High-income investors and households often first encounter the Net Investment Income Tax when their investment income is already large enough to matter, which is usually too late to plan around it. Understanding the net investment income tax threshold, what counts as investment income, and how the tax actually works gives you the room to plan before the liability shows up on your return.
What Is the Net Investment Income Tax
The Net Investment Income Tax, or NIIT, is a federal surtax under Internal Revenue Code Section 1411 that applies on top of regular income tax for higher-income taxpayers with investment income.
The 3.8% NIIT Rate Explained
The NIIT applies a 3.8% surtax on the lesser of your net investment income or the amount your modified adjusted gross income (MAGI) exceeds the applicable threshold for your filing status. Because the tax applies to whichever figure is smaller, a taxpayer with high MAGI but modest investment income may owe little or no NIIT, while a taxpayer with large investment income just over the threshold can owe the full 3.8% on a significant amount.
Who the NIIT Applies To
The NIIT applies to individuals, estates, and trusts, though estates and trusts use a much lower, inflation-adjusted threshold of roughly $16,000 for 2026. For individuals, the tax only applies once MAGI crosses the relevant threshold, which is why it is often described as a tax that targets higher earners rather than all investors.
The Net Investment Income Tax Threshold for 2026
The net investment income tax threshold depends entirely on filing status and has stayed fixed since the tax was introduced in 2013.
MAGI Thresholds by Filing Status
The current thresholds are $200,000 for single and head of household filers, $250,000 for married couples filing jointly and qualifying surviving spouses, and $125,000 for married couples filing separately. Crossing this modified adjusted gross income threshold, even by a small amount, can expose a meaningful portion of your investment income to the 3.8% surtax.
Why These Thresholds Have Not Changed Since 2013
Unlike many parts of the tax code, these NIIT thresholds are not indexed for inflation. As wages and investment values rise over time, more households are pulled above a threshold that has not moved in over a decade, which is one reason the NIIT affects a growing share of taxpayers each year without any change in the law itself.
What Counts as Net Investment Income
Not all income counts toward the NIIT, and the distinction between included and excluded income is where most of the planning opportunity sits.
Income That Is Included
Net investment income generally includes interest, dividends, capital gains, rental and royalty income, non-qualified annuity income, and income from a trade or business that is a passive activity or involves trading financial instruments. The net investment income tax on rental and investment income can apply even to a landlord or investor who does not think of themselves as a high earner, if their MAGI happens to cross the threshold in a given year.
Income That Is Excluded
Wages, self-employment income, Social Security benefits, tax-exempt municipal bond interest, and distributions from qualified retirement plans and IRAs are all excluded from net investment income, even though they still count toward MAGI for purposes of the threshold test. Required distributions and other retirement account decisions should be coordinated with an RMD strategy so they do not unexpectedly push you over the threshold in a given year.
How the Threshold Affects High-Income Investors and Households
The practical impact of the NIIT shows up differently depending on where your income comes from.
Rental, Royalty, and Passive Business Income
Landlords and investors with significant rental, royalty, or passive business income often see the NIIT apply to that income directly, on top of regular income tax, since this income sits squarely within the included category.
Capital Gains From Selling Investments or a Business
A large one-time capital gain, such as from selling a portfolio of investments or an interest in a business, can push MAGI well above the threshold in the year of the sale. Business owners planning a sale should factor the NIIT into their overall business sale tax strategy rather than discovering the surtax after the transaction closes.
Strategies to Reduce Your Net Investment Income Tax Exposure
A handful of planning strategies to reduce NIIT exposure focus on either lowering MAGI or shifting the timing of investment income.
Timing Income and Gains Around the Threshold
Spreading capital gains across multiple years, harvesting losses to offset gains, and timing large income events can all help keep MAGI below the threshold in a given year. This kind of timing works best as part of ongoing tax planning rather than a decision made at the moment a sale or distribution happens.
Tax-Exempt and Retirement Income Planning
Shifting a portion of a portfolio toward tax-exempt municipal bonds, or managing the timing of Roth conversions, can reduce the investment income that counts toward the NIIT, though a Roth conversion itself still raises MAGI in the year it happens and needs to be modeled carefully.
Working With a CPA on Multi-Year Planning
Because the threshold is fixed and MAGI can swing year to year, a CPA in Walnut Creek who looks at your income across multiple years can time sales, distributions, and deductions to minimize how often you cross the threshold, rather than reacting to it after each tax year closes.
How Capital Tax Can Help
Capital Tax works with high-income investors and households to model how close their income is to the net investment income tax threshold and to plan sales, distributions, and portfolio decisions around it. Reach out before a major sale or distribution so the NIIT is part of the plan rather than a surprise on next year’s return.
Frequently Asked Questions About the Net Investment Income Tax
What is the net investment income tax threshold?
The threshold is $200,000 of modified adjusted gross income for single and head of household filers, $250,000 for married couples filing jointly, and $125,000 for married couples filing separately.
Does the NIIT threshold adjust for inflation?
No. The individual thresholds have remained unchanged since the tax took effect in 2013. Only the much lower threshold used for estates and trusts is adjusted for inflation each year.
Is rental income subject to the NIIT?
Yes, in most cases. Rental and royalty income generally counts as net investment income and can be subject to the 3.8% surtax once your MAGI crosses the applicable threshold.
Can retirement account withdrawals trigger the NIIT?
Retirement account distributions themselves are excluded from net investment income, but they still raise your MAGI, which can push other investment income over the threshold and expose it to the tax.
How can I reduce my net investment income tax?
Common strategies include timing capital gains and large income events, harvesting investment losses, holding some tax-exempt municipal bonds, and planning Roth conversions and retirement distributions across multiple years with a CPA.