Thresholds (2025):

  • Single or Head of Household: $200,000
  • Married Filing Jointly: $250,000
  • Married Filing Separately: $125,000

Important: NIIT is in addition to regular income tax. It must be included when calculating your quarterly estimated tax payments.