Quick Answer
The Net Investment Income Tax (NIIT) is a 3.8% tax on investment income that applies when your modified adjusted gross income exceeds $200,000 (single) or $250,000 (married filing jointly). Created by the Affordable Care Act, it generates revenue for Medicare but is separate from the 1.45% Medicare tax on wages.
Best Answer
Marcus Rivera, Compensation & Benefits Analyst
Best for high-income earners trying to understand how NIIT affects their investment strategy
What is the Net Investment Income Tax (NIIT)?
The Net Investment Income Tax is a 3.8% federal tax that applies to investment income for high-income taxpayers. Despite its connection to Medicare funding, NIIT is completely separate from the Medicare taxes withheld from your paycheck. It was created by the Affordable Care Act in 2013 to help fund Medicare expansion.
NIIT kicks in when your modified adjusted gross income (MAGI) exceeds $200,000 if you're single, $125,000 if married filing separately, or $250,000 if married filing jointly. The tax applies to the lesser of your net investment income or the amount by which your MAGI exceeds these thresholds.
Example: How NIIT is calculated
Let's say you're single with $180,000 in salary and $40,000 in investment income, for a total MAGI of $220,000:
Step 1: Determine excess MAGI
$220,000 - $200,000 threshold = $20,000 excess
Step 2: Compare to investment income
Lesser of $40,000 (investment income) or $20,000 (excess MAGI) = $20,000
Step 3: Calculate NIIT
$20,000 × 3.8% = $760
You'd pay $760 in NIIT, even though you had $40,000 in investment income. The tax is limited by how much your total income exceeds the threshold.
Types of investment income subject to NIIT
Income that's taxed:
Income that's exempt:
How NIIT relates to Medicare taxes
While NIIT revenue goes to Medicare, it operates independently from regular Medicare taxes. Here's the breakdown:
Regular Medicare tax: 1.45% on all wages (employee share) + 1.45% employer share = 2.9% total
Additional Medicare Tax: 0.9% on wages over $200K/$250K (employee only)
NIIT: 3.8% on investment income when MAGI exceeds thresholds
These are three separate calculations. A high earner could potentially pay all three:
Planning strategies to minimize NIIT
Asset location: Keep income-generating investments in tax-deferred accounts like 401(k)s and IRAs. Dividends and capital gains inside these accounts don't trigger NIIT until distributed.
Tax-loss harvesting: Offset capital gains with losses to reduce net investment income subject to NIIT.
Municipal bonds: Interest from municipal bonds is exempt from NIIT (and regular income tax).
Active vs. passive business income: If you materially participate in a business, that income isn't subject to NIIT. Consider increasing your involvement in businesses you own.
Income timing: Spread large capital gains across multiple years to stay under MAGI thresholds when possible.
What you should do
1. Calculate your MAGI including all income sources to see if you're near the thresholds
2. Review your investment allocation — consider moving high-income investments to tax-deferred accounts
3. Plan capital gains timing — avoid bunching large gains in a single year
4. Consider municipal bonds for current income needs without NIIT exposure
5. Make estimated payments — NIIT isn't withheld from paychecks, so you'll need to pay quarterly or increase withholding
Use our paycheck calculator to understand how your wages affect overall tax liability, then plan investment strategies around NIIT thresholds.
Key takeaway: NIIT is a separate 3.8% tax on investment income for high earners that funds Medicare but operates independently from regular Medicare taxes, requiring separate planning and estimated payments.
*Sources: [IRS Form 8960 Instructions](https://www.irs.gov/pub/irs-pdf/i8960.pdf), [IRS Publication 550](https://www.irs.gov/pub/irs-pdf/p550.pdf)*
Key Takeaway: NIIT is a separate 3.8% tax on investment income for high earners that funds Medicare but operates independently from regular Medicare taxes, requiring separate planning and estimated payments.
NIIT vs. other Medicare taxes for 2026
| Tax Type | Rate | Income Threshold | Applies To | Withholding |
|---|---|---|---|---|
| Medicare Tax (employee) | 1.45% | All wages | Wages, salary | Yes - automatic |
| Additional Medicare Tax | 0.9% | $200K/$250K | Wages over threshold | Yes - when wages hit $200K |
| Net Investment Income Tax | 3.8% | $200K/$250K MAGI | Investment income only | No - estimated payments needed |
More Perspectives
Marcus Rivera, Compensation & Benefits Analyst
Best for pre-retirees with growing investment accounts who need to understand NIIT's impact on retirement planning
NIIT implications for retirement planning
As you approach retirement, NIIT becomes increasingly relevant because you're likely accumulating substantial investment assets while still earning peak wages. Understanding how NIIT works helps you make smarter decisions about retirement account contributions and withdrawal strategies.
The retirement account advantage
One of the most valuable aspects of retirement accounts is their NIIT exemption. Distributions from 401(k)s, traditional IRAs, Roth IRAs, and pensions are not considered "investment income" for NIIT purposes, even though they may be taxable for regular income tax.
This creates a significant advantage for asset location decisions. A $50,000 dividend portfolio in a taxable account might generate $760 in NIIT for someone over the income thresholds. The same portfolio inside a 401(k) or IRA generates no NIIT until funds are withdrawn — and even then, the withdrawals themselves aren't subject to NIIT.
Example: Pre-retiree at age 58
Consider someone earning $190,000 with $25,000 in investment income and taking a $35,000 hardship withdrawal from their 401(k):
Total MAGI: $250,000
Excess over $200,000 threshold: $50,000
NIIT: Lesser of $25,000 (investment income) or $50,000 (excess) = $25,000 × 3.8% = $950
The $35,000 401(k) distribution increases total income but isn't subject to NIIT itself.
Strategic planning for pre-retirees
Maximize tax-deferred contributions: Every dollar you contribute to a 401(k) or traditional IRA reduces current MAGI, potentially keeping you under NIIT thresholds while sheltering future investment returns from NIIT.
Roth conversion timing: Converting traditional retirement money to Roth creates taxable income that could push you over NIIT thresholds, but the conversion itself isn't "investment income." Plan conversions during lower-income years.
Asset allocation by account type: Keep high-dividend stocks, REITs, and other income-generating investments in retirement accounts. Hold growth stocks (which generate less current income) in taxable accounts.
Key takeaway: Retirement account distributions are exempt from NIIT, making maximizing contributions and strategic asset location crucial for pre-retirees facing potential NIIT exposure.
Key Takeaway: Retirement account distributions are exempt from NIIT, making maximizing contributions and strategic asset location crucial for pre-retirees facing potential NIIT exposure.
Sarah Chen, Payroll Tax Analyst
Best for people juggling W-2 jobs plus investment or rental income who need to understand their total NIIT exposure
NIIT complexity with multiple income streams
When you have multiple W-2 jobs plus investment or rental income, calculating NIIT becomes more complex because it depends on your total modified adjusted gross income from all sources. This means you need to track everything together, not just your investment income in isolation.
Example: Multiple jobs plus rental property
Say you earn $90,000 from a full-time job, $60,000 from consulting work, and have $15,000 in net rental income from an investment property. Your total MAGI is $165,000 — well under the $200,000 NIIT threshold, so you pay no NIIT despite having investment income.
But if the consulting income jumps to $100,000, your MAGI becomes $205,000:
The rental income stayed the same, but higher consulting income triggered NIIT.
Planning considerations for multiple income streams
Income timing flexibility: If you control the timing of consulting income or can defer rental income through repairs/improvements, you might stay under NIIT thresholds.
Business vs. investment classification: Rental income is usually subject to NIIT, but if real estate is your business and you materially participate, it might be exempt. The distinction matters significantly.
Quarterly payment planning: With multiple income streams, you'll likely need to make estimated quarterly payments for both regular income tax and NIIT since there's no withholding on investment income.
Key takeaway: NIIT considers total income from all sources, so people with multiple jobs need to monitor their combined MAGI throughout the year to avoid underpayment penalties.
Key Takeaway: NIIT considers total income from all sources, so people with multiple jobs need to monitor their combined MAGI throughout the year to avoid underpayment penalties.
Sources
- IRS Form 8960 Instructions — Net Investment Income Tax — Individuals, Estates, and Trusts
- IRS Publication 550 — Investment Income and Expenses
Related Questions
Reviewed by Marcus Rivera, Compensation & Benefits Analyst on February 28, 2026
This content is for educational purposes only and is not a substitute for professional tax advice. Consult a qualified tax professional for advice specific to your situation.