Net Investment Income Tax (NIIT) and Real Estate Professionals

The tax reaches rents and gains unless they come from a nonpassive trade or business

Section 1411 imposes 3.8% on the lesser of net investment income or modified AGI above $250,000 for joint filers, $200,000 for single filers and $125,000 for married filing separately. Net investment income includes rents and gain on property, except income derived in the ordinary course of a trade or business and gain on property held in one, and section 1411(c)(2) puts passive activities back in.

The Form 8960 instructions add that the trade-or-business test is section 162, which is narrower than the passive activity rules. Escaping the tax therefore takes two things at once: the rental must be a section 162 business, and it must be nonpassive for you.

Real estate professional status is necessary but not sufficient

Rental activity is passive by default. Section 469(c)(7) lifts that default for a taxpayer who performs more than half of their personal services, and more than 750 hours, in real property trades or businesses in which they materially participate; on a joint return one spouse must meet both tests alone. Even then, each rental is nonpassive only if you materially participate in it. The tests are covered in real estate professional status.

The Form 8960 instructions say plainly that qualifying as a real estate professional does not necessarily mean the rental is a trade or business. If it is not a section 162 business, or you do not materially participate, the rental income is included in net investment income even though it is nonpassive for loss purposes. A single triple-net leased building with little activity is the common example of the gap.

The 500-hour safe harbor settles both questions for active professionals

Reg. section 1.1411-4(g)(7) gives a safe harbor to a real estate professional who participates in a rental real estate activity for more than 500 hours during the year, or for more than 500 hours in any five of the ten preceding years. The rents are then deemed derived in the ordinary course of a trade or business, and gain on property used in that activity is deemed gain on property held in a trade or business, so both fall outside the tax.

Participation counts the same way as for material participation. An owner with the election under Reg. section 1.469-9(g) to treat all rental real estate as one activity applies the 500-hour test to the combined activity, which helps an owner of several buildings. Missing the safe harbor does not settle the matter; the regulation lets a professional show the income is excluded on the general rules.

Grouping and regrouping can change the result

The regulation also excludes rent from property rented to your own business that is recharacterized as nonpassive, and rent from a rental properly grouped with a trade or business in which you materially participate under Reg. section 1.469-4(d)(1). Gain on selling that property follows the same treatment.

Groupings are sticky. The Form 8960 instructions allow regrouping only when the original grouping was clearly inappropriate or has become so, or once under a fresh-start election in the first year you owe the tax, with disclosure under Rev. Proc. 2010-13. The grouping election covers the traps.

Worked example: a professional couple selling one of their buildings

Hypothetical, round figures. A married couple file jointly; one spouse works full time managing their apartment buildings and logs about 1,200 hours a year in the rental activity under the aggregation election. In 2026 their modified AGI is $900,000, including $300,000 of net rents and a $400,000 gain on selling one building.

Under the safe harbor, the rents and the gain are excluded from net investment income and the couple owe no 3.8% on them. Without it, and without showing a section 162 business, net investment income would be at least $700,000 against MAGI $650,000 over the threshold, so the tax would be 3.8% of $650,000, or $24,700.

If the couple exchange the building, the deferred gain is outside net investment income either way, since the Form 8960 instructions exclude gain not recognized under section 1031. Run your own numbers with your CPA.

DST income is passive, so an exchange into a DST trades active income for investment income

In Rev. Rul. 2004-86, the property is net leased to a tenant who pays taxes, insurance and repairs, and the trustee's activities are limited to collecting and distributing income. The investors have no management role and no hours to count, so DST rent and a later sale gain are passive and are net investment income, whatever the investor's status elsewhere. DST passive losses and sale covers the loss side.

That is a trade-off, not a reason to avoid a traditional DST. A professional who exchanges into a DST defers the gain and its surtax, but the replacement income becomes subject to the 3.8% when modified AGI is above the threshold. NIIT on a rental sale and the 1031 shows the deferral side.