2026 NIIT Planning: Reduce the 3.8% Surtax on Capital Gains, Rental Income, and Trusts

The Net Investment Income Tax is easy to miss because it does not work like the ordinary income tax or the long-term capital gain rate schedule. A taxpayer can be in a favorable capital gain bracket and still owe an extra 3.8% on investment income once modified adjusted gross income crosses the statutory threshold. For high earners, founders after a liquidity event, real estate investors, and families with nongrantor trusts, that extra layer can turn into five or six figures of tax.

As of June 23, 2026, the individual NIIT thresholds remain fixed at $200,000 for single and head-of-household filers, $250,000 for married filing jointly and qualifying surviving spouse filers, and $125,000 for married filing separately. Those thresholds are not the 2026 capital gain brackets. They are separate Form 8960 thresholds, and they create planning friction because nominal income, Roth conversions, bonuses, business exits, and portfolio gains can push more taxpayers into the surtax each year.

The Two-Part NIIT Test

NIIT is not imposed merely because a taxpayer has investment income. Form 8960 asks two questions: does the taxpayer have net investment income, and does modified adjusted gross income exceed the applicable threshold? If both are true, the tax applies to the lesser number.

That distinction drives the planning. A married couple with $260,000 of wages and $8,000 of dividends is over the joint MAGI threshold by $10,000, but NIIT applies only to the $8,000 of net investment income. A married couple with $900,000 of wages and $300,000 of capital gains is far above the threshold, so the limiting number is likely the net investment income itself. In the second case, reducing or deferring investment income directly reduces the 3.8% tax.

2026 Thresholds That Matter

The capital gain brackets are indexed for inflation, but the NIIT individual thresholds are statutory dollar amounts. For 2026, Rev. Proc. 2025-32 sets the top of the 15% long-term capital gain range at $613,700 for married joint filers and surviving spouses, $545,500 for single filers, and $579,600 for heads of household. Those taxable-income thresholds help determine whether a gain falls into the 0%, 15%, or 20% capital gain bracket.

NIIT uses MAGI thresholds instead. A taxpayer can be in the 15% long-term capital gain bracket and still owe 3.8% NIIT, producing an effective federal capital gain rate of 18.8% before state tax. A taxpayer in the 20% capital gain bracket can reach 23.8%. Planning should model both systems, plus state tax, estimated payments, and any pass-through entity tax election impact.

Income Items That Create the Surtax

Net investment income generally includes taxable interest, dividends, capital gains, nonqualified annuities, royalties, and passive rental or business income. It generally does not include wages, unemployment compensation, Social Security benefits, alimony, or most self-employment income. Retirement plan distributions and Roth conversions are not themselves net investment income, but they can increase MAGI and cause otherwise ordinary investment income to become exposed to NIIT.

The highest-risk transactions are usually concentrated: sale of a concentrated stock position, sale of a rental property, liquidation of a private fund interest, exercise and sale of equity compensation, installment sale collections, passive K-1 income, or a trust retaining income above the trust threshold. These items should be modeled before the transaction closes, not after Form 1099-B, Schedule K-1, or Form 1041 arrives.

Planning Moves Before Year-End

NIIT planning is not simply "avoid income." The right answer depends on whether the taxpayer is limited by MAGI excess or by net investment income. A practical year-end review should include:

• Harvest capital losses intentionally. Losses can reduce net capital gain and may reduce NII, but wash sale rules, portfolio exposure, and state conformity should be reviewed.
• Time capital gains around other income. Closing a sale in January rather than December can move the NIIT liability into a different tax year and improve estimated-tax cash flow.
• Donate appreciated securities instead of cash. When charitable intent already exists, donating appreciated stock can remove future gain from the return while preserving a charitable deduction subject to normal AGI limits.
• Model Roth conversions with Form 8960. Conversion income can push MAGI above the NIIT threshold even when the conversion itself is not NII.
• Review installment sale economics. Spreading gain can manage annual NII, but credit risk, interest, collateral, and depreciation recapture can change the answer.

Real Estate and Pass-Through Traps

Rental real estate requires more than a passive-loss analysis. Form 8960 instructions state that rental income can still be included in NII if the income is not derived in the ordinary course of a section 162 trade or business. Real estate professional status under section 469(c)(7) helps only when the taxpayer materially participates and the rental activity meets the trade-or-business standard or another applicable NIIT rule.

The same issue appears with partnership and S corporation exits. A sale of a partnership interest or S corporation stock is generally included in NII, but materially participating owners may need a separate adjustment analysis. Installment sales can also require NIIT adjustments in the year of sale and later collection years. Owners should not assume that a K-1 activity labeled "nonpassive" automatically removes all gain from Form 8960.

Trust and Estate Exposure

Nongrantor trusts can hit NIIT quickly because the trust threshold is tied to the point where the highest estate and trust income tax bracket begins. For 2026, Rev. Proc. 2025-32 places the top estate and trust ordinary income bracket above $16,000. That is a very low threshold compared with individual NIIT thresholds.

Trustees should coordinate fiduciary accounting income, distributable net income, beneficiary tax profiles, and the trust instrument before year-end distributions are made. Distributing income may shift tax to beneficiaries with lower marginal rates or unused NIIT capacity, but it can also affect asset protection, family governance, state fiduciary income tax, and the economics of retaining capital for future beneficiaries.

Common Mistakes

• Using taxable income instead of MAGI. Capital gain brackets and NIIT thresholds measure different things.
• Ignoring Roth conversion spillover. The conversion may not be NII, but it can expose dividends, gains, and passive income to NIIT.
• Assuming all real estate professional income is exempt. The NIIT analysis still requires material participation and trade-or-business support.
• Forgetting trusts. A nongrantor trust can owe NIIT at income levels that would be immaterial for an individual taxpayer.
• Missing estimated-tax cash flow. NIIT is reported on Form 8960 and flows to the income tax return; underpayment penalties can apply when withholding or estimates are not adjusted.
• Planning only at the federal level. State capital gain, state trust tax, residency, and pass-through tax elections can dominate the final after-tax result.

The Bottom Line

NIIT planning belongs in the same model as capital gains, Roth conversions, passive activity rules, trust distributions, and state tax. The taxpayers most exposed in 2026 are not necessarily the taxpayers with the highest ordinary income. They are the taxpayers with concentrated investment income, retained trust income, passive rental income, or transaction timing that pushes MAGI over a fixed threshold. Build the Form 8960 projection before the gain is locked in.