Net Investment Income Tax: MAGI Thresholds, 3.8% Surtax, and Form 8960

The Net Investment Income Tax is a 3.8% federal surtax on investment earnings owed by individuals whose modified adjusted gross income (MAGI) exceeds $200,000 for single filers or $250,000 for married couples filing jointly. The 3.8% doesn’t hit every dollar of investment income. It applies to the smaller of two figures: your net investment income for the year, or the amount by which your MAGI exceeds your filing-status threshold.¹ Congress enacted the tax in 2010, and the thresholds are written into the statute without any inflation adjustment.²

Who Crosses the Threshold

The line that triggers the surtax depends entirely on filing status:

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

There is no phase-in. Once your MAGI clears the threshold by a single dollar, the surtax mechanism engages.²

For most people, MAGI is the adjusted gross income shown on the tax return. The main adjustment applies to taxpayers who claim the foreign earned income exclusion under Section 911, who must add the excluded amount back when figuring MAGI for this tax.³ If you have no foreign income, your AGI and MAGI are the same number.

What Counts as Investment Income

The surtax targets income from capital rather than income from work. The main categories are interest, dividends (qualified and ordinary), capital gains, rental income, royalties, and income from non-qualified annuities.⁴ Business income counts too if the business is a passive activity, meaning you own a stake but don’t materially participate in operations.²

The tax applies to the net figure. You subtract deductible expenses tied to producing that income, such as investment advisory fees and investment interest expense, before applying the 3.8%.

Home Sale Gains

Selling your primary residence can generate a substantial capital gain, but Section 121 lets single filers exclude up to $250,000 of gain and joint filers up to $500,000, provided the home was your primary residence for at least two of the five years before the sale. The excluded portion is invisible to the surtax. Only gain above the exclusion enters the net investment income calculation.⁴ In most markets that means no surtax at all on a home sale; in high-appreciation areas, it can apply to the excess.

What the Surtax Does Not Reach

Earned income sits entirely outside the tax. Wages, salaries, tips, and self-employment income are not investment income and don’t carry the 3.8% charge, though they still count toward your MAGI and can push you over the threshold on your other income.⁴

Several other items are excluded from net investment income:

Distributions from traditional IRAs, 401(k)s, 403(b)s, 457(b) plans, and Roth accounts. The taxable portion of those withdrawals still increases MAGI, however, which can pull other investment income into range.
Social Security benefits and unemployment compensation.
Tax-exempt interest from municipal bonds, which is also excluded from MAGI.
Alimony received.
Operating income from a trade or business in which you materially participate.

The retirement piece catches people off guard. A large Roth conversion isn’t itself investment income, but it inflates MAGI and can cause dividends or capital gains that would otherwise sit below the threshold to become taxable at 3.8%.

How the 3.8% Is Calculated

Once you know your net investment income and your MAGI overage, the surtax is 3.8% of whichever number is smaller.¹

Take a single filer with a MAGI of $260,000, of which $80,000 is net investment income. The excess over the $200,000 threshold is $60,000. Because $60,000 is less than the $80,000 of investment income, the surtax is 3.8% of $60,000, or $2,280. The remaining $20,000 of investment income escapes the tax.

Flip the figures. Same filer, same $260,000 MAGI, but only $30,000 of net investment income. The MAGI excess is still $60,000, but investment income is now the smaller number. The surtax is 3.8% of $30,000, or $1,140. You’re never taxed on more investment income than you earned, and never on more MAGI overage than actually exists.

The computation happens on IRS Form 8960, which walks through the income categories, allowable deductions, and the comparison against your threshold. The result flows to Schedule 2 (Form 1040), line 12, and into your total tax.³

Passive vs. Active Business Income

Whether business income falls inside or outside the surtax turns on material participation. The IRS uses seven tests, and passing any one is enough. The most common is logging more than 500 hours in the activity during the tax year.⁵ Other tests include being the only person who participates, participating more than 100 hours when no one else logs more, or having materially participated in any five of the previous ten years.

Rental real estate has an extra wrinkle. Qualifying as a real estate professional for regular income tax purposes doesn’t automatically exempt rental income from this surtax. To claim the safe harbor here, you need more than 500 hours in each rental real estate activity during the year, or that same 500-hour threshold in any five of the preceding ten tax years. Poor documentation of those hours is a frequent audit trigger.

Ways to Reduce the Bill

Because the surtax depends on two variables, anything that lowers either your net investment income or your MAGI can shrink it.

Harvest Losses Against Gains

Selling investments at a loss offsets capital gains dollar for dollar, directly reducing net investment income. Losses beyond gains can offset up to $3,000 of ordinary income per year ($1,500 for married filing separately), with the rest carrying forward indefinitely. For a top-bracket taxpayer, a long-term capital gain effectively carries a combined federal rate of 23.8% once the surtax is layered on, so harvested losses deliver real savings.

Spread a Sale Across Years

A lump-sum sale of an appreciated asset can dump a large gain into one tax year and push MAGI well over the threshold. Structuring the sale as an installment arrangement lets you recognize the gain gradually, potentially keeping MAGI below the threshold in some years.

Maximize Pre-Tax Retirement Contributions

Contributions to a 401(k) or traditional IRA reduce AGI, and lower AGI means lower MAGI. For W-2 earners whose salary alone is bumping against the threshold, this is one of the most accessible levers.

Time Roth Conversions Around Other Income

A large Roth conversion in the same year you realize a big capital gain can create a double hit: the conversion pushes MAGI over the threshold, and the gain then sits fully in the taxable zone. Splitting conversions across lower-income years avoids the spike.

Consider Municipal Bonds

Interest from municipal bonds is excluded from both net investment income and MAGI.¹ Shifting part of a fixed-income portfolio into munis reduces both sides of the calculation. Muni yields are typically lower than taxable alternatives, so the trade only works when the tax savings outweigh the yield gap.

Trusts and Estates

Trusts and estates pay the same 3.8% rate, but the threshold is far lower. The tax applies once adjusted gross income exceeds the dollar amount at which the highest trust tax bracket begins, roughly $16,000 for 2026.¹ Even modest investment income retained inside a trust can trigger the surtax.

Only undistributed net investment income counts at the trust level. Income distributed to beneficiaries moves to their personal returns and is measured against their individual thresholds. Distributing investment income to beneficiaries in lower brackets can reduce or eliminate the trust-level surtax, at the cost of shifting the underlying income tax to the recipients.

Reporting, Estimated Payments, and Penalties

You report the tax on Form 8960 and carry the result to Schedule 2 (Form 1040), line 12.³ Payment goes through any standard IRS channel: Direct Pay, the Electronic Federal Tax Payment System, or a check with the return.⁶

If you expect to owe, factor the surtax into your quarterly estimated payments. The IRS penalizes underpayment unless you’ve paid at least 90% of the current year’s total tax or 100% of the prior year’s total tax through withholding and estimated payments, whichever is less. If your prior-year AGI exceeded $150,000 ($75,000 if married filing separately), the prior-year safe harbor rises to 110%.⁷ Taxpayers who cross the MAGI threshold for the first time are especially exposed, because their prior-year tax didn’t include the surtax and their withholding doesn’t account for it.

The failure-to-pay penalty runs at 0.5% of the unpaid balance per month, capped at 25%. Interest accrues separately, calculated at the federal short-term rate plus three percentage points and compounded daily.⁸

1
Internal Revenue Service. Topic No. 559, Net Investment Income Tax
2
Office of the Law Revision Counsel. 26 USC 1411 – Imposition of Tax
3
Internal Revenue Service. 2025 Instructions for Form 8960
4
Internal Revenue Service. Questions and Answers on the Net Investment Income Tax
5
Internal Revenue Service. Publication 925 (2025), Passive Activity and At-Risk Rules
6
Internal Revenue Service. Payments
7
Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty
8
Internal Revenue Service. Topic No. 653, IRS Notices and Bills, Penalties and Interest Charges