Net Investment Income Tax on Partnership Income: Active vs Passive Rules

The net investment income tax on partnership income turns on whether the partner materially participates in the partnership’s operations. A material participant in a partnership or S-corporation does not owe the 3.8% net investment income tax (NIIT) on their share of profits, even if income is investment income like rental real estate or business income. A passive partner—one who invests but does not actively manage—pays the tax on their share of ordinary business income, dividends, and capital gains, subject to income thresholds.

The 3.8% net investment income tax

In 2013, the IRS imposed a 3.8% tax on “net investment income” (NII) for high-income individuals and households. The tax applies to:

• Ordinary business income (if passive)
• Capital gains
• Dividends (qualified and non-qualified)
• Interest income
• Rental income
• Royalties

Thresholds (adjusted annually for inflation):

• Single filers: $200,000 modified adjusted gross income (MAGI)
• Married filing jointly: $250,000 MAGI
• Married filing separately: $125,000 MAGI

If your MAGI exceeds the threshold, the lower of your net investment income or the excess MAGI is taxed at 3.8%. Example: a single filer with $220,000 MAGI and $50,000 NII pays 3.8% on $20,000 (the lower of $50,000 and $220,000 – $200,000).

Partnership income and material participation

For partnerships and S-corporations, the critical question is: did the partner materially participate in the business?

A partner who materially participates is treated as active in the business. Their share of ordinary business income is not net investment income, even if the partnership itself earns only investment-type income (e.g., rental real estate). This is a major distinction: a real estate partnership that collects rents could generate capital gains taxed as investment income, but a material participant avoids the 3.8% tax.

The seven-test framework for material participation

Section 469 establishes seven tests; a partner passes if they meet any one of them:

1. Active participation test: Participated in the activity for more than 100 hours during the year AND owned more than 10% of the activity.

2. Majority participation test: Participated for more than 500 hours AND that was more than any other individual.

3. Significant participation test: Participated for more than 100 hours AND the activity was “significant.” This applies when the person engaged in multiple significant activities; “significant” means more than 100 hours in at least three activities.

4. Prior participation test: Materially participated in at least three of the prior five tax years (for an activity that is not new).

5. Substantial participation test: Actively participated for at least 100 hours AND the partnership’s deductions did not exceed its income in any year (a tougher bar; rarely used).

6. Real estate professional test: Spent more than half of professional time in real estate operations AND more than 750 hours on real estate activities. A spouse can aggregate hours. This test is crucial for landlords and developers claiming active participation in rental real estate.

7. Business-stage test: If the activity is in its start-up phase (first 12 months) or development phase (before it begins generating revenue), participation of any amount is sufficient.

Example 1 (test 1): A partner in a real estate syndication worked 120 hours on acquisition, underwriting, and asset management in year one and held 15% of the partnership. Passes the 100-hour test and owns >10%. Material participant; their share of rental income is not NII; no 3.8% tax.

Example 2 (test 6): A realtor owns a rental property as a limited partner in a partnership with no involvement in day-to-day management. She spent 1,000 hours on her realtor business and 300 hours managing her rental property. If she qualifies as a real estate professional (>50% of professional time in real estate), she can aggregate the hours. 1,000 + 300 = 1,300 hours, of which 300 are real estate activities. This fails the “more than 750 hours in real estate activities” prong, so she does not qualify. The partnership income is passive; she owes 3.8% tax if above the MAGI threshold.

Rental real estate: special rules

Real estate receives favorable treatment under Section 469. Passive losses from rental real estate can offset active income (up to $25,000 annually, phasing out at higher AGI). But for NIIT purposes, the question remains: is the partner materially participating?

Individuals with substantial real estate involvement can claim material participation. Examples:

• A landlord who actively manages 15 rental properties, spending 120+ hours per year on repairs, leasing, and tenant issues, likely qualifies under test 1.
• A developer who spent 500+ hours on acquisition and construction of a project in year one passes test 2.
• A real estate professional (broker, appraiser, developer, construction manager) who spends 750+ hours in real estate and >50% of time in real estate qualifies under test 6.

For these individuals, their rental income avoids the 3.8% NIIT, even though it is capital gains and rental income.

Passive landlords (absentee investors, limited partners) do not qualify. Their rental income is passive; they owe 3.8% tax if MAGI exceeds the threshold.

Aggregation and grouping

Partnerships can be tricky when a partner has multiple investments. Hours in each activity are counted separately (unless aggregated). A person who spent 60 hours on Partnership A and 70 hours on Partnership B has not cleared the 100-hour bar for either, even though total hours are 130.

However, the IRS allows aggregation in certain cases:

• Real estate professional aggregation: Under test 6, a real estate professional can aggregate all real estate activities.
• Voluntary grouping: Partnerships can elect to group activities if they are part of an “appropriate economic unit.”

Most passive investors (limited partners in syndications, REITs) do not aggregate and remain passive.

Tax treatment of partnership distributions and capital gains

Partnership ordinary income (profit from operations) is taxed as ordinary income. Capital gains and dividend income passed through are taxed at their respective rates.

For NIIT purposes:

• A material participant’s share of partnership ordinary income is not NII (so no 3.8% tax).
• A material participant’s share of capital gains is NII (taxed at long-term or short-term rates, plus 3.8% if MAGI exceeds threshold).
• A passive investor’s share of ordinary income, capital gains, and dividends are all NII.

Example 3: A real estate syndication earned $2 million in rental income and realized $1 million in long-term gains from a sale. A material participant partner with a 5% stake received $100,000 in ordinary income and $50,000 in capital gains. The ordinary income is not NII (material participation). The capital gains are NII, so the partner owes tax on the $50,000 at the long-term capital gains rate plus 3.8% NIIT (if MAGI exceeds $200K). A passive investor in the same syndication owes NIIT on both the $100,000 and $50,000.

Burden of proof and documentation

Partners must document material participation. Hours logs, emails, calendar entries, invoices, and board minutes all support a claim. The IRS scrutinizes real estate professionals, particularly those claiming material participation while holding W-2 jobs. The burden is on the taxpayer to prove hours.

For the real estate professional test specifically:

• More than 50% of personal services during the year must be in real estate businesses.
• More than 750 hours must be spent on real estate activities.
• The individual must materially participate in the activity (usually test 1, 100+ hours, is sufficient once the 750 threshold is met).

A W-2 employee at an accounting firm cannot claim to be a real estate professional, even if they own rental properties, because their primary work is accounting, not real estate. A full-time real estate broker or developer can aggregate hours across properties.

Planning considerations

For investors in syndications: Passive investors typically have no choice—their share of profits triggers NIIT. The 3.8% is a cost of passive investment income.

For operators and sponsors: General partners who actively manage a partnership avoid NIIT on ordinary income, reducing their total tax burden. This is one reason why GPs command a share of profits beyond their capital contribution.

For landlords and developers: Material participation status is worth documenting carefully. A landlord who spends 150 hours per year on properties should track this via calendar, invoices, and correspondence to defend the material participation claim. Passive income is higher-taxed.

For real estate professionals: Properly documenting the 750-hour threshold and the 50%-of-time test is critical. A real estate appraiser who also owns rental properties must show that >50% of hours were in appraisal and that 750+ hours were in real estate activities broadly (appraisal + rental management).

See also