NIIT CALCULATOR · RUNS IN YOUR BROWSER · NOTHING UPLOADED

Will the 3.8% investment surtax hit you, and what moves it?

Type your income and investment income. The tool fills in Form 8960, shows how far your MAGI is over the threshold, prices an extra gain, compares realizing it in one year against two, and shows what a $10,000 cut in MAGI is worth.

Arithmetic on assumptions you type. Not tax, legal or financial advice. The example figures are placeholders, not your return; the thresholds are statutory and not inflation-indexed.

1. Income that is not investment income

2. Investment income

3. Filing status and what-if

Questions people ask

What is the net investment income tax (NIIT)?

A 3.8% federal surtax on the lesser of your net investment income or the amount your modified adjusted gross income exceeds a threshold: $200,000 for single and head of household, $250,000 for married filing jointly, $125,000 for married filing separately. It is reported on Form 8960 and added to your Form 1040 tax.

Is the $200,000 threshold indexed for inflation?

No. The thresholds are written into the statute and have never been adjusted, so each year more households cross them as wages and asset prices rise.

What counts as net investment income?

Interest, dividends, capital gains, passive rental and royalty income, annuity income and income from passive businesses or trading in financial instruments, less deductions properly allocable to them. Wages, active business income, Social Security, tax-exempt interest and qualified retirement plan distributions are not NII.

Do retirement withdrawals and Roth conversions trigger it?

The withdrawal or conversion itself is not net investment income, but it raises your MAGI. That can push you over the threshold so that your existing investment income becomes taxable at 3.8%. Enter it in the wages box to see the effect.

How can I reduce the NIIT?

You can lower MAGI (pre-tax retirement or HSA contributions, qualified charitable distributions), spread a large gain over two tax years, harvest losses, or hold income in tax-exempt bonds or retirement accounts. The splitting and lever sections of the result put numbers on these for your figures.

Is this tax advice?

No. It is arithmetic on the figures you type. Figures such as the gain on a home sale exclusion, passive-activity status, and estimated-tax safe harbors need a professional. Verify with Form 8960 instructions and IRS Topic 559.

Not decided

Whether your rental or business income is passive, the home-sale exclusion, trader status, estates and trusts (different thresholds), state taxes, the interaction with the additional 0.9% Medicare tax on wages, estimated-tax safe harbors, and whether a given strategy is right for your whole return. Rates and thresholds can change by law.

Related tools: the tax-loss harvesting calculator, the depreciation recapture calculator and the estimated tax penalty calculator.