Net Investment Income Tax (NIIT): What Triggers It and How to Plan

The 3.8% surtax is driven by two moving parts—net investment income and modified adjusted gross income. Good planning has to manage both.

July 16, 2026

The Net Investment Income Tax is easy to underestimate because it rarely appears in a quoted investment return or a headline capital-gains rate. It sits on top of the regular income tax and applies when two conditions meet in the same year: you have net investment income, and your modified adjusted gross income exceeds the threshold for your filing status.

For 2026, the rate remains 3.8%. The thresholds remain $250,000 for married couples filing jointly and qualifying surviving spouses, $200,000 for single and head-of-household filers, and $125,000 for married taxpayers filing separately. Those individual thresholds are fixed in the statute and are not indexed for inflation.^1,2 That last point matters. The tax has applied since 2013, and a threshold that does not move gradually reaches more households as wages, retirement distributions, rents, and asset values rise.

I view NIIT as a calendar-management tax as much as an investment tax. A household can owe it in an ordinary year because wages and portfolio income cross the line together. It can also appear suddenly because of one large stock sale, the sale of investment real estate, a business transaction, a Roth conversion, or a required distribution that pushes modified adjusted gross income higher. The investment income may be the taxable base, but another source of income can be what opens the gate.

The calculation for an individual is 3.8% of the lesser of two amounts: net investment income for the year, or modified adjusted gross income above the applicable threshold. In shorthand, the tax is 3.8% multiplied by the smaller of net investment income and excess MAGI.¹

MAGI for most taxpayers is simply adjusted gross income. The main statutory adjustment adds back certain foreign earned income excluded under Section 911, with additional rules for some controlled foreign corporations and passive foreign investment companies.² The standard deduction and most itemized deductions do not reduce AGI, so they generally do not lower the NIIT threshold calculation.

Figure 1 shows how sharply the 2026 thresholds differ by filing status. It also shows why fiduciary income-tax planning deserves special attention. For a nongrantor estate or trust, NIIT generally applies to the lesser of undistributed net investment income or adjusted gross income above the point where the highest trust income-tax bracket begins. In 2026, that point is only $16,000.^1,3 Grantor trusts, charitable remainder trusts, and several other trust types follow different rules, so the label on the trust agreement is not enough to determine the result.

The lesser-of rule limits the tax, but it creates outcomes that are not intuitive. Consider a married couple filing jointly with $300,000 of MAGI and $80,000 of net investment income. Their MAGI exceeds the $250,000 threshold by $50,000, so NIIT applies to $50,000 rather than the full $80,000. The tax is $1,900. If the same couple has $500,000 of MAGI and the same $80,000 of net investment income, the excess MAGI is $250,000, so the smaller number is now the full $80,000 of net investment income. Their NIIT is $3,040. Figure 2 compares those outcomes with a household that remains below the threshold.

This is the central planning lesson: reducing MAGI by one dollar can reduce NIIT when excess MAGI is the limiting side of the formula, while reducing net investment income by one dollar can help when net investment income is the limiting side. We need to know which side is binding before choosing a strategy.

Figure 1: The 2026 NIIT thresholds by filing status. The estate and trust threshold follows the start of the highest fiduciary income-tax bracket.

Figure 2: NIIT is 3.8% of the lesser of net investment income or MAGI above the filing threshold. Examples are illustrative.

Net investment income generally includes taxable interest, ordinary and qualified dividends, nonqualified annuity income, royalties, rents, and net gain from property such as stocks, bonds, investment funds, digital assets, a second home, and investment real estate. It also includes income from a trade or business that is passive to the taxpayer and income from a business trading financial instruments or commodities. Certain properly allocable expenses reduce gross investment income in arriving at the net amount.^1,2,4

The word “net” is important. Capital losses can offset capital gains, and deductible rental or royalty expenses can reduce the related income. Investment interest and other specifically allowable expenses may also reduce the NIIT base, although the tax law does not permit every portfolio-related cost to be deducted. Form 8960 is where the categories, allocations, and limitations are reconciled.⁴

Several common income sources are not themselves net investment income. Wages, unemployment compensation, Social Security benefits, operating income from a nonpassive business, most self-employment income, tax-exempt municipal-bond interest, and distributions from qualified retirement plans and IRAs are generally excluded.² The exclusion can be misleading, however. A taxable IRA distribution or Roth conversion is not net investment income, but it increases AGI and can cause dividends, interest, rents, or capital gains to become subject to NIIT. The same interaction can occur when wages, bonuses, or nonqualified stock-option income push MAGI above the threshold.

A principal residence receives another important distinction. Gain excluded from gross income under Section 121—generally up to $250,000 for an eligible single owner or $500,000 for an eligible married couple filing jointly—is also excluded from net investment income. Recognized gain above the available exclusion can enter the NIIT calculation.²

Active business owners need a fact-specific review. Operating income from a business in which the owner materially participates is generally outside net investment income, but rent, portfolio income inside the entity, and gain on the sale of partnership interests or S corporation stock can require special adjustments. Material participation, the character of the underlying assets, and the deal structure all matter.⁴ “I work in the business” is a starting fact, not a complete NIIT conclusion.

The most obvious group is a high-earning household with a meaningful taxable portfolio. Once wages or other ordinary income already exceed the threshold, the next dollar of net investment income may carry the 3.8% surtax in addition to regular tax. A 20% long-term capital-gains rate can therefore become a 23.8% federal rate before state tax, while qualified dividends can face the same combined federal rate.

The second group is anyone approaching a concentrated realization year. Selling appreciated stock, exercising equity compensation and selling shares, liquidating investment real estate, receiving a large partnership distribution, or selling a passive business interest can pull several years of gains into one return. Installment treatment may spread eligible gain over the years payments are received, but it is unavailable for some assets, depreciation recapture can be recognized immediately, and buyer-credit risk becomes part of the tax decision.^4,5

Retirees near the threshold are a third group. Required minimum distributions and taxable retirement withdrawals are not net investment income, yet they can raise MAGI enough to expose otherwise ordinary portfolio income to NIIT. Roth conversions create the same current-year interaction even when they improve the long-term plan. A surviving spouse can be especially vulnerable because the joint threshold of $250,000 becomes a $200,000 single threshold, while the household may still hold most of the same investments and receive many of the same distributions.

Passive real-estate investors and limited partners also belong on the watch list because rents, passive business income, and sale gains are common NIIT items. Real-estate-professional status by itself is not a universal exemption; material participation and whether the activity rises to a qualifying trade or business must also be evaluated under the regulations and the taxpayer’s facts.⁴

Trustees and beneficiaries should review nongrantor trusts before year-end. With a 2026 threshold of $16,000, a trust can reach the NIIT zone quickly. Distributing income may shift some tax to beneficiaries, but the distributable-net-income rules, trust terms, state law, beneficiary tax positions, and the purpose of the trust all have to support the decision. Tax savings should not override asset protection or the grantor’s intent.

Finally, 2026 has a special watch item for investors with legacy Qualified Opportunity Fund deferrals. Under the pre-2027 rules, remaining deferred gain is generally included at the earlier of an inclusion event or December 31, 2026. The 2025 tax law made the Opportunity Zone program permanent for later investments, but it did not erase the December 31, 2026 inclusion date for qualifying investments made under the prior regime.⁶ Depending on the character of the original gain and the taxpayer’s other income, that inclusion may materially increase NIIT and estimated-tax exposure.

The first step is to build a two-column projection before acting: expected MAGI in one column and expected net investment income in the other. That sounds basic, but it prevents a common mistake—using a strategy that reduces taxable income without changing either side of the NIIT formula. An itemized charitable deduction, for example, can lower regular taxable income, but it generally does not lower AGI. By contrast, donating a long-held appreciated security directly to a qualified charity or donor-advised fund can avoid realizing the embedded gain and remove the asset’s future income from the portfolio. The charitable deduction has its own percentage limits, substantiation rules, and, beginning in 2026, an itemized-deduction floor; the NIIT benefit comes primarily from not selling the appreciated asset first.⁷

Tax-loss harvesting is another direct way to reduce the net-investment-income side. Realized capital losses offset realized capital gains, and an individual may generally deduct up to $3,000 of excess net capital loss against other income, with unused losses carried forward.⁸ The strategy must respect the wash-sale rules and remain consistent with the portfolio. A tax loss is useful only when the replacement exposure and long-term investment plan still make sense.

Gain timing also matters. Spreading discretionary sales across tax years, coordinating a sale with a lower-income year, using eligible installment treatment, or completing a properly structured Section 1031 exchange of qualifying real property can defer recognition and reduce a single-year spike.⁵ Deferral is not the same as elimination. Future rates, interest income on an installment note, liquidity, transaction risk, basis, depreciation recapture, and estate-planning objectives all belong in the comparison.

The MAGI side can often be managed through above-the-line deductions and pretax savings. In 2026, an employee can generally defer up to $24,500 into a 401(k), 403(b), or most governmental 457 plans before applicable catch-up rules, while eligible HSA contribution limits are $4,400 for self-only coverage and $8,750 for family coverage.^9,10 These limits are not a recommendation to maximize every account, and some catch-up contributions for higher-wage employees must be Roth rather than pretax in 2026. The point is to use every available deduction intentionally when it fits the cash-flow and retirement plan.

Account location can reduce recurring net investment income over time. Interest, high-turnover strategies, and other tax-inefficient assets may be better housed in tax-deferred or tax-free accounts when the overall investment allocation allows it. Taxable retirement-account distributions are excluded from net investment income, although they can raise MAGI later. Roth-qualified distributions generally avoid both sides of the NIIT test. Tax-exempt municipal interest is also excluded from net investment income and generally from MAGI, but credit quality, duration, state tax, and after-tax yield still determine whether it belongs in the portfolio.²

For an IRA owner age 70 1/2 or older who is charitably inclined, a qualified charitable distribution can be particularly efficient because an eligible direct transfer to charity is excluded from income and can count toward an RMD. The 2026 annual exclusion limit is $111,000 per eligible IRA owner.¹¹ Unlike writing a check and claiming an itemized deduction, the QCD can keep the distribution out of AGI, which can preserve room below the NIIT threshold. The receiving organization, IRA type, timing, and post-age-70 1/2 deductible-contribution offset rules must be checked before using it.

Roth conversions deserve the opposite warning. A conversion may reduce future RMDs and future MAGI, which can lower lifetime NIIT exposure, but the conversion itself increases current MAGI and can trigger NIIT on existing investment income. I would not evaluate a conversion by its ordinary-income bracket alone. The analysis should include NIIT, Medicare income-related premiums, charitable plans, capital gains, the surviving-spouse tax profile, and the expected distribution path over several years.

NIIT is separate from the 0.9% Additional Medicare Tax. A high-income household can owe both in the same year—the additional Medicare tax on wages or self-employment income and NIIT on investment income—even though the same dollar of income is not taxed by both regimes.² The filing thresholds are similar, which is one reason the two are often confused.

Estimated taxes are another trap. NIIT is included in the pay-as-you-go tax system, and a large gain or year-end Opportunity Fund inclusion may require additional withholding or estimated payments. The IRS can assess an underpayment penalty even if the return is fully paid in April. Withholding later in the year can sometimes receive more favorable timing treatment than a late estimated payment, but the correct approach depends on the household’s safe-harbor calculation and cash flow.¹²

The last trap is allowing the tax to drive the investment decision. Holding an oversized position solely to avoid 3.8%, accepting a weak buyer note solely to spread gain, or moving into lower-yielding assets without comparing after-tax return can create a larger economic cost than the tax saved. We are tax-aware, not tax-driven. The goal is to reduce avoidable tax while preserving diversification, liquidity, risk control, and the family’s actual objectives.

The takeaway is straightforward: NIIT planning begins before the transaction and before December. We need an updated income projection, a clean estimate of net investment income, the tax basis of assets that may be sold, and a calendar of conversions, distributions, charitable gifts, business payments, and trust distributions. Once those pieces are visible together, the 3.8% surtax becomes a planning variable rather than a year-end surprise.

This is the framework; the specifics are a conversation with us, your CPA, and, where trusts or transactions are involved, your attorney. Our team will continue monitoring 2026 guidance and coordinating the investment plan with the tax plan so that each decision is evaluated on a multi-year, after-tax basis.

All my best,

Brandon VanLandingham, CFA, CMT, CFP

Founder / CIO

[1] U.S. House of Representatives, Office of the Law Revision Counsel, 26 U.S.C. Section 1411—Imposition of Tax (text in effect July 8, 2026), https://uscode.house.gov/view.xhtml?req=%28title%3A26+section%3A1411+edition%3Aprelim%29.

[2] Internal Revenue Service, Questions and Answers on the Net Investment Income Tax and Net Investment Income Tax (thresholds, MAGI, included and excluded income, residence gain, examples, and interaction with Additional Medicare Tax; current IRS pages accessed July 16, 2026), https://www.irs.gov/newsroom/questions-and-answers-on-the-net-investment-income-tax and https://www.irs.gov/individuals/net-investment-income-tax.

[3] Internal Revenue Service, Revenue Procedure 2025-32, Section 4.01, Table 5, published in Internal Revenue Bulletin 2025-45 (2026 estate and trust brackets; top 37% bracket begins above $16,000), https://www.irs.gov/irb/2025-45_IRB.

[4] Internal Revenue Service, Instructions for Form 8960 (2025), Net Investment Income Tax—Individuals, Estates, and Trusts (most recent final instructions available as of July 16, 2026; deductions, passive activities, dispositions, and deferred-sale adjustments), https://www.irs.gov/instructions/i8960.

[5] Internal Revenue Service, Publication 537 (2025), Installment Sales and Like-Kind Exchanges—Real Estate Tax Tips (installment eligibility, depreciation recapture, and Section 1031 rules), https://www.irs.gov/publications/p537 and https://www.irs.gov/businesses/small-businesses-self-employed/like-kind-exchanges-real-estate-tax-tips.

[6] Internal Revenue Service, Notice 2026-40, Transitional Guidance on Qualified Opportunity Zones and Invest in a Qualified Opportunity Fund (pre-2027 deferred-gain inclusion and later-law transition), https://www.irs.gov/pub/irs-drop/n-26-40.pdf and https://www.irs.gov/credits-deductions/businesses/invest-in-a-qualified-opportunity-fund.

[7] Internal Revenue Service, Publication 526 (2025), Charitable Contributions and Publication 505 (2026), Tax Withholding and Estimated Tax (capital-gain property rules and 2026 charitable-deduction floor), https://www.irs.gov/publications/p526 and https://www.irs.gov/publications/p505.

[8] Internal Revenue Service, Publication 550 (2025), Investment Income and Expenses (capital-loss offsets, $3,000 annual deduction limit, and carryforwards), https://www.irs.gov/publications/p550.

[9] Internal Revenue Service, 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500, November 13, 2025, and Retirement Topics—Catch-Up Contributions (2026 Roth catch-up rule), https://www.irs.gov/newsroom/401k-limit-increases-to-24500-for-2026-ira-limit-increases-to-7500 and https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-catch-up-contributions.

[10] Internal Revenue Service, Revenue Procedure 2025-19, published in Internal Revenue Bulletin 2025-21 (2026 HSA contribution limits), https://www.irs.gov/irb/2025-21_IRB.

[11] Internal Revenue Service, Publication 590-B (2025), Distributions from Individual Retirement Arrangements, 2026 QCD worksheet and instructions (2026 maximum of $111,000), https://www.irs.gov/pub/irs-pdf/p590b.pdf.

[12] Internal Revenue Service, Publication 505 (2026), Tax Withholding and Estimated Tax, https://www.irs.gov/publications/p505.

This piece is educational. It is not legal, tax, or accounting advice and is not a recommendation to take or refrain from any specific action. Tax law is fact-specific and changes regularly. Please coordinate any decisions discussed here with your attorney, your CPA, and Perissos before acting.

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