Net investment income tax calculator

Find out whether you owe the 3.8% net investment income tax and how much, with the lesser-of rule worked out.

By the Calcist team · Checked against known answers · Updated October 29, 2026

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Estimates for planning, not financial, tax or legal advice. Figures use US rules unless the page says otherwise.

Next: Need the regular tax on the gains too? Use the capital gains tax calculator or the qualified dividends worksheet.

What the net investment income tax is

The net investment income tax (NIIT) is an extra 3.8% federal tax on investment income for people with higher incomes. It's figured on Form 8960 and added to your regular income tax. It applies to the smaller of two amounts: your net investment income, or how much your modified adjusted gross income (MAGI) is over the threshold for your filing status.

Filing status	MAGI threshold
Married filing jointly or qualifying surviving spouse	$250,000
Married filing separately	$125,000
Single or head of household	$200,000

These thresholds are written into the law and aren't adjusted for inflation, so the same numbers apply in 2025 and 2026.

How it's calculated

NIIT = 3.8% × smaller of (net investment income, MAGI − threshold)

Net investment income includes interest, dividends, capital gains, rents and royalties, non-qualified annuities, and income from passive businesses or from trading financial instruments, minus the expenses that go with them. It doesn't include wages, self-employment income from a business you actively run, unemployment, Social Security, tax-exempt interest, or the part of a home-sale gain you can exclude.

Worked example

A single filer has MAGI of $250,000, including $80,000 of dividends and capital gains. MAGI is $50,000 over the $200,000 threshold. The smaller of $80,000 and $50,000 is $50,000, so the NIIT is 3.8% × $50,000 = $1,900. If the same person had only $30,000 of investment income, the tax would be 3.8% × $30,000 = $1,140.

Limitations

MAGI for the NIIT is AGI plus foreign earned income you excluded; it isn't the same MAGI used for IRAs or the SALT cap.
Gains inside IRAs and 401(k)s aren't net investment income, but taxable distributions from them do raise your MAGI.
Estates and trusts use a different threshold and aren't covered here.
To see the regular tax on gains as well, use the capital gains tax calculator.

Sources

IRS Topic 559, Net investment income tax – 3.8%, the lesser-of rule, thresholds, what's included and excluded
Form 8960 and instructions – the form used to figure it

How we checked this

Before every update, this calculator is run in a real browser with these known answers, and it must match all of them:

Single, MAGI $250,000, $80,000 NII: 3.8% × $50,000 = $1,900 ✓
Joint, MAGI $300,000, $30,000 NII: 3.8% × $30,000 = $1,140 ✓
Separately, MAGI $150,000: 3.8% × $25,000 = $950 ✓
Single, MAGI $190,000 (under $200,000): no NIIT ✓

Last checked October 26, 2026. Spotted something wrong? The math is done in your browser with the formula shown on this page, so you can check any result by hand.

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Questions people ask

What is the net investment income tax?

A 3.8% federal tax on the smaller of your net investment income or the amount your MAGI is over $200,000 (single), $250,000 (joint) or $125,000 (separately).

Does the net investment income tax apply to wages?

No. Wages, unemployment and income from a business you actively run aren't net investment income, although wages do count toward the MAGI threshold.

Is the NIIT threshold adjusted for inflation?

No. The $200,000, $250,000 and $125,000 thresholds are fixed in the law, so more people pay it over time.

Does selling my home trigger the 3.8% tax?

Only on gain you can't exclude. The excluded part of a principal-residence gain isn't net investment income.

What form is the NIIT reported on?

Form 8960. The result goes on your Form 1040 with your other taxes.

Related calculators

Capital gains tax calculator2026 tax on short- and long-term gains, with the 3.8% NIIT.Qualified dividends and capital gain tax worksheetThe IRS worksheet for 0%, 15% and 20% rates, all 25 lines.AGI calculatorAdjusted gross income and taxable income, line by line.Income tax calculator2026 federal income tax, brackets, marginal and effective rate.