Do You Pay the Obamacare Tax on Capital Gains?

The Obamacare tax on capital gains is the Net Investment Income Tax, a 3.8% federal surtax that applies to investment profits once your modified adjusted gross income (MAGI) crosses $200,000 as a single filer or $250,000 as a married couple filing jointly.¹ Congress enacted it as part of the 2010 healthcare reform law, and it has applied to tax years starting January 1, 2013.² If your income stays below the threshold for your filing status, you don’t owe it, no matter how large the gain.

Who Owes the 3.8% Surtax

The tax kicks in at these MAGI levels, which have not been adjusted since 2013 and are not indexed for inflation:³

Married filing jointly or qualifying surviving spouse: $250,000
Single or head of household: $200,000
Married filing separately: $125,000

MAGI is generally your adjusted gross income with certain foreign-earned-income exclusions added back.⁴ Because the thresholds have been frozen for over a decade, many dual-income households now cross the line without any unusual investment event.

The Lesser-of Rule That Decides What You Actually Pay

The 3.8% rate doesn’t apply to all of your investment income. It applies to the smaller of two numbers: your net investment income for the year, or the amount by which your MAGI exceeds the threshold.¹ That one rule is what makes the tax more forgiving than it first appears.

Take a single filer with $270,000 of MAGI and $90,000 of net investment income. The MAGI excess is $70,000. That’s less than the $90,000 in investment income, so the tax base is $70,000. The NIIT comes to $2,660.²

Flip the ratio and the bite shrinks. A single filer with $205,000 of MAGI and $40,000 of investment income has only $5,000 of MAGI excess. The tax base is $5,000, and the NIIT is just $190. When your income barely clears the threshold, the surtax is modest even if your gains are large.

What Capital Gains and Other Investment Income Count

Net investment income covers the common forms of portfolio and passive income:²

Capital gains from selling stocks, bonds, mutual fund shares, investment real estate, and other appreciated assets
Interest and dividends from bank accounts, bonds, stocks, and mutual funds
Rental and royalty income
Your share of income from a partnership or S corporation in which you don’t materially participate
The taxable portion of non-qualified annuity payments

Several categories are specifically excluded:⁵

Wages and self-employment income (those face payroll taxes instead)
Distributions from 401(k)s, traditional and Roth IRAs, 403(b) plans, and government 457(b) plans
Social Security benefits
Tax-exempt interest, such as income from municipal bonds
Profits from an active business in which you materially participate

So gains inside your retirement accounts don’t trigger the NIIT when you sell holdings there, and withdrawals from those accounts aren’t counted as investment income either. Selling appreciated stock in a regular taxable brokerage account, by contrast, is a classic NIIT trigger.

How the NIIT Stacks on Top of Capital Gains Rates

The 3.8% surtax sits on top of your regular federal capital gains rate. Long-term gains on assets held more than a year are taxed federally at 0%, 15%, or 20% depending on your taxable income, with the 20% rate starting at $545,500 for single filers and $613,700 for married couples filing jointly in 2026.⁶⁷ Add the NIIT and the top effective federal rate on long-term capital gains reaches 23.8%.

Short-term gains, on assets held a year or less, are taxed at ordinary rates that top out at 37% for 2026.⁷ Layer the 3.8% NIIT on top and a high-income taxpayer faces a combined federal rate of 40.8%. That gap is a strong argument for holding appreciated assets past the one-year mark whenever possible.

State taxes come on top of all that. Most states tax capital gains as ordinary income, and in the highest-tax states the combined federal-plus-state rate on short-term gains can exceed 50%.

Selling Your Home

Selling your primary residence doesn’t automatically create NIIT exposure. The Section 121 exclusion lets you exclude up to $250,000 of gain ($500,000 if married filing jointly) if you’ve owned and lived in the home for at least two of the five years before the sale.⁸ The excluded portion is ignored for NIIT purposes.²

Any gain above the exclusion counts as investment income, and the recognized portion can push your MAGI across the threshold even when your regular paycheck would not have. Imagine a married couple with $200,000 of ordinary income who sell their home for a $600,000 gain. After the $500,000 exclusion, $100,000 of gain is recognized. Their MAGI becomes $300,000, which exceeds the $250,000 joint threshold by $50,000. The NIIT is 3.8% of the lesser of $100,000 or $50,000, producing a $1,900 bill.² If the same couple’s MAGI stayed below $250,000 even with the recognized gain, no NIIT would apply.

Deductions That Shrink Your Investment Income

Net investment income is a net figure. You subtract allowable deductions before applying the 3.8% rate, and each dollar of deduction cuts the tax directly. The most useful categories:⁹

Investment interest expense, including margin interest, within the regular investment interest limitation
Rental property expenses such as depreciation, repairs, and property management fees
Investment advisory fees paid on taxable accounts
The portion of state income taxes allocable to investment income
Penalties for early withdrawal of savings, such as breaking a CD before maturity

Ways to Reduce What You Owe

Because the tax depends on both your investment income and your MAGI, lowering either shrinks the bill:

Harvest capital losses. Selling losers to offset winners cuts your net investment income directly, and carried-forward losses from prior years do the same.
Shift income into tax-deferred accounts. Contributions to 401(k)s, traditional IRAs, and health savings accounts reduce your MAGI, which can drop you below the threshold entirely. Future growth in those accounts stays outside the NIIT.
Spread a big sale across tax years. Splitting the sale of a highly appreciated asset over two years can keep each year’s MAGI closer to the threshold.
Give appreciated assets to charity. Donating stock directly, or using a charitable remainder trust, avoids realizing the gain, which removes it from both your investment income and your MAGI.
If you hold a passive business interest, increasing your involvement to the material-participation standard reclassifies that income as active and takes it outside the NIIT.

How to Report and Pay It

You report the NIIT on IRS Form 8960, filed with your return any year your MAGI exceeds the threshold.⁵ The surtax is subject to the same estimated tax rules as the rest of your federal income tax, so a one-time event like a business sale or a large stock sale often needs a quarterly estimated payment or extra withholding to avoid an underpayment penalty.³

The usual safe harbor applies: you generally avoid a penalty if your total withholding and estimated payments cover at least 90% of your current-year tax or 100% of last year’s (110% if your prior-year AGI exceeded $150,000).¹⁰ The penalty is figured separately for each quarterly installment, so catching up late in the year doesn’t erase a miss earlier on.

1
Internal Revenue Service. Net Investment Income Tax
2
Internal Revenue Service. Questions and Answers on the Net Investment Income Tax
3
Internal Revenue Service. Topic No. 559, Net Investment Income Tax
4
Internal Revenue Service. Modified Adjusted Gross Income
5
Internal Revenue Service. 2025 Instructions for Form 8960 – Net Investment Income Tax
6
Internal Revenue Service. Topic No. 409, Capital Gains and Losses
7
Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
8
Office of the Law Revision Counsel. 26 USC 121 – Exclusion of Gain from Sale of Principal Residence
9
eCFR. 26 CFR 1.1411-4 – Definition of Net Investment Income
10
Internal Revenue Service. 2025 Instructions for Form 2210 – Underpayment of Estimated Tax by Individuals, Estates, and Trusts