A Comprehensive Guide to NIIT for High-Income Investors

The Net Investment Income Tax (NIIT) is an additional 3.8% surtax on certain investment income (like interest, dividends, capital gains, rental/royalty income, and non-qualified annuities) when your modified adjusted gross income (MAGI) exceeds certain thresholds. Most high earners get surprised because NIIT stacks on top of your normal investment taxes. The good news: you can often reduce NIIT exposure through retirement account contributions, tax-loss harvesting, real estate deductions, and charitable planning (like DAFs).

Last updated: February 11, 2026

The Net Investment Income Tax (NIIT) almost always tends to catch high earners by surprise, sometimes, it feels like new tax rules and stipulations (like the AMT) are flying out of the woodwork at every turn.

Call it what you want, the NIIT, an additional 3.8% tax on certain types of investment income for individuals with high modified adjusted gross incomes (MAGIs), is inconvenient. Still, proper planning can mitigate it or even completely avoid it.

Our NIIT guide dives into the basics, its impact on your overall tax liability, who it most likely affects, and most importantly, how you can reduce its impact through strategic financial planning.

If the NIIT feels like something new, it’s because it somewhat is.

The NIIT, introduced by the Affordable Care Act in 2013, aims to help fund Medicare. It applies an additional 3.8% tax on investment income for individuals and households exceeding specific income thresholds.

Investment income includes interest, dividends, capital gains, rental and royalty income, and non-qualified annuities, more on this below.

• $200,000 for single filers
• $250,000 for married couples filing jointly
• $125,000 for married couples filing separately

Let’s dive into the details of income the NIIT targets.

• Interest income (savings accounts, CDs, bonds)
• Dividends (qualified and non-qualified)
• Capital gains (profits from selling stocks, bonds, and real estate not used as a primary residence)
• Rental and royalty income (rental properties, intellectual property royalties)
• Non-qualified annuity distributions

The NIIT does not target your wages, benefits, or retirement plan distributions.

• Wages and W-2 income
• Unemployment compensation
• Social Security benefits
• Alimony
• Tax-exempt interest
• Self-employment income
• Distributions from qualified retirement plans (401(k)s, IRAs, etc.)

We know the NIIT targets high-income earners with substantial investment income, but who exactly fits our definition?

You’re affected if your MAGI exceeds the thresholds and you have net investment income.

Your Modified Adjusted Gross Income (MAGI) is typically used to determine eligibility for certain tax benefits and credits.

Simply put, MAGI is your total income (wages, investment income, and other sources) with specific deductions added back in.

The adjustments that need to be added back to AGI to calculate MAGI can vary depending on the specific tax provision. Still, they include things like tax-exempt interest (from municipal bonds), IRA contributions, passive losses or passive income, and more.

You can refer to the IRS instructions for Form 8960 for detailed information on calculating MAGI.

The NIIT calculation applies the 3.8% rate to the lesser of:

• Your net investment income, or
• The amount your MAGI exceeds the applicable threshold

Example: If Bob is a single filer with a MAGI of $250,000 and $60,000 in net investment income, the NIIT applies to $50,000 (the amount his MAGI exceeds the $200,000 threshold), resulting in a $1,900 tax.

Example: If Bob is a single filer with a MAGI of $250,000 and only $30,000 in net investment income, the NIIT applies to the lesser $30,000 figure, resulting in a $1,140 tax (3.8% of $30,000).

Before you whip out the Google Sheets and calculators, the NIIT is typically calculated by your tax planning software or financial planner. However, it’s still helpful to understand how the proverbial hot dog is made by walking through the process yourself.

1. 1.
   Determine your MAGI by adding your adjusted gross income (AGI) and any excluded foreign income.
2. 2.
   Identify net investment income by summing investment income and subtracting related expenses (e.g., investment interest expenses and advisory fees).
3. 3.
   Compare and apply the tax to the lesser amount.

Example calculation:

• AGI: $240,000
• Excluded foreign income: $10,000
• MAGI: $250,000
• Net investment income: $70,000
• Excess over threshold: $50,000 ($250,000 – $200,000 threshold for single filers)
• NIIT: 3.8% of $50,000 = $1,900

The most common way to minimize NIIT impact is through tax-advantaged accounts like 401(k)s, IRAs, and HSAs.

• Max out retirement and HSA contributions: These can reduce taxable income and, consequently, MAGI.
• Real estate deductions and planning: Rental property deductions can offset rental income with expenses like mortgage interest, property taxes, and depreciation. 1031 exchanges can defer capital gains taxes on investment property by reinvesting proceeds in similar properties.
• Tax-loss harvesting: Realize losses to offset capital gains and reduce net investment income.
• Charitable planning and DAFs: Charitable contributions can reduce MAGI. Donating appreciated stock can help avoid capital gains tax while generating a charitable deduction.
• Income deferral: If possible, defer income into a future year when your MAGI might be lower (often easiest to coordinate later in the year and via self-employment or variable income streams).

John maximizes his 401(k) and HSA contributions:

• Annual salary: $250,000
• Potential net investment income: $30,000
• 401(k) contribution limit (2024): $23,000
• HSA contribution limit (2024): $4,150
• Total contributions: $27,150 (assuming under 50, no catch-up)

MAGI before contributions: $250,000

MAGI after contributions: $222,850

• Excess over threshold: $22,850 ($222,850 – $200,000)
• NIIT applies to the lesser of $22,850 or $30,000 = $22,850
• NIIT liability: 3.8% of $22,850 = $868.30

If he were taxed the NIIT on the full $50,000 excess, he’d owe $1,900. Because he maxed out contributions, John saved $1,032 in NIIT.

Emily’s MAGI is $225,000. She harvests $20,000 in losses to offset capital gains:

• MAGI: $225,000
• Capital gains: $50,000
• Unrealized losses: $20,000
• Net capital gains after harvesting: $30,000

Emily’s MAGI exceeds the NIIT threshold by $25,000 ($225,000 – $200,000).

The NIIT applies to the lesser of net investment income ($30,000) or excess over threshold ($25,000), so NIIT is based on $25,000.

• NIIT liability after harvesting: 3.8% of $25,000 = $950

By tax-loss harvesting, Emily reduces her NIIT exposure and saves money versus a higher NIIT scenario.

Mike (MAGI: $240,000) owns rental properties and uses expenses + depreciation:

• MAGI: $240,000
• Rental income: $100,000
• Expenses: $50,000
• Depreciation: $40,000
• Net rental income: $10,000

Mike’s MAGI exceeds the threshold by $40,000.

NIIT applies to the lesser of net investment income ($10,000) or the excess over threshold ($40,000), so NIIT is based on $10,000.

• NIIT liability: 3.8% of $10,000 = $380

The Net Investment Income Tax can significantly impact high-income earners who also dabble in various forms of investing, but with strategic planning, you can reduce a meaningful portion of it, and in some cases avoid it.

It’s worth noting that NIIT isn’t the only tax concern once income levels are higher. For example, the Alternative Minimum Tax (AMT) can further complicate things, and you could potentially owe both taxes if you meet the criteria for each.

Remember, individual financial situations can be nuanced, personal goals, retirement timing, family needs, savings rates, and earning schedules all matter. Tailored advice from a qualified financial planner and tax professional can help connect the dots.

• Instructions and details on calculating NIIT: IRS Form 8960 – Net Investment Income Tax – Individuals, Estates, and Trusts
• Income definitions and examples: IRS Publication 525 – Taxable and Nontaxable Income
• Business expense details: IRS Publication 535 – Business Expenses

• NIIT is a surtax. It stacks on top of other investment taxes when MAGI crosses thresholds.
• It applies to investment income, not wages. But wages can push MAGI over the line and “activate” NIIT on investments.
• It’s calculated on the lesser of two numbers. Net investment income vs MAGI over the threshold.
• You can reduce exposure. Retirement accounts, HSAs, TLH, real estate deductions, and charitable strategies often help.
• High earners should model it annually. Especially in bonus/RSU years or large liquidation events.

No. NIIT requires net investment income. High wages alone don’t trigger NIIT without investment income.

Tax-exempt interest is generally excluded from NIIT, but the right approach depends on your state, bracket, and portfolio goals.

Holding longer may shift gains to long-term capital gains, but NIIT can still apply if MAGI exceeds thresholds when the gain is realized.