Managing the 3.8% Investment Tax
The net investment income tax adds 3.8% to interest, dividends, capital gains, rents, and passive business income once modified AGI passes $200,000 single or $250,000 joint. Those thresholds are not indexed, so more households cross them every year. The tax falls on the smaller of your investment income or your income above the line, so lowering either one lowers the bill.
Reviewed by Ebot Mbi, CPA, EA · Last reviewed October 9, 2026
Who it fits
- Single filers above $200,000 or joint filers above $250,000 of modified AGI
- Owners with rental property, passive business interests, or large portfolios
- Anyone planning a large one-time gain, such as selling a business interest or real estate
- Business owners who can document material participation in their business
Who it's not for
- Households well below the thresholds, even in a high-gain year
- Taxpayers whose income is almost all wages or active business income, which the tax does not reach
- Anyone who would restructure an investment only for a 3.8% saving at the cost of a worse investment
How it works
Net investment income includes interest, dividends, capital gains, rents, royalties, non-qualified annuities, and income from businesses in which you do not materially participate. It does not include wages, self-employment income, distributions from IRAs and qualified plans, tax-exempt interest, or home-sale gain excluded under §121.
The first approach is to lower modified AGI. Pre-tax 401(k) deferrals, health savings account contributions, and deductible retirement plan contributions for business owners all reduce it. Spreading a large gain across years with a true installment sale keeps more of each year under the line.
The second approach is to change the character of the income. Income from a business in which you materially participate is not net investment income. Rental income can be excluded for a qualifying real estate professional who also materially participates in the rentals. Municipal bond interest is outside the tax altogether.
The third approach is to reduce the gains themselves. Harvesting losses, choosing high-basis lots when you sell, and giving appreciated stock to charity instead of selling it all reduce net investment income.
Trusts and estates face the same 3.8% at a much lower income level, the start of the top trust bracket, indexed for inflation each year. Distributing income to beneficiaries can move it to lower-taxed hands.
Illustrative example
Illustrative: a married couple filing jointly has $230,000 of wages and $80,000 of dividends and capital gains. One spouse is not yet contributing to the workplace 401(k) and starts deferring the full $24,500.
- Before: MAGI = $230,000 + $80,000 = $310,000
- Excess over threshold: $310,000 - $250,000 = $60,000
- NIIT base is the smaller of $80,000 or $60,000 = $60,000; tax = $60,000 x 3.8% = $2,280
- After: wages = $230,000 - $24,500 = $205,500; MAGI = $205,500 + $80,000 = $285,500
- Excess: $285,500 - $250,000 = $35,500; tax = $35,500 x 3.8% = $1,349
- NIIT saved: $2,280 - $1,349 = $931, in addition to the regular income tax deferred on $24,500
In this illustration, one 401(k) election cuts the 3.8% tax by $931 a year on top of the regular income tax deferral.
The rules
| Rule | Citation |
|---|---|
| A 3.8% tax applies to the smaller of net investment income or modified AGI above $200,000 single or $250,000 joint; the thresholds are not indexed. | IRC §1411 |
| Income from a trade or business in which the taxpayer materially participates is generally not net investment income. | IRC §1411(c)(2) |
| Distributions from qualified plans and IRAs are excluded from net investment income. | IRC §1411(c)(5) |
| A real estate professional who materially participates in rentals can qualify for a safe harbor treating rental income as non-passive business income. | Treas. Reg. §1.1411-4(g)(7) |
Watch-outs
- Material participation is tested activity by activity and needs records of hours. The IRS frequently audits real estate professional claims.
- Retirement distributions are not net investment income but they do raise MAGI, which can push other investment income into the tax.
- Year-end loss harvesting can trigger the wash-sale rule if you buy back the same or substantially identical securities within 30 days.
- The tax is not withheld automatically. Cover it through withholding or estimated payments to avoid an underpayment penalty.
What we do
We project your MAGI and net investment income for the year, show which lever lowers the tax most, and document material participation where it applies. We coordinate gain timing with your investment advisor and compute Form 8960 on your return.
Questions
Does the tax apply to my S corporation income?
Not if you materially participate in the business. If you are a passive owner, your share of the income is generally net investment income.
Does it apply when I sell my home?
Only to gain above the $250,000 single or $500,000 joint exclusion. The excluded part is not subject to the tax.
Will the thresholds go up with inflation?
No. They are fixed in the statute at $200,000 single and $250,000 joint.