NIIT Calculator

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3.8% surtax • Investment income

Filing status

Modified AGI

Net investment income ⓘ

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Enter your income to check the 3.8% NIIT

How the NIIT Calculator Works

Enter your filing status and MAGI.
Enter your net investment income.
See your 3.8% surtax — charged on the lesser of your investment income or the amount your MAGI exceeds the threshold.

What Is the Net Investment Income Tax?

The NIIT is a 3.8% surtax on investment income for higher earners, on top of regular income and capital-gains tax. It applies to the lesser of (a) your net investment income or (b) the amount your modified AGI exceeds the threshold: $200,000 single, $250,000 married filing jointly, $125,000 married filing separately. These thresholds are not inflation-adjusted, so more taxpayers owe it over time.

Net investment income includes taxable interest, dividends, capital gains, rental and royalty income, and annuities — but not wages, Social Security, or tax-exempt municipal bond interest. Estimate only; not tax advice.

NIIT FAQ

Who pays the 3.8% NIIT? ▾

Taxpayers with modified AGI above $200,000 (single) or $250,000 (joint) who also have net investment income. It's charged on the lesser of the two excess amounts.

What counts as net investment income? ▾

Interest, dividends, capital gains, rental/royalty income and annuities. Wages, self-employment income, Social Security and municipal-bond interest are excluded.

How can I reduce NIIT? ▾

Lower MAGI or investment income — via tax-loss harvesting, municipal bonds, retirement-account contributions, installment sales, or spreading large gains across years.