# NIIT Explained: Who Owes the 3.8% Surtax and How to Cut It

URL: https://elevatedtaxstrategies.com/tax-planning/net-investment-income-tax-explained/
Markdown: https://elevatedtaxstrategies.com/tax-planning/net-investment-income-tax-explained.md
Category: Tax Planning
Published: 2026-10-16
Author: Ramon Liriano Jr.

> The net investment income tax is a 3.8% surtax above a fixed income line. See who owes it, the lesser-of formula, and legal ways to reduce it.

## TLDR

The **net investment income tax (NIIT)** is a flat **3.8%** surtax on investment income, on top of your regular tax. It kicks in once your **modified adjusted gross income (MAGI)** crosses **$200,000** (single or head of household), **$250,000** (married filing jointly), or **$125,000** (married filing separately). These numbers are set by law and **have never been adjusted for inflation**, so more people owe this tax every year even though the rule itself has not changed. The tax applies to the **smaller** of your net investment income or the amount your MAGI sits above the threshold, never to your full income.

You check your tax return and see a line you do not remember from last year: an extra 3.8% tax, buried on a form called 8960. Your tax preparer mentions "NIIT" like you should already know what it is.

You do not owe this because you did something wrong. You owe it because your income crossed a line that Congress drew in 2013 and never moved again. Wages do not trigger it directly. Interest, dividends, capital gains, and rental income do.

The frustrating part is that the math feels arbitrary until you see it laid out. Once you see the **lesser-of rule**, the tax stops being mysterious and starts being something you can plan around.

In this guide, you'll learn:

- See the exact MAGI thresholds that trigger the 3.8% tax, and why they never move
- Understand the "lesser-of" formula that caps how much of your income actually gets taxed
- Learn what counts as net investment income (and the big categories that don't)
- See a full worked example from gross income to the final NIIT bill
- Get the legal moves that actually reduce or avoid this tax

## What the net investment income tax is

The NIIT is a federal surtax created by the Health Care and Education Reconciliation Act of 2010, the companion legislation to the Affordable Care Act. It took effect on **January 1, 2013** and is codified at **Internal Revenue Code Section 1411**.

The rate is a flat **3.8%**. It applies to individuals, estates, and certain trusts whose income from investments crosses a MAGI threshold.

The thresholds below are dollar amounts written directly into the Code (Section 1411(b)). They are not adjusted for cost-of-living changes the way tax brackets or the standard deduction are. That is unusual, and it is the single most important thing to understand about this tax.

### The MAGI thresholds

**NIIT MAGI thresholds, statutory and not indexed**

|  | Filing status | MAGI threshold |
| --- | --- | --- |
| Single or head of household | $200,000 |
| Married filing jointly | $250,000 |
| Married filing separately | $125,000 |

For most people, **MAGI is the same as regular AGI**, found near the bottom of the front page of your Form 1040. A small number of taxpayers with certain foreign income exclusions add those amounts back in to get MAGI, but that affects a narrow slice of filers.

> **Note: These numbers have not changed since 2013**
>
> The $200,000 single threshold and $250,000 joint threshold were set by statute in the original law and have **never been adjusted for inflation**. A couple earning $250,000 in 2013 dollars was genuinely high-income. A couple earning $250,000 today, after more than a decade of wage growth, is upper-middle-income in a lot of metro areas. The tax reaches further every year without Congress lifting a finger.

## The lesser-of rule: how the tax is actually figured

This is the part that confuses people the most. The 3.8% does **not** apply to your whole MAGI, and it does not apply to your whole net investment income either.

It applies to the **smaller** of these two numbers:

1. Your **net investment income** for the year, or
2. The amount your **MAGI exceeds the threshold** for your filing status

Whichever number is smaller is the one that gets taxed at 3.8%.

### Why the "smaller of" matters

Say you are a single filer with a MAGI of $210,000, which is $10,000 over the $200,000 threshold. Even if you had $80,000 of net investment income that year, the tax only applies to the smaller number: the **$10,000 you are over the line**.

NIIT owed: **$10,000 × 3.8% = $380**.

Flip it around. A single filer with MAGI of $400,000 and only $5,000 of net investment income (most of their income is W-2 wages) would compare: MAGI over the threshold is $200,000, net investment income is $5,000. The smaller number is $5,000.

NIIT owed: **$5,000 × 3.8% = $190**.

**The practical effect:** a very high-earning W-2 household with little investment income can owe almost nothing in NIIT, while a retiree with modest wages but a large capital gain from selling a rental property can owe a meaningful amount. Income composition matters more than total income here.

## What counts as net investment income

Net investment income generally includes:

- **Interest** (bank accounts, bonds, CDs)
- **Dividends** (qualified and ordinary)
- **Capital gains** (stock sales, the taxable gain on a home sale above the §121 exclusion, sale of a rental property)
- **Rental and royalty income** for most landlords (nonpassive rental income may be excluded only if the rental is also a trade or business under Section 162)
- **Income from a passive trade or business** you do not materially participate in
- Net gain from the disposition of property held for investment

It generally does **not** include:

- **Wages and salary**
- **Self-employment income** subject to SE tax (this income instead has its own surtax exposure under the Additional Medicare Tax, a separate rule)
- **Distributions from qualified retirement plans** (401(k), traditional and Roth IRAs, pensions)
- **Social Security benefits**
- **Income from an active trade or business** you materially participate in, including most S-corp pass-through income to an active owner-employee
- **Tax-exempt municipal bond interest**

> **Tip: Why active S-corp owners often dodge this tax entirely**
>
> If you **materially participate** in your S-corp (meaning you actively work in the business, not just own stock), the ordinary business income flowing to you on your K-1 is generally **excluded** from net investment income. This is one reason the [S-corp election](https://elevatedtaxstrategies.com/tax-planning/s-corp-election-mechanics/) is attractive for active owners above the NIIT thresholds: the wages are not NIIT income, and the active pass-through profit usually is not either.
>
> Rental real estate held inside the same S-corp is a different story and usually a bad idea on its own terms. See [the S-corp rental real estate trap](https://elevatedtaxstrategies.com/tax-planning/s-corp-rental-real-estate-trap/).

## A worked example, start to finish

Let's walk through a married couple filing jointly with these 2026 numbers:

- W-2 wages (both spouses combined): **$280,000**
- Qualified dividends: **$18,000**
- Long-term capital gain from selling stock: **$40,000**
- Rental property net income (passive): **$12,000**

**Step 1, total MAGI:** $280,000 + $18,000 + $40,000 + $12,000 = **$350,000**

**Step 2, MAGI over the threshold:** $350,000 − $250,000 (MFJ threshold) = **$100,000**

**Step 3, net investment income:** dividends + capital gain + rental income = $18,000 + $40,000 + $12,000 = **$70,000** (wages are excluded entirely)

**Step 4, the lesser of the two:** $70,000 (net investment income) is smaller than $100,000 (MAGI over threshold), so **$70,000** is the taxable amount.

**Step 5, the tax:** $70,000 × 3.8% = **$2,660**

This couple owes **$2,660** in NIIT, on top of their regular federal income tax on the dividends, capital gain, and rental income. The wages never entered the NIIT calculation at all, except to help determine whether they crossed the threshold in the first place.

## How this tax shows up on your return

NIIT is reported on **Form 8960**, attached to your Form 1040. The form walks through:

- Lines 1-7: categories of investment income (interest, dividends, annuities, rental/royalty/passive business, capital gains, other)
- Line 8: total investment income
- Lines 9-11: allowable deductions allocable to that income (investment interest expense, state income tax allocable to investment income, and certain other expenses)
- Line 12: net investment income
- Lines 13-15: MAGI, the threshold, and how far over the threshold you are
- Line 16: the smaller of line 12 or line 15 (MAGI over threshold)
- Line 17: the tax, **3.8%** of line 16

If a tax software program or preparer is doing your return, this form generates automatically once your numbers cross the threshold. The important part is understanding **why** it appeared, not filling it out by hand.

## Legal ways to reduce or avoid NIIT

None of these are loopholes. They are mainstream planning moves that happen to also help with NIIT, because they either lower MAGI or lower net investment income.

**Make eligible pre-tax retirement contributions.** Traditional 401(k) deferrals and *deductible* traditional IRA contributions can reduce current-year MAGI. IRA deductibility depends on income and retirement-plan coverage; Roth and nondeductible contributions do not reduce MAGI. These moves shrink NIIT only when the MAGI-over-threshold amount is the smaller side of the calculation.

**Harvest capital losses against gains.** Realized losses offset realized gains dollar for dollar before the NIIT calculation even starts. If you expect a large gain this year, check whether any losing positions make sense to sell in the same year. We cover the mechanics in [tax-loss harvesting for high earners](https://elevatedtaxstrategies.com/tax-planning/tax-loss-harvesting-high-earners/).

**Give appreciated assets instead of cash.** Donating appreciated stock you have held more than a year, rather than selling it and donating the cash, avoids recognizing the capital gain at all. Compare the donor-advised fund and direct-giving routes in our [guide to the tradeoffs](https://elevatedtaxstrategies.com/tax-planning/donor-advised-funds-vs-direct-giving/).

**Time a Roth conversion carefully.** Roth conversions themselves are not investment income, but they raise MAGI in the year of the conversion, which can push other investment income over the threshold for that single year. Converting in a lower-income year, or spreading a large conversion across several years, is worth modeling before you convert.

**Check whether rental activity is both nonpassive and a trade or business.** Real estate professional status plus material participation can make a rental nonpassive, but that alone does not remove it from NIIT. The rental must also rise to a Section 162 trade or business (or meet the IRS safe harbor). Do not assume an exclusion based only on your job title or hours.

**Consider installment sale treatment on a large property sale.** Spreading the gain from a sale over several years, rather than recognizing it all in one year, can keep you under the threshold in some of those years instead of stacking the entire gain into a single year that triggers NIIT at full force.

> **Heads up: Do not let NIIT drive the whole decision**
>
> Every move above has its own tax and economic tradeoffs that matter far more than the 3.8%. A $40,000 capital gain pushed into a lower-income year still gets taxed at the regular long-term capital gains rates. NIIT is the smaller layer on top. Model the full picture with your tax professional before restructuring a sale or a conversion around this one surtax.

## Common questions

### What is net investment income tax, in one sentence?

It is a flat 3.8% federal surtax on interest, dividends, capital gains, and passive rental or business income, owed only once your MAGI crosses a fixed dollar threshold for your filing status.

### Does NIIT apply to my paycheck?

No. Wages and self-employment income are never net investment income. They can, however, push your MAGI over the threshold, which then exposes your separate investment income to the tax.

### Is NIIT the same as the Additional Medicare Tax?

No. They are two different surtaxes that often get confused. The Additional Medicare Tax is 0.9% on wages and self-employment income above a similar threshold. NIIT is 3.8% on investment income. A high earner with both wage income and investment income can owe both, on different pieces of income.

### Does selling my primary home trigger NIIT?

Generally only on the portion of gain above the home-sale exclusion ($250,000 single, $500,000 married filing jointly, subject to the usual ownership and use tests). Gain excluded under that rule is also excluded from net investment income.

### Do retirement account withdrawals count toward NIIT?

Distributions from qualified plans like a 401(k) or traditional IRA are excluded from net investment income, but they do count toward MAGI. A large required distribution can push you over the threshold and expose other investment income to the tax, even though the distribution itself is not taxed under NIIT.

### Can an S-corp election help me avoid this tax?

For an owner who is actively working in the business, ordinary S-corp pass-through income is generally excluded from net investment income. It is one of several factors in the S-corp decision, not a reason by itself to elect. See our breakdown of [when an S-corp actually saves money](https://elevatedtaxstrategies.com/tax-planning/llc-vs-s-corp-tax-math-by-income-level/).

### Why did I owe NIIT this year when I didn't last year?

Because the thresholds never move, a modest raise, a one-time capital gain, or simply years of wage growth can push you over the line for the first time without any change in your investment strategy. Check whether a large one-time item, like a property sale, is the cause before assuming it is permanent.

### Is there a NIIT calculator I can use?

The math is simple enough to do by hand using the lesser-of formula above: compute net investment income, compute MAGI over your threshold, take the smaller number, and multiply by 3.8%. Software will do it automatically on Form 8960 once your numbers are entered.

## Ready to talk through your situation?

The moves that actually reduce NIIT depend on the shape of your income: how much is wages, how much is capital gains, and whether a sale is coming up this year or could be timed differently. A [Tax Discovery](https://elevatedtaxstrategies.com/discovery/) call is free, runs on Google Meet, comes with no pitch, and gets you free advice either way. If [tax planning](https://elevatedtaxstrategies.com/services/tax-planning-advisory/) around an upcoming sale or conversion makes sense, we'll walk you through it. If it doesn't, we'll tell you that too.