Does Passive K-1 Income Trigger the 3.8% NIIT? (w/Examples) + FAQs

This article reflects federal tax rules as of June 2026 and covers tax year 2025 (returns filed in 2026), with tax year 2026 figures noted where they differ. The Net Investment Income Tax is a federal tax only — no state piggybacks on it — but states tax the underlying income differently. Tax law changes, so confirm current figures before you file.

Quick Answer

Yes. Passive K-1 income generally triggers the 3.8% Net Investment Income Tax (NIIT). If you do not materially participate in the business that issued your Schedule K-1, that income counts as net investment income. You owe the tax only when your modified adjusted gross income tops $200,000 (single) or $250,000 (married filing jointly) for tax year 2025.

So if you are a silent partner, a limited partner in a fund, or an investor in a real estate syndication, the income on your K-1 is in the NIIT’s crosshairs. The danger is real: many investors learn about this tax only after a surprise bill arrives, because the K-1 itself does not always flag the income as “passive” in plain words, and the 3.8% hits on top of regular income tax.

Roughly 7 million tax returns reported some NIIT liability in a recent filing year, according to IRS Statistics of Income data, and the number climbs as more people invest through partnerships and LLCs. Here is what you will learn:

💰 The exact MAGI thresholds that switch the 3.8% tax on for tax year 2025 and 2026.
🔑 How “material participation” decides whether your K-1 income is passive or safe.
🧮 Three fully worked dollar examples so you can copy the math for your own return.
📋 A line-by-line look at Form 8960, the form that calculates the tax.
⚠️ The seven costly mistakes that cause surprise NIIT bills and IRS notices.

What the 3.8% NIIT Actually Is

The Net Investment Income Tax is a 3.8% federal surtax on investment income for higher earners. Congress created it under Internal Revenue Code Section 1411, and it took effect in 2013. It is sometimes called the “Medicare surtax” because the revenue helps fund Medicare, but it is not payroll tax and it is not Social Security tax.

The tax is not a flat 3.8% on all your investment income. You pay 3.8% on the smaller of two numbers: your net investment income, or the amount your modified adjusted gross income (MAGI) rises above your filing-status threshold. MAGI is usually the same as your regular adjusted gross income for most people, because the only add-back is certain foreign earned income, per IRS Topic 559.

Here is why this matters in real life. If you do not cross the income threshold, you owe zero NIIT, no matter how much passive K-1 income you have. The consequence of crossing it, though, is a sharp one: the threshold has no phase-in, so a single extra dollar of income can pull your investment income into the tax. A reader who plans a Roth conversion or sells a property near year-end can trip this wire without warning. The fix is to project your MAGI before December 31 and decide whether to defer income or harvest losses.

The 2025 tax law known as the One Big Beautiful Bill Act (OBBBA) did not change the 3.8% rate or the NIIT thresholds. A common misconception is that recent tax reform repealed or softened this surtax. It did not. The thresholds remain fixed and are not indexed for inflation, which means more taxpayers drift into NIIT range every year as incomes rise.

What Counts as a “K-1” and Why Passive Status Matters

A Schedule K-1 is the tax form a pass-through entity gives you to report your share of its income, deductions, and credits. Three kinds of entities issue K-1s: partnerships and multi-member LLCs (Form 1065), S corporations (Form 1120-S), and estates and trusts (Form 1041). The entity itself usually pays no income tax; instead, the income “passes through” to you and lands on your personal return.

The single most important question for NIIT is whether the K-1 income is passive or nonpassive. This split comes from Section 469, the passive activity rules. Passive income is income from a trade or business in which you do not materially participate, plus most rental income. Nonpassive (active) income comes from a business in which you do materially participate.

The consequence of this label is direct and expensive. Passive K-1 income from a trade or business is net investment income and is subject to the 3.8% NIIT once you cross the threshold. Nonpassive K-1 income from a business in which you materially participate is generally excluded from NIIT. So the same dollar of partnership income can be taxed or untaxed by the surtax based purely on how involved you are.

A frequent misconception is that the K-1 tells you outright whether income is passive. It often does not. The K-1 reports the numbers, but you determine material participation based on your hours and role. The smart move is to track your participation hours during the year and tell your tax preparer, because the preparer cannot guess your involvement from the form alone.

The Material Participation Test: The Real Trigger Switch

Material participation is the legal test that decides whether your K-1 trade-or-business income escapes the NIIT. The IRS lists seven tests in the Form 8582 rules and Publication 925. You only need to pass one of them for the year. If you pass even one, the activity is nonpassive and that income is generally safe from the 3.8% tax.

The Seven Tests in Plain English

You materially participate in a business if you meet any one of these for the tax year. The first is the most common, but any single one works, so check all seven before concluding income is passive. Missing a test you actually pass means paying 3.8% you did not owe.

You work more than 500 hours in the activity during the year.
Your participation is substantially all of the participation by everyone in the activity.
You work more than 100 hours and no one else works more than you do.
The activity is a “significant participation activity” (over 100 hours) and your total significant-participation hours across all such activities top 500.
You materially participated in the activity for any 5 of the last 10 years.
The activity is a personal service activity and you materially participated for any 3 prior years.
Based on all facts and circumstances, you participate on a regular, continuous, and substantial basis (and at least 100 hours).

Why Limited Partners Usually Lose This Test

Limited partners face an extra hurdle. Under the Section 469 regulations, a limited partner can usually only pass three of the seven tests — the 500-hour test, the 5-of-10-years test, or the 3-prior-years personal-service test. Because most limited partners are passive by design and do not work 500 hours, their K-1 income is almost always passive and therefore subject to NIIT. The lesson for an LP is simple: assume your income is passive and plan for the 3.8% unless you can document over 500 hours.

Rental Income Has Its Own Rule

Rental activity is treated as passive by default, even if you spend real time on it, under Section 469(c)(2). That means rental income on a K-1 is generally net investment income subject to NIIT. The main escape hatch is qualifying as a real estate professional under Section 469(c)(7) and materially participating, which can make the rental income nonpassive and pull it out of NIIT — but the Form 8960 instructions add that the rental must also rise to a Section 162 trade or business to be fully excluded.

Which Situation Applies to You?

The answer to “does my K-1 trigger NIIT?” depends on your role. Find your situation below and read the matching example later in the article.

You are a silent or limited partner (a fund, a syndication, a business you don’t run): your income is almost certainly passive and subject to NIIT once you cross the MAGI threshold.
You actively run the business and work over 500 hours: your income is likely nonpassive and excluded from NIIT, though you may owe self-employment tax instead.
Your K-1 reports rental income: it is passive by default and subject to NIIT, unless you are a qualifying real estate professional who materially participates.
Your K-1 reports interest, dividends, or royalties: these are investment income and subject to NIIT regardless of participation, unless earned in an active non-investment business.
Your MAGI is below $200,000 (single) or $250,000 (MFJ): you owe no NIIT this year, period — but watch year-end income spikes.

How the 3.8% Is Calculated: The Thresholds

The NIIT thresholds depend on your filing status and are not indexed for inflation, so they are the same for tax year 2025 and tax year 2026. The Form 8960 instructions confirm these amounts for individuals.

Filing Status	MAGI Threshold (Tax Years 2025 and 2026)
Married filing jointly or qualifying surviving spouse	$250,000
Single or head of household	$200,000
Married filing separately	$125,000

For estates and trusts, the threshold is far lower — it equals the dollar amount where the top trust tax bracket begins, which is $15,650 for tax year 2025 and $16,000 for tax year 2026, per the IRS Topic 559 guidance and Form 1041 instructions. This is why passive K-1 income held inside a non-grantor trust gets hit by NIIT so much faster than the same income held by an individual.

The math is always the same: multiply 3.8% by the lesser of your net investment income or your MAGI-over-threshold excess. The consequence of forgetting the “lesser of” rule is overpaying. A taxpayer with $300,000 MAGI (single) and $500,000 of passive income does not pay 3.8% on $500,000 — they pay it on the $100,000 of excess MAGI, which is the smaller number. To get this right, run both numbers and tax the smaller.

Worked Example: Passive K-1 Income Triggering NIIT

Let’s run the full math with real dollar figures so you can copy it.

Facts (tax year 2025): Maria is single. She has $185,000 in salary (wages are not investment income). She is a limited partner in a real estate syndication and her K-1 shows $60,000 of passive income. She has no other investment income.

Step 1 — Find MAGI. $185,000 wages + $60,000 passive K-1 = $245,000 MAGI.

Step 2 — Find net investment income. Her passive K-1 income of $60,000 is NII. Her wages are excluded.

Step 3 — Find MAGI over threshold. $245,000 − $200,000 (single) = $45,000 excess.

Step 4 — Tax the lesser. The lesser of $60,000 (NII) and $45,000 (excess) is $45,000.

Step 5 — Multiply by 3.8%. $45,000 × 0.038 = $1,710 of NIIT.

Maria owes $1,710 in NIIT on top of her regular income tax. Notice the tax is capped by her excess MAGI, not her full $60,000 of passive income — the “lesser of” rule saved her from a bigger bill.

Three Named Scenarios

Scenario 1 — The Silent Partner (Passive, Taxed)

What Happens	The NIIT Result
David invests $200,000 as a limited partner in a private equity fund and works zero hours.	His K-1 income is passive and counts fully as net investment income subject to the 3.8% tax.
His tax year 2025 MAGI is $400,000 (single), and his K-1 shows $50,000 of income.	He pays 3.8% on the lesser of $50,000 NII or $200,000 excess MAGI, so 3.8% × $50,000 = $1,900 NIIT.

David is the textbook passive investor. Because he does nothing operational, no material-participation test can save him, and the full $50,000 is investment income under Section 1411.

Scenario 2 — The Active S-Corp Owner (Nonpassive, Not Taxed)

What Happens	The NIIT Result
Priya owns 100% of an S corporation and works 2,000 hours a year running it.	She passes the 500-hour test, so her K-1 business income is nonpassive and excluded from NIIT.
Her tax year 2025 MAGI is $350,000, and her S-corp K-1 shows $220,000 of income.	She owes $0 NIIT on the business income, because it is active trade-or-business income, not investment income.

Priya’s involvement is her shield. The IRS notes that NIIT does not apply to income from an active business. Her S-corp reasonable wages are subject to payroll tax instead, but the surtax does not touch the active K-1 profit.

Scenario 3 — The Retiree Near the Cliff (Partly Taxed)

What Happens	The NIIT Result
Robert and Susan (married filing jointly) have $40,000 in pensions, $30,000 in dividends, and a $45,000 passive K-1 from a family LLC they don’t run.	Their dividends and passive K-1 are NII; pensions are excluded. Total NII = $75,000.
Their tax year 2025 MAGI is $280,000, which is $30,000 over the $250,000 MFJ threshold.	They pay 3.8% on the lesser of $75,000 NII or $30,000 excess = 3.8% × $30,000 = $1,140 NIIT.

Robert and Susan show the cliff effect. They are only $30,000 over the threshold, so the excess — not their full investment income — drives the bill. If they had kept MAGI at $250,000, they would owe nothing.

Walking Through Form 8960

You report and calculate the NIIT on Form 8960, which attaches to your Form 1040. You must file it if your MAGI tops your threshold. The form has three parts, and each line matters because an error here either overstates your tax or invites an IRS notice. Pair this with our guide on how to fill out Form 8960 for a line-by-line walkthrough.

Part I — Investment Income. Lines 1 through 4 gather interest, dividends, annuities, rents, royalties, and passive trade-or-business income. Passive K-1 income flows onto line 4a (income from Schedules C, E, and F). Line 4b is where you adjust out any nonpassive (active) income so it is not taxed.
Line 4b adjustment. This is the critical line for K-1 holders. If your K-1 income is nonpassive because you materially participate, you subtract it here. Forgetting this line is how active owners overpay the 3.8% tax.
Line 5a–5c — Net gains. Gains from selling a passive partnership interest go here. If you materially participated, line 5c adjusts the gain so the active portion is removed.
Part II — Investment Expenses. Lines 9 and 10 let you deduct expenses properly allocable to investment income, such as investment interest and state tax allocable to that income. Skipping allowed deductions means a higher NII and a bigger tax.
Part III — Tax Computation. Line 13 is your MAGI, line 14 is your threshold, and line 15 is the excess. Line 16 is your NII. Line 17 multiplies the lesser of the two by 3.8% — that is your NIIT, which carries to Schedule 2 of your 1040.

The deadline is your regular return deadline: April 15, 2026 for tax year 2025, or October 15, 2026 with an extension (though an extension to file is not an extension to pay). Missing the payment can trigger underpayment penalties, so adjust your estimated taxes or withholding during the year using the IRS Tax Withholding Estimator.

Federal vs. State: Does Your State Tax This Too?

The NIIT is purely a federal tax. No state imposes the 3.8% NIIT or conforms to Section 1411. So you will never see a separate “state NIIT” line. That said, your state almost certainly taxes the underlying passive K-1 income as ordinary income on your state return, just at the state’s own rate.

Concept	Federal	State
The 3.8% NIIT surtax	Applies under Section 1411	Does not exist at the state level
The passive K-1 income itself	Taxed as ordinary income	Generally taxed at the state’s income tax rate
No-income-tax states (e.g., Florida, Texas, Washington)	Federal NIIT still applies	No state tax on the income at all

A reader in Florida or Texas still owes the federal 3.8% on passive K-1 income, because living in a no-income-tax state does nothing for a federal surtax. A reader in California pays California income tax on the passive income plus the federal NIIT — but California adds no surtax of its own. The takeaway is to plan for the federal 3.8% no matter where you live.

Mistakes to Avoid

Assuming the K-1 labels income as passive. It often does not, and you must determine material participation yourself — guessing wrong means either overpaying or facing an IRS adjustment.
Forgetting the line 4b adjustment. Active owners who skip this subtraction on Form 8960 pay 3.8% on income that was never subject to NIIT.
Ignoring the year-end MAGI cliff. A late Roth conversion or asset sale can push you over the threshold and trigger the tax on income that was previously untaxed.
Treating all rental income as nonpassive. Rental income is passive by default and is subject to NIIT unless you are a qualifying real estate professional who materially participates.
Missing self-employment income overlap. Income already subject to self-employment tax is excluded from NIIT, so reporting it twice means overpaying.
Overlooking trust-level NIIT. A non-grantor trust hits the NIIT threshold at just $15,650 for tax year 2025, so passive K-1 income trapped in a trust is taxed far sooner.
Failing to make estimated payments. NIIT is not withheld from a K-1, so not adjusting estimated taxes can trigger an underpayment penalty in April.

Do’s and Don’ts

Do track your participation hours during the year, because over 500 hours can make K-1 income nonpassive and NIIT-free.
Do project your MAGI before December 31, since the threshold has no phase-in and a single dollar can trigger the tax.
Do harvest investment losses where appropriate, because losses reduce your net investment income.
Do coordinate with your tax preparer about each K-1’s passive status, as the form alone does not reveal your involvement.
Do raise your estimated tax payments, since the 3.8% is not withheld from K-1 distributions.
Don’t assume OBBBA repealed the NIIT — the 3.8% rate and thresholds are unchanged for 2025 and 2026.
Don’t treat a no-income-tax state as protection, because the NIIT is federal and applies everywhere.
Don’t forget the “lesser of” rule, or you may tax your full investment income instead of just the excess MAGI.
Don’t ignore suspended passive losses, which can offset passive income and lower your NII when freed up.
Don’t skip Form 8960 when your MAGI tops the threshold, because failing to file invites notices and penalties.

Pros and Cons of Active vs. Passive K-1 Treatment

There are trade-offs to being active versus passive, and the “best” answer depends on your goals.

Pro of being passive: less time and effort, since you simply invest and collect distributions.
Pro of being passive: passive losses can offset passive income, a flexibility active income lacks.
Pro of being active (nonpassive): your K-1 business income generally escapes the 3.8% NIIT.
Pro of being active: active losses are not trapped by the passive loss limitation rules.
Pro of being active: you control the business and its cash flow directly.
Con of being passive: your income is subject to the 3.8% NIIT once you cross the threshold.
Con of being passive: passive losses are limited and may be suspended until you have passive income.
Con of being active: active business income is often subject to self-employment tax, which can exceed the 3.8% you saved.
Con of being active: material participation demands real, documented hours every year.
Con of being active: the recordkeeping burden of proving over 500 hours can be heavy if audited.

When to Call a Professional

This article is educational and is not a substitute for advice from a licensed tax professional about your specific situation. Most straightforward W-2 plus single-K-1 returns can be handled with good software. But you should call a CPA or tax attorney when your situation gets complex: multiple K-1s with mixed passive and active income, the sale of a partnership interest, real estate professional status claims, grouping elections, or passive K-1 income flowing through a trust or estate. Professional help here typically costs a few hundred to a few thousand dollars, and it can easily pay for itself by correctly excluding active income or freeing suspended losses.

What to Do Next

Take these steps in order before you file.

Project your tax year 2025 MAGI now and compare it to your $200,000 / $250,000 / $125,000 threshold.
Pull every K-1 and identify which boxes are passive versus nonpassive based on your hours.
Gather your participation records — calendars, logs, emails — for any activity where you claim material participation.
Run the “lesser of” math using net investment income versus excess MAGI to estimate your 3.8% bill.
Adjust your fourth-quarter estimated tax payment (due January 15, 2026 for tax year 2025) to cover the NIIT.
Complete Form 8960 and attach it to your Form 1040 by April 15, 2026.
Call a professional if you have a partnership-interest sale, real estate professional claim, or trust-level income.

FAQs

Does passive K-1 income trigger the 3.8% NIIT?

Yes. Passive K-1 income from a trade or business in which you do not materially participate is net investment income and is subject to the 3.8% NIIT for tax year 2025, once your MAGI tops your filing-status threshold.

Is active K-1 income subject to NIIT?

No. If you materially participate in the business (for example, over 500 hours a year), the K-1 income is nonpassive and is generally excluded from the 3.8% NIIT, though it may face self-employment tax instead.

What are the NIIT income thresholds for 2025?

$200,000 for single filers, $250,000 for married filing jointly, and $125,000 for married filing separately. These amounts are not indexed for inflation and are identical for tax year 2026.

How much is the Net Investment Income Tax?

3.8%. You pay it on the lesser of your net investment income or the amount your MAGI exceeds your threshold, not on your total investment income.

Does rental K-1 income count for NIIT?

Yes. Rental income is passive by default under Section 469 and is subject to NIIT, unless you are a qualifying real estate professional who materially participates and the activity is a Section 162 trade or business.

Did the 2025 tax law (OBBBA) change the NIIT?

No. OBBBA left the 3.8% rate and all NIIT thresholds unchanged for tax years 2025 and 2026, despite a common belief that recent tax reform repealed the surtax.

Do any states impose their own version of the NIIT?

No. The NIIT is a purely federal tax under Section 1411, and no state conforms to it, though states tax the underlying K-1 income at their own ordinary rates.

What form reports the 3.8% NIIT?

Form 8960. You attach it to your Form 1040, and the resulting tax carries to Schedule 2; you must file it whenever your MAGI exceeds your threshold.

Is K-1 income from selling my partnership interest subject to NIIT?

Yes, generally. Gain from selling a partnership interest or S-corp stock is net investment income, though Form 8960 line 5c lets you adjust out the portion tied to a business in which you materially participated.

Why is passive K-1 income inside a trust taxed faster?

The trust threshold is far lower. A non-grantor trust hits NIIT at just $15,650 of AGI for tax year 2025 ($16,000 for 2026), versus $200,000 or more for individuals.

Does the NIIT apply to my IRA or 401(k) K-1 income?

No. Income inside a qualified retirement account is not your net investment income, and distributions from those accounts are specifically excluded from NIIT.

Can passive losses reduce my NIIT?

Yes. Allowed passive losses and suspended losses freed up in the current year can offset passive income, lowering your net investment income and the 3.8% tax you owe.

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