How Do You Report the NIIT on Form 8960? (w/Examples) + FAQs

Quick Answer: You report the Net Investment Income Tax (NIIT) on Form 8960 by adding up your investment income (Part I), subtracting allocable deductions (Part II), then multiplying the smaller of your net investment income or your MAGI over the threshold by 3.8% (Part III). You attach Form 8960 to your Form 1040 for tax year 2025.

The NIIT is a 3.8% surtax on investment income that hits once your modified adjusted gross income (MAGI) crosses a fixed line — $200,000 if you are single, $250,000 if you are married filing jointly, for tax year 2025. If you sold stock, collected dividends, earned rent, or cashed out a big gain this year, you may owe a tax most people never planned for, and the IRS expects it on the same return that is due April 15, 2026.

The hard part is not the 3.8% math. It is figuring out which dollars count as investment income, which expenses you can subtract, and how to handle tricky items like rental income, business income, and the sale of a partnership interest. Get those wrong and you either overpay or invite an IRS notice — and the Treasury Inspector General has repeatedly flagged the NIIT as one of the most under-reported taxes on individual returns.

This article reflects federal rules as of June 2026 and covers tax year 2025. The NIIT is a federal tax with no direct state equivalent. Tax law changes — confirm current figures before you file. This guide is educational and is not a substitute for advice from a licensed tax professional for your specific situation.

Here is what you will walk away knowing:

• 🧾 Exactly which line of Form 8960 each type of income and expense goes on.
• 💰 How to run the 3.8% calculation yourself, with real dollar examples you can copy.
• 🏠 When a home sale, rental, or business sale triggers the tax — and when it does not.
• ⚠️ The seven costliest mistakes that make filers overpay or get audited.
• 📅 The deadline, estimated-tax trap, and exactly what to do next.

What the NIIT Is and Who Owes It

The Net Investment Income Tax is a 3.8% surtax created by Section 1411 of the Internal Revenue Code, and it took effect on January 1, 2013. It is not part of your regular income tax brackets. It sits on top of them, and it only touches income that comes from your investments rather than your paycheck.

You owe the NIIT only if two things are true at the same time for tax year 2025. First, you must have net investment income (NII). Second, your MAGI must exceed the threshold for your filing status. The tax then applies to the smaller of those two numbers, which is the single most important rule on the entire form.

Because the tax targets the lesser of NII or your income over the threshold, a person with huge investment income but modest total income may owe little or nothing. The IRS reminds taxpayers that these threshold amounts are not indexed for inflation, so more households drift into the tax every year as wages and portfolios grow.

The 2025 MAGI thresholds by filing status are fixed dollar amounts, not adjusted figures.

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

MAGI for NIIT purposes is your regular adjusted gross income increased by certain foreign earned income excluded under Section 911. For most U.S. filers with no foreign income, MAGI simply equals the AGI shown on their Form 1040. Nonresident aliens are not subject to the NIIT at all.

Which Income Counts (and Which Does Not)

Net investment income is the heart of Form 8960, and the difference between what counts and what does not is where filers lose the most money. Knowing the categories before you start the form keeps you from taxing income that is legally exempt.

Income That Counts as NII

Net investment income generally includes interest, dividends, capital gains, rental and royalty income, non-qualified annuities, and income from a business that is a passive activity to you. It also includes income from a business that trades in financial instruments or commodities. In plain terms, money your money earns while you sit back is usually NII.

Capital gains are the most common trigger. Gains from selling stocks, bonds, and mutual funds count, as do capital gain distributions from funds and gain on selling investment real estate or a second home. The consequence of forgetting these is an inaccurate return, because the IRS already receives this data on Forms 1099, and a mismatch invites a CP2000 notice and interest.

Income That Does Not Count

Several large income categories are excluded from NII even when they push your MAGI up. Wages, self-employment income, Social Security benefits, unemployment, alimony, tax-exempt interest, and distributions from qualified retirement plans such as 401(k)s, 403(b)s, traditional IRAs, and Roth IRAs are all outside the tax. Operating income from a business in which you materially participate is also excluded.

This split creates a strange but real outcome. A retiree pulling $300,000 from a traditional IRA has high MAGI but may owe zero NIIT, because IRA distributions are not investment income — though that distribution does raise MAGI and can push other investment income over the threshold. The common misconception is that “high income equals NIIT,” when in fact you need investment income in the mix. What you should do is sort every income source into “counts” or “does not count” before touching the form, so you neither overpay nor miss a category.

Form 8960, Part by Part

Form 8960 has three short parts: investment income, deductions and modifications, and the tax computation. You attach it to your Form 1040 and pay any NIIT with that return. Below is each line, what goes on it, and the consequence of getting it wrong.

Part I — Investment Income (Lines 1–8)

Part I gathers every dollar of gross investment income before any expenses. Each line pulls directly from a specific line on your Form 1040, so accuracy here is mostly transcription plus a few adjustments.

• Line 1 — Taxable interest: Enter taxable interest from Form 1040, line 2b. Interest earned in your non-passive trade or business is later removed on line 7.
• Line 2 — Ordinary dividends: Enter ordinary dividends from Form 1040, line 3b. ESOP dividends and Alaska Permanent Fund Dividends are backed out on line 7.
• Line 3 — Annuities: Enter taxable amounts from non-qualified annuities only; annuities from 401(k), 403(b), IRA, and 457(b) plans are excluded.
• Line 4a — Rental, royalty, partnership, S corp, trust income: Enter the total from Schedule 1 that flows from Schedule E, Schedule C, and Schedule F.
• Line 4b — Adjustment for non-passive business income: Subtract income from a non-passive trade or business that does not belong in NII (for example, active business income).
• Line 4c — Combined: Add lines 4a and 4b.
• Line 5a — Net gain or loss from dispositions: Enter net gain from Schedule D and Form 4797 that is included in your income.
• Line 5b — Net gain adjustment: Remove gain from property held in a non-passive business and excluded principal-residence gain.
• Line 5c — Disposition of partnership/S corp interest adjustment: Adjust gain or loss when you materially participated and sold an interest.
• Line 5d — Combined net gain: Add lines 5a, 5b, and 5c.
• Line 6 — CFC and PFIC adjustments: Adjust for income from controlled foreign corporations and passive foreign investment companies.
• Line 7 — Other modifications: Make any remaining adjustments, such as removing self-charged interest from a non-passive entity.
• Line 8 — Total investment income: Add lines 1, 2, 3, 4c, 5d, 6, and 7.

The consequence of misplacing income here is direct: every extra dollar on line 8 can be taxed at 3.8%, and every dollar you wrongly omit is a potential underpayment. The most common error is entering active business income on line 4a without backing it out on line 4b, which inflates the tax. What you should do is reconcile each line back to its source schedule before moving on.

Part II — Investment Expenses and Modifications (Lines 9–10)

Part II lets you subtract the deductions that are properly allocable to your investment income, which lowers the taxable base. This is the part most filers skip, and skipping it means overpaying.

• Line 9a — Investment interest expense: Enter interest paid to carry investments, generally from Form 4952.
• Line 9b — State, local, and foreign income tax: Enter the portion of state income tax allocable to investment income.
• Line 9c — Miscellaneous investment expenses: Enter other allocable costs, such as certain fiduciary fees for estates and trusts.
• Line 10 — Total deductions and modifications: Add lines 9a, 9b, and 9c.

Deductible items include investment interest, advisory and brokerage fees, rental expenses, tax-preparation fees allocable to investments, and the portion of state income tax tied to investment income. The consequence of ignoring line 9b is real money — a filer with $20,000 of state tax allocable to investments who skips it overpays by as much as $760. What you should do is allocate state income tax in proportion to investment income versus total income and keep your worksheet.

Part III — Tax Computation (Lines 12–17)

Part III runs the final math that produces your NIIT. This is where the “lesser of” rule is applied mechanically.

• Line 12 — Net investment income: Subtract line 10 from line 8.
• Line 13 — MAGI: Enter your modified adjusted gross income.
• Line 14 — Threshold: Enter the threshold for your filing status ($250,000 MFJ, $200,000 single/HOH, $125,000 MFS for 2025).
• Line 15 — Excess MAGI: Subtract line 14 from line 13; if zero or less, you owe no NIIT.
• Line 16 — Smaller of line 12 or line 15: This is your taxable base.
• Line 17 — NIIT: Multiply line 16 by 3.8% (0.038) and carry it to Schedule 2 of Form 1040.

The whole form exists to produce line 16, the smaller of your NII or your excess MAGI. Multiply that by 0.038 and you have your tax. Estates and trusts use the separate Part on lines 18a–21 instead, which we cover below.

Worked Numeric Examples

Numbers make the form click, so here are full calculations you can copy line for line. Each uses tax year 2025 figures.

Example 1: Single Filer With Dividends and Gains

Maria is single. She earns $180,000 in wages, plus $30,000 of dividends and $20,000 of net capital gains. Her MAGI is $230,000.

• Net investment income (line 12): $30,000 + $20,000 = $50,000
• Excess MAGI over $200,000 (line 15): $230,000 − $200,000 = $30,000
• Smaller of the two (line 16): $30,000
• NIIT (line 17): $30,000 × 3.8% = $1,140

Maria owes $1,140 even though her investment income was $50,000, because the tax applies to the lesser number. Had her wages been lower, her tax would shrink too.

Example 2: Married Couple With a Big Home Sale

This mirrors an official IRS example. Ben and Carla file jointly and sell their long-time home for a $600,000 gain. The Section 121 exclusion removes $500,000, leaving $100,000 of taxable gain. They have $125,000 of other NII, so total NII is $225,000. Their MAGI is $300,000.

• Net investment income (line 12): $225,000
• Excess MAGI over $250,000 (line 15): $300,000 − $250,000 = $50,000
• Smaller of the two (line 16): $50,000
• NIIT (line 17): $50,000 × 3.8% = $1,900

The $500,000 of excluded home-sale gain never touches the NIIT, because gain excluded for regular tax is also excluded here.

Example 3: Passive Business Owner

Dev is single with $180,000 of wages and $90,000 from a passive partnership interest, matching another IRS scenario. His MAGI is $270,000.

• Net investment income (line 12): $90,000
• Excess MAGI over $200,000 (line 15): $270,000 − $200,000 = $70,000
• Smaller of the two (line 16): $70,000
• NIIT (line 17): $70,000 × 3.8% = $2,660

Because Dev is passive in the partnership, the $90,000 counts as NII. If he had materially participated, that income would be excluded and his NIIT would be far lower.

Which Situation Applies to You?

The right path through Form 8960 depends on who you are and what triggered the tax. Use this to find your branch.

• You only have portfolio income (interest, dividends, fund gains): Your form is simple — Part I lines 1, 2, and 5a, then straight to Part III.
• You own rental real estate: Watch the passive rules; rental income is usually NII unless you are a qualifying real estate professional under the safe harbor.
• You own a pass-through business: Material participation is everything — active income is excluded, passive income is taxed. Use line 4b to back out active income.
• You sold a partnership interest or S corp stock: You likely need a line 5c adjustment and an attached statement.
• You are an estate or trust (Form 1041): You use lines 18a–21 and a much lower threshold of $15,650 for 2025.
• You sold a personal home: Only gain above the Section 121 exclusion ($250,000 single / $500,000 joint) can be NII.

Estates and Trusts: The Separate Path

Estates and trusts owe the NIIT too, but the rules are harsher because the threshold is so low. For 2025, a trust or estate owes the tax on the lesser of its undistributed net investment income or the amount its AGI exceeds $15,650 — the dollar figure where the top trust tax bracket begins.

These filers complete Form 8960 lines 18a through 21 instead of the individual computation. Line 18a is undistributed NII, line 19 figures AGI over the threshold, line 20 takes the smaller amount, and line 21 multiplies by 3.8%. Distributing income to beneficiaries before year-end is the classic planning move, because distributed income is taxed to the beneficiary, not trapped in the trust at the low threshold.

Some trusts are exempt entirely, including grantor trusts, charitable trusts, qualified retirement plan trusts, charitable remainder trusts, and real estate investment trusts. The consequence of missing the $15,650 threshold is severe relative to individuals — a trust with just $20,000 of retained investment income can owe NIIT, so executors and trustees should plan distributions carefully and consider an estate attorney for complex estates.

Mistakes to Avoid

These errors cost real dollars or invite IRS notices. Each is common and each is preventable.

• Forgetting the “lesser of” rule: Taxing all your NII instead of the smaller figure overstates the tax, sometimes by thousands.
• Including IRA or 401(k) distributions as NII: These are excluded; counting them inflates your tax even though they do raise MAGI.
• Skipping Part II deductions: Leaving off investment interest, advisory fees, and allocable state tax means overpaying the 3.8%.
• Treating active business income as passive: Income from a business you materially run is excluded; reporting it on line 4a without a line 4b adjustment overtaxes you.
• Taxing excluded home-sale gain: Gain inside the Section 121 exclusion is never NII; including it is a costly error.
• Ignoring the partnership-sale adjustment: Failing to compute the line 5c adjustment and attach the required statement can misstate gain and trigger IRS contact.
• Skipping estimated payments: The NIIT is subject to estimated tax rules, so a year-end surprise can mean an underpayment penalty on top of the tax.

Do’s and Don’ts

• Do sort every income source into NII and non-NII before starting the form, so the math is clean. Why: it prevents the most common overpayment errors.
• Do allocate state income tax and advisory fees to investment income on Part II. Why: these deductions directly cut your 3.8% tax.
• Do check material participation for every business and rental. Why: it decides whether income is excluded or taxed.
• Do keep records for the entire life of each investment. Why: the IRS requires basis records for carrybacks and carryforwards.
• Do adjust withholding or estimated payments if you expect NIIT. Why: it avoids underpayment penalties.
• Don’t assume high income alone triggers the tax. Why: you need actual investment income for any NIIT to apply.
• Don’t include tax-exempt municipal bond interest. Why: it is excluded and adding it overpays.
• Don’t forget nonresident aliens are exempt. Why: a U.S. spouse may file separately for NIIT and avoid the tax.
• Don’t use a foreign tax credit to cut NIIT. Why: that credit only offsets regular income tax, not the NIIT.
• Don’t file without Form 8960 if MAGI exceeds the threshold and you have NII. Why: omitting it understates tax and risks penalties.

Pros and Cons of Planning Around the NIIT

• Pro — Tax-deferred accounts help: Income inside IRAs and 401(k)s is not NII, so shifting investments there can lower the tax base. Why: it removes income from the calculation entirely.
• Pro — Material participation can exempt business income: Becoming active in a business removes that income from NII. Why: active income is outside Section 1411.
• Pro — Timing gains matters: Spreading capital gains across years can keep MAGI under the threshold. Why: the tax only applies above the line.
• Pro — Deductions are available: Allocable expenses reduce NII directly. Why: fewer taxed dollars means less 3.8% tax.
• Pro — Municipal bonds avoid it: Tax-exempt interest is not NII. Why: it never enters the calculation.
• Con — Thresholds are not indexed: Fixed thresholds pull more people in each year. Why: inflation raises income but not the limit.
• Con — Trust threshold is very low: Estates and trusts hit the tax at just $15,650. Why: it tracks the top trust bracket.
• Con — It stacks on capital gains tax: The 3.8% sits on top of your 15% or 20% capital gains rate. Why: it is a separate surtax.
• Con — Planning can be complex: Material participation and grouping rules are technical. Why: they require careful records and sometimes a CPA.
• Con — Estimated-tax exposure: Owing it can create penalties if you do not pre-pay. Why: it is part of the estimated tax system.

Deadlines, Costs, and Timing

You report and pay the NIIT with your Form 1040, due April 15, 2026 for tax year 2025, or October 15, 2026 with an extension to file (though tax owed is still due in April). The NIIT is part of the estimated tax system, so if you expect to owe it, raise your quarterly payments or withholding to dodge a penalty.

Cost depends on complexity. A simple Form 8960 with only dividends and gains is something most DIY software handles for the price of the software. A return with passive activity grouping, a partnership sale, or trust distributions can run several hundred to over a thousand dollars at a CPA — and that help is worth it once line 5c adjustments or material-participation tests enter the picture.

What to Do Next

Take these steps in order to file correctly and on time.

1. Pull your Form 1040 income lines and your investment statements (1099-INT, 1099-DIV, 1099-B, Schedule E).
2. Sort every income source into NII versus non-NII using the lists above.
3. Gather your deductible investment expenses and your allocable state income tax for Part II.
4. Complete Form 8960 Parts I, II, and III, then carry line 17 to Schedule 2 of Form 1040.
5. Confirm whether you needed estimated payments and adjust for next year to avoid penalties.
6. If you sold a business interest, own rentals with grouping questions, or administer a trust, call a CPA or tax attorney before filing.

For deeper dives, see a companion guide on filling out Schedule D and Form 8949 for capital gains, and review the IRS page on estimated taxes so the NIIT never becomes an April surprise.

FAQs

What is the NIIT rate for 2025?

3.8%. The Net Investment Income Tax is a flat 3.8% surtax on the lesser of your net investment income or the amount your MAGI exceeds your filing-status threshold for tax year 2025.

Who has to file Form 8960?

Anyone with net investment income whose MAGI exceeds the threshold. For 2025 that means MAGI over $200,000 (single/HOH), $250,000 (MFJ), or $125,000 (MFS). You attach Form 8960 to your Form 1040.

Does the NIIT apply to the sale of my home?

No, not the excluded portion. Gain shielded by the Section 121 exclusion — $250,000 single or $500,000 joint — is exempt. Only gain above that exclusion can count as net investment income.

Are 401(k) and IRA withdrawals subject to the NIIT?

No. Distributions from qualified plans like 401(k)s, 403(b)s, traditional IRAs, and Roth IRAs are excluded from net investment income, though they do raise your MAGI and can push other investment income over the threshold.

Is rental income subject to the NIIT?

Usually yes. Rental income is generally net investment income unless you qualify as a real estate professional and meet the safe harbor showing the rental rises to a trade or business in which you materially participate.

Does the NIIT apply to capital gains?

Yes. Gains from stocks, bonds, mutual funds, fund distributions, and investment real estate are net investment income, to the extent not offset by capital losses, when your MAGI exceeds the threshold.

Are wages subject to the NIIT?

No. Wages, salaries, and self-employment income are excluded from net investment income. Self-employment income may instead face the separate 0.9% Additional Medicare Tax above certain thresholds.

What is the NIIT threshold for trusts in 2025?

$15,650. Estates and trusts owe the NIIT on the lesser of undistributed net investment income or AGI exceeding $15,650, the point where the top trust tax bracket begins for 2025.

Can tax credits reduce my NIIT?

Only chapter-1 credits. Credits allowed against regular income tax can offset NIIT, but credits limited to chapter 1 — like the foreign tax credit and general business credit — cannot reduce your NIIT liability.

Do nonresident aliens pay the NIIT?

No. Nonresident aliens are not subject to the NIIT. A U.S. citizen married to a nonresident alien generally uses the married-filing-separately threshold of $125,000 unless a joint election is made.

Is the NIIT the same as the Additional Medicare Tax?

No. The 3.8% NIIT applies to investment income, while the 0.9% Additional Medicare Tax applies to wages and self-employment income. You can owe both, but never on the same dollars.

Do I have to make estimated payments for the NIIT?

Yes, if you expect to owe it. The NIIT is subject to the estimated tax rules, so adjust your withholding or quarterly payments to avoid an underpayment penalty when you file.