Quick Answer
The net investment income tax (NIIT) is a 3.8% surtax on investment income for individuals with modified adjusted gross income over $200,000 (single) or $250,000 (married filing jointly). It affects roughly 3% of taxpayers but can cost high earners thousands annually.
Best Answer
Michelle Woodard, Tax Policy Analyst
Best for individuals earning over $200K with significant investment portfolios
How the net investment income tax works
The Net Investment Income Tax (NIIT) is a 3.8% surtax that applies to the lesser of: (1) your net investment income, or (2) the amount by which your modified adjusted gross income (MAGI) exceeds the threshold ($200,000 single, $250,000 married filing jointly, $125,000 married filing separately).
This means if you're single with $300,000 MAGI and $50,000 in investment income, you pay 3.8% tax on $50,000 (the lesser amount), resulting in $1,900 in additional tax.
What counts as net investment income
Taxable investment income includes:
What's excluded:
Example: High earner with mixed income
Sarah, filing single, has:
Her MAGI is $255,000 ($180,000 + $35,000 + $40,000). Her net investment income is $75,000 ($35,000 + $40,000).
NIIT calculation:
Strategies to reduce NIIT
Tax-loss harvesting: Realize capital losses to offset gains. If Sarah had $20,000 in capital losses, her net investment income drops to $55,000, reducing NIIT to $55,000 × 3.8% = $2,090.
Municipal bonds: Interest from tax-exempt municipal bonds doesn't count as investment income. Converting $30,000 from taxable bonds to munis could save Sarah $1,140 in NIIT (plus regular income tax).
Retirement account contributions: While retirement distributions aren't subject to NIIT, maximizing pre-tax contributions reduces your MAGI. Contributing $23,500 to a 401(k) could lower Sarah's MAGI to $231,500, reducing her NIIT exposure.
Key factors that affect NIIT liability
What you should do
Review your investment portfolio allocation and consider moving high-yield investments to tax-deferred accounts. If you're close to the MAGI thresholds, explore ways to defer income or accelerate deductions. Use our return scanner to identify missed opportunities to reduce your NIIT liability.
Key takeaway: The 3.8% NIIT can cost high earners thousands annually, but strategic planning around the $200,000/$250,000 thresholds and investment allocation can significantly reduce this burden.
Key Takeaway: The 3.8% NIIT applies to investment income when MAGI exceeds $200K/$250K, but strategic tax-loss harvesting and retirement contributions can reduce exposure.
NIIT thresholds and tax impact by filing status
| Filing Status | MAGI Threshold | Tax Rate | Example Impact |
|---|---|---|---|
| Single | $200,000 | 3.8% | $1,000 investment income = $38 tax |
| Married Filing Jointly | $250,000 | 3.8% | $1,000 investment income = $38 tax |
| Married Filing Separately | $125,000 | 3.8% | $1,000 investment income = $38 tax |
| Head of Household | $200,000 | 3.8% | $1,000 investment income = $38 tax |
More Perspectives
Robert Kim, Tax Return Analyst
Best for investors aged 50+ who may cross NIIT thresholds due to portfolio growth
Planning for NIIT in retirement transition
As you approach retirement, the NIIT becomes particularly important because your income mix changes dramatically. You might have lower W-2 wages but higher investment income from years of portfolio growth.
The retirement income shift
Consider John, age 62, who recently retired:
In year three, John pays NIIT on $10,000 ($210,000 - $200,000 threshold), costing him $380 annually.
Asset location strategy for retirees
Before retirement: Move dividend-heavy stocks and REITs into 401(k)/IRA accounts. Keep tax-efficient index funds in taxable accounts.
After retirement: Consider Roth conversions during low-income years to reduce future required minimum distributions that could push you over NIIT thresholds.
Municipal bond considerations
For retirees in high tax brackets, municipal bonds become more attractive because they avoid both regular income tax and NIIT. A retiree in the 24% bracket facing NIIT saves 27.8% total (24% + 3.8%) on muni bond interest.
Key takeaway: Retirement income planning should consider NIIT thresholds, especially as portfolio values grow and income sources shift from wages to investments.
Key Takeaway: Retirement transitions can unexpectedly trigger NIIT as investment income grows while wage income disappears, requiring strategic asset location planning.
Michelle Woodard, Tax Policy Analyst
Best for business owners who have both active business income and passive investments
Business income vs. investment income for NIIT
As a business owner, understanding what counts as "net investment income" versus active business income is crucial for NIIT planning. The key test is "material participation."
Material participation rules
If you materially participate in your business, the income isn't subject to NIIT. You materially participate if you meet any of these tests:
Example: Restaurant owner with rental property
Maria owns a restaurant (active business) and two rental properties (passive). Her income:
Her MAGI is $255,000. Net investment income is $75,000 ($45,000 + $30,000).
NIIT applies to the lesser of $75,000 (investment income) or $55,000 (excess over $200,000 threshold).
Additional tax: $55,000 × 3.8% = $2,090
Real estate professional election
If Maria qualifies as a real estate professional (750+ hours in real estate activities annually, more than any other activity), her rental income wouldn't be subject to NIIT. This election could save her $1,710 annually ($45,000 × 3.8%).
S-corporation strategy
Business owners can elect S-corp status to convert some business income to wages (not subject to NIIT) and some to distributions. However, wages are subject to payroll taxes, so this requires careful analysis.
Key takeaway: Business owners can often restructure activities or elections to minimize NIIT exposure, particularly through real estate professional status or S-corp elections.
Key Takeaway: Business owners can minimize NIIT through material participation documentation and strategic elections like real estate professional status.
Sources
- IRS Publication 550 — Investment Income and Expenses
- IRC Section 1411 — Net Investment Income Tax statute
Reviewed by Michelle Woodard, Tax Policy 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.