The capital gains tax surcharge is the 3.8% Net Investment Income Tax, an extra federal levy that applies to investment profits once your modified adjusted gross income crosses $200,000 for single filers, $250,000 for married couples filing jointly, or $125,000 if married filing separately. On top of the 20% top long-term capital gains rate, it brings the combined federal rate to 23.8% before any state tax. For most investors who sit in the 15% long-term bracket, the surcharge lifts the combined rate to 18.8%.
Who Pays the 3.8% Surcharge
The trigger is your modified adjusted gross income (MAGI), not your investment income alone. The thresholds:
- Married filing jointly or qualifying surviving spouse: $250,000
- Single or head of household: $200,000
- Married filing separately: $125,000
These numbers are fixed in the statute and have never been indexed for inflation, so more households cross them each year as wages and asset values climb.1Internal Revenue Service. Questions and Answers on the Net Investment Income Tax
For most people, MAGI equals regular AGI. The one adjustment that matters for Americans working abroad: if you claim the foreign earned income exclusion, you add the excluded amount back when figuring MAGI for this surcharge, which can push expats over the line even when their Form 1040 taxable income looks well below it.2Internal Revenue Service. Topic No. 559, Net Investment Income Tax
What Counts as Net Investment Income
The surcharge reaches the net profit from investments, not the gross. The main categories:
- Capital gains from stocks, bonds, mutual funds, ETFs, and investment real estate
- Dividends and interest, both qualified and ordinary, including CD and taxable bond interest
- Rental and royalty income, unless the activity is an active trade or business
- Passive business income from an entity where you don’t materially participate
- The taxable portion of non-qualified annuity payments
“Net” matters. You subtract allowable investment-related expenses before applying the 3.8% rate. Investment interest expense is the most common deduction.3eCFR. 26 CFR 1.1411-4 – Definition of Net Investment Income For 2026 returns, investment advisory fees and other miscellaneous itemized deductions become deductible again after being suspended under the Tax Cuts and Jobs Act. State and local income taxes allocable to investment income can also reduce the base, using a reasonable allocation method to split them between investment and non-investment income.4Internal Revenue Service. 2025 Instructions for Form 8960
Active vs. Passive Business Income
Whether income from a business you own falls into the surcharge depends on how involved you are. The most common safe harbor is 500 or more hours of participation per year. Clear that bar and the income stays outside the surcharge; fall short and it’s passive, and the 3.8% applies.5Office of the Law Revision Counsel. 26 U.S. Code 1411 – Imposition of Tax The distinction bites hardest for S corporation and partnership owners who have stepped back from daily operations but still draw significant income.
Income That Stays Out
Several income types are not net investment income, though they do count toward MAGI and can push you over the threshold:
- Wages, salaries, and bonuses
- Distributions from 401(k), 403(b), 457(b), traditional IRA, and Roth IRA accounts1Internal Revenue Service. Questions and Answers on the Net Investment Income Tax
- Social Security benefits and unemployment compensation6Internal Revenue Service. Net Investment Income Tax
- Tax-exempt interest from municipal bonds2Internal Revenue Service. Topic No. 559, Net Investment Income Tax
- Self-employment income from a business where you materially participate
- Alimony received under agreements executed before 20196Internal Revenue Service. Net Investment Income Tax
The retirement-plan exclusion trips retirees up. A large IRA distribution or Roth conversion isn’t itself taxed by the 3.8% surcharge, but it can lift total MAGI over the threshold, causing the surcharge to hit your other investment income in that year.
How the Surcharge Is Calculated
The IRS uses a lesser-of formula. The 3.8% rate applies to the smaller of two numbers: your total net investment income, or the amount by which your MAGI exceeds your filing-status threshold.5Office of the Law Revision Counsel. 26 U.S. Code 1411 – Imposition of Tax
Take a single filer with $230,000 MAGI and $10,000 in net investment income. MAGI exceeds the $200,000 threshold by $30,000, but investment income is only $10,000. The smaller figure wins: $10,000 × 3.8% = $380.
Now change the second number. Same $230,000 MAGI, but $40,000 in net investment income. The excess over the threshold is still $30,000, and this time that’s the smaller number. Surcharge: $30,000 × 3.8% = $1,140. The remaining $10,000 of investment income escapes because it falls within the threshold cushion.
Selling Your Home
A primary-residence sale doesn’t automatically trigger the surcharge. You can exclude up to $250,000 of gain, or $500,000 for a joint return, if you owned and lived in the home for at least two of the last five years.7Office of the Law Revision Counsel. 26 USC 121 – Exclusion of Gain From Sale of Principal Residence Gain that falls within the exclusion isn’t net investment income at all.
Only the gain above the exclusion is exposed. If a married couple clears $600,000 of profit, the first $500,000 is excluded and the remaining $100,000 flows into net investment income. Whether they owe the surcharge still depends on total MAGI. Investment properties and second homes get no exclusion, so the full gain counts.
How to Reduce the Surcharge
You have two levers: shrink the net investment income itself, or hold total MAGI below the threshold.
Harvest Losses
Selling losing positions offsets gains and directly reduces net investment income. With $50,000 of gains and $20,000 of realized losses, only $30,000 enters the calculation. Losses beyond gains can deduct up to $3,000 against other income and carry forward indefinitely.8Internal Revenue Service. Topic No. 409, Capital Gains and Losses Watch the wash-sale rule: buying the same or substantially identical security within 30 days before or after the sale disallows the loss.
Spread a Big Sale With an Installment Sale
A one-year gain on real estate or a business can spike MAGI far above the threshold. An installment sale under IRC Section 453 spreads recognized gain across the years you receive payments, potentially keeping each year under the trigger. Each payment splits proportionally into taxable gain and return of basis using a gross profit percentage that stays constant over the note.9Internal Revenue Service. Publication 537, Installment Sales The cost is credit risk; you become the lender.
Retirement Contributions and Charitable Gifts
Maximizing deductible contributions to a traditional IRA or an employer retirement plan lowers AGI, which is the starting point for MAGI. Charitable donations above the standard deduction cut AGI for itemizers. Donating appreciated stock directly to charity avoids recognizing the gain at all, keeping it out of both income and the surcharge base.
Shift Fixed Income Into Munis
Municipal bond interest is excluded from net investment income. Moving part of a taxable fixed-income portfolio into munis reduces the investment income side of the calculation, though the strategy only pays off when the tax savings beat the yield gap.
Filing and Estimated Payments
You report the surcharge on Form 8960, which runs the net investment income calculation and applies the lesser-of formula. The result carries to Schedule 2 of Form 1040 as an additional tax.10Internal Revenue Service. About Form 8960, Net Investment Income Tax – Individuals, Estates, and Trusts
If you expect to owe the surcharge, build it into your quarterly estimated payments. For 2026, the deadlines are April 15, June 15, and September 15, 2026, plus January 15, 2027. You can skip the January payment by filing and paying in full by January 31, 2027. The IRS charges interest on underpayments at a rate tied to the federal short-term rate, which sits at 6% as of early 2026.11Internal Revenue Service. Internal Revenue Bulletin 2026-8 A separate failure-to-pay penalty of 0.5% per month, capped at 25%, applies if a balance remains after filing.12Internal Revenue Service. Failure to Pay Penalty A mid-year event like a business sale or a concentrated stock liquidation usually calls for a larger payment that specific quarter, not a smooth split.
The Combined Federal Rate
The surcharge sits on top of the regular long-term capital gains rates, which for 2026 are 0%, 15%, or 20% depending on taxable income. A single filer above $545,500 in taxable income pays the top 20% rate on long-term gains, bringing the combined federal rate to 23.8%.5Office of the Law Revision Counsel. 26 U.S. Code 1411 – Imposition of Tax Short-term gains from assets held one year or less are taxed as ordinary income up to 37%, and the surcharge can apply there too, pushing the effective federal rate to 40.8% in the top bracket. State tax, ranging from 0% to over 13%, comes on top.
Most investors sit in the 15% long-term bracket, where the surcharge lifts the combined rate to 18.8%. That’s the rate that surprises people in the year they sell a home, exercise stock options, or take a large capital gains distribution from a mutual fund they didn’t even trade.