Can Tax-Loss Harvesting Reduce the 3.8% NIIT? (w/Examples) + FAQs

This article reflects federal rules as of June 2026 and covers tax years 2025 and 2026. The Net Investment Income Tax is a federal-only tax — no state has its own version. Tax law changes, so confirm current figures before you file. This guide is educational and is not a substitute for advice from a licensed CPA or tax attorney for your specific situation.

Quick Answer

Yes. For tax years 2025 and 2026, tax-loss harvesting can reduce the 3.8% Net Investment Income Tax. Selling losing investments offsets capital gains, which lowers your net investment income. Since the NIIT is 3.8% of the smaller of your net investment income or your income over the threshold, a smaller gain often means a smaller tax.

Why This Matters Right Now

If you have a taxable brokerage account and a high income, you may owe an extra 3.8% surtax on top of your regular capital gains tax. This surtax is the Net Investment Income Tax, often called the NIIT, and it quietly raises your bill the moment your income crosses a fixed line. The immediate consequence is real: a $50,000 long-term gain can cost you $1,900 in NIIT alone, separate from the regular 15% or 20% capital gains tax. Tax-loss harvesting — selling investments that have dropped in value to bank the loss — is one of the few tools that can shrink that surtax in the same year you trigger it.

The stakes climb every year because the income lines that trigger the NIIT have not moved since 2013. The thresholds are not indexed for inflation, so each year inflation and rising wages pull more middle-and-upper earners into the tax for the first time. According to the IRS, the surtax applies once your modified adjusted gross income clears $200,000 (single) or $250,000 (married filing jointly). If you sell appreciated assets, hold rental property, or earn large dividends, this article shows you exactly how harvesting losses changes your math.

• 💰 How harvesting losses cuts both your capital gains tax and your 3.8% NIIT in the same year.
• 📊 Three fully worked dollar examples so you can copy the math for your own return.
• ⚠️ The wash-sale trap that can erase your loss and the $3,000 limit that caps how much helps.
• 🧭 A decision aid to find which filing situation and income level actually applies to you.
• 📝 How to report it on Form 8960 and Form 8949, plus the December deadline you can’t miss.

What the 3.8% NIIT Actually Is

The Net Investment Income Tax is a 3.8% federal surtax created by the Affordable Care Act and codified in Internal Revenue Code Section 1411. It took effect in 2013 and is reported on Form 8960. The tax is not a tax on all your income. It is a tax on your investment income, but only after your total income crosses a set line.

Here is the rule in plain words. The IRS charges 3.8% on the smaller of two numbers: your net investment income, or the amount your modified adjusted gross income (MAGI) sits above your threshold. Because the tax hits the smaller of the two, both numbers matter, and lowering either one can lower the tax. Tax-loss harvesting attacks the first number — your net investment income.

The consequence of ignoring the NIIT is a surprise balance due. Many people plan only for the 15% or 20% capital gains rate and forget the surtax, then owe more than expected at filing. A common misconception is that the NIIT replaces capital gains tax. It does not. It stacks on top, which is why a high earner can face an effective 23.8% rate on long-term gains. What you should do is run the Form 8960 math before you sell, not after.

What Counts as Net Investment Income

Net investment income includes interest, dividends, capital gains, rental and royalty income, non-qualified annuities, and income from passive businesses. It does not include wages, self-employment income, Social Security, or distributions from retirement accounts like a 401(k) or IRA. The “net” part means you subtract related expenses, such as investment interest and certain advisory fees.

This matters because tax-loss harvesting only touches the capital-gains slice of this list. If your NIIT comes mostly from rental income or interest, selling a losing stock does little. A misconception here is that any loss helps; in truth, a capital loss first offsets capital gains, and only the net result flows into your investment income. What you should do is identify which type of investment income is driving your NIIT before you assume harvesting will fix it.

The Threshold That Never Moves

The MAGI thresholds are $200,000 for single and head of household, $250,000 for married filing jointly, and $125,000 for married filing separately. These figures have not changed since 2013 and are not adjusted for inflation. For tax year 2025, estates and trusts hit the NIIT at just $15,650 of undistributed income, per IRS Topic 559.

The consequence of the frozen threshold is “bracket creep.” A salary that was comfortably under the line in 2013 may now sit above it after a decade of raises. The misconception is that these numbers rise like the standard deduction does — they do not. What you should do is treat $200,000 or $250,000 as a hard, permanent wall and plan your sales around it.

How Tax-Loss Harvesting Reduces the NIIT

Tax-loss harvesting is selling an investment for less than you paid to lock in a capital loss. That loss offsets capital gains dollar for dollar. Because capital gains are part of net investment income, cutting your net gain directly cuts the income the NIIT is measured against.

There are two paths a loss can take, and they affect the NIIT differently. First, a capital loss offsets capital gains with no limit, which is the path that powers NIIT savings. Second, if losses exceed gains, you may deduct only $3,000 of net loss against ordinary income each year, and that ordinary-income piece does not reduce investment income at all. The rest carries forward to future years.

The key limit to understand is that harvesting reduces your net investment income, but it does not by itself push your MAGI back under the threshold. A capital loss only lowers MAGI by up to $3,000 in a loss year, because that is all that flows to ordinary income. So harvesting helps most when your investment income — not your wage income — is the smaller of the two NIIT numbers. The consequence of misunderstanding this is harvesting losses that don’t move your tax at all because your MAGI excess, not your investment income, was the binding number.

Worked Example: A Married Couple Cuts the Surtax

Meet David and Maria, married filing jointly, with $300,000 of MAGI for tax year 2025. They realized a $50,000 long-term capital gain from selling Stock A. Their MAGI threshold is $250,000.

Before harvesting, the NIIT is 3.8% of the smaller of their net investment income ($50,000) or their MAGI excess ($300,000 − $250,000 = $50,000). Both equal $50,000, so the NIIT is 3.8% × $50,000 = $1,900.

Now they harvest a $30,000 loss by selling Stock B, which dropped in value. Their net capital gain falls to $50,000 − $30,000 = $20,000. The loss also lowers their MAGI: $300,000 − $30,000 = $270,000, so the excess over the threshold is $20,000. The NIIT is now 3.8% of the smaller of $20,000 (net investment income) or $20,000 (MAGI excess) = 3.8% × $20,000 = $760.

Their NIIT drops from $1,900 to $760 — a $1,140 saving — and they also cut their regular long-term capital gains tax on that $30,000 of gain. This is the cleanest case: harvesting helped because their investment income and MAGI excess fell together.

Worked Example: When Harvesting Does Not Help

Meet Priya, a single filer with $400,000 of MAGI for tax year 2025, mostly wages. Her net investment income is just $20,000 from dividends and a small gain. Her threshold is $200,000.

Her NIIT is 3.8% of the smaller of $20,000 (net investment income) or $200,000 (MAGI excess of $400,000 − $200,000). The smaller number is $20,000, so her NIIT is $760.

Priya harvests a $15,000 capital loss. Her net investment income drops to $5,000. But here is the catch: a loss only reduces MAGI by up to $3,000, so her MAGI falls to about $397,000 and her excess is still about $197,000. The NIIT is now 3.8% of the smaller of $5,000 or $197,000, which is $190. She still saved $570, but notice the saving was capped by how little investment income she had. Harvesting beyond what offsets her actual gains gave her only a carryforward, not more NIIT relief this year.

Worked Example: The Wash-Sale Mistake

Meet Tom, single, with $260,000 MAGI for tax year 2026 and a $40,000 long-term gain. He sells a losing ETF on December 20 to harvest a $25,000 loss, then buys the same ETF back on December 28 because he still likes it.

The problem is the wash-sale rule. Because he repurchased a substantially identical security within 30 days, the IRS disallows his $25,000 loss for the year. His net investment income stays at $40,000, and his MAGI excess is $60,000, so his NIIT is 3.8% × $40,000 = $1,520 — exactly what it would have been if he had never sold. The disallowed loss is added to the new shares’ basis, so the benefit is only deferred, not gained this year. Tom waited 31 days the next time and kept his loss.

Which Situation Applies to You?

Your benefit from harvesting depends entirely on which NIIT number is smaller and where your income comes from. Use these branches to find yourself.

• Your investment income is smaller than your MAGI excess: Harvesting helps directly, because cutting net investment income cuts the very number the 3.8% applies to. This fits retirees and investors with large gains.
• Your MAGI excess is smaller than your investment income: Harvesting helps only up to $3,000 of MAGI relief per year, because a loss barely lowers MAGI. High-wage earners with modest gains fall here.
• You are just over the threshold: Even a small harvested loss can drop you under the line, erasing the NIIT entirely. This is the highest-value spot.
• You are far below the threshold: You owe no NIIT at all, so harvest only for regular capital gains reasons, not the surtax.
• Your income is mostly rental, interest, or passive business: Capital-loss harvesting does little; look at other strategies like grouping elections or retirement contributions instead.

Three Common Scenarios

These three patterns show up most often when investors try to cut the NIIT with harvested losses.

Investor Move	What Happens to the 3.8% NIIT
Harvest a loss equal to your realized gain, no repurchase	Net investment income and NIIT both fall sharply; cleanest saving
Harvest a loss but rebuy the same security within 30 days	Wash-sale rule disallows the loss; NIIT does not change this year
Harvest losses far above your gains	Only $3,000 reduces ordinary income; excess carries forward, limited NIIT help now

How to Report It on Your Tax Forms

You report each sale on Form 8949, then total the gains and losses on Schedule D of your Form 1040. The net capital gain that survives flows into your adjusted gross income. From there, you calculate the surtax on Form 8960 and carry the result to Schedule 2 of your Form 1040.

On Form 8960, your net gain or loss appears in the investment-income section near the top. The form then subtracts allowable expenses, applies your threshold, and multiplies the smaller figure by 3.8%. The deadline to realize a loss for a given tax year is December 31 of that year — the trade must settle in the calendar year. You file the forms with your return by April 15 of the following year, or by the extended October deadline if you file Form 4868. Keep your broker’s Form 1099-B and your purchase records for at least three years.

Deadlines, Costs, and Timing

The hard deadline for harvesting is the last trading day of the year, usually around December 29–31, because the loss must occur in the tax year you want it. Miss it, and the loss lands in the next year instead. The wash-sale clock runs 30 days before and after the sale, creating a 61-day window you must clear before rebuying.

Doing this yourself costs only trading commissions, which are often zero at major brokers. Hiring a CPA for year-end planning typically runs a few hundred to a couple thousand dollars, depending on portfolio size. Software-based “automated” harvesting from robo-advisors usually folds into a 0.25%–0.40% annual advisory fee. Call a professional when you have large gains, multiple accounts, or rental and passive income mixed in.

Mistakes to Avoid

Each of these errors carries a real cost, so review them before you place a single year-end trade.

• Triggering a wash sale. Rebuying the same or substantially identical security within 30 days disallows your loss, so your NIIT does not drop at all this year.
• Buying in your IRA. A repurchase in your IRA within 30 days also triggers the wash-sale rule, and the loss is lost permanently because IRA basis can’t be recovered.
• Assuming losses lower MAGI a lot. A net loss reduces MAGI by only $3,000 a year, so harvesting alone rarely pulls you under the threshold.
• Harvesting when you owe no NIIT. If your MAGI is below the threshold, you gain no surtax benefit and may waste a useful loss.
• Forgetting the $3,000 ordinary-income cap. Losses above your gains help ordinary income only $3,000 a year; the rest carries forward and gives no NIIT relief now.
• Missing the December 31 deadline. A trade that settles in January counts for the wrong year, leaving you with the full NIIT this year.
• Ignoring state tax differences. No state has a NIIT, but your state may still tax the underlying capital gain, so a loss can change your state bill too.

Do’s and Don’ts

These quick rules keep your harvesting clean and your loss deductible.

• Do match your harvested loss to your realized gains first, because that is where unlimited offset and the biggest NIIT savings live.
• Do wait 31 days before rebuying the same security, so the wash-sale rule cannot disallow your loss.
• Do buy a similar-but-not-identical fund to stay invested during the waiting period without triggering a wash sale.
• Do run your Form 8960 math both ways before selling, since the smaller of two numbers controls the tax.
• Do track carryforward losses, because they offset unlimited future gains and future NIIT.
• Don’t rebuy in any account, including your spouse’s or IRA, within the window, or you forfeit the loss.
• Don’t sell good long-term holdings just to harvest, because resetting basis can raise future gains.
• Don’t assume harvesting cuts MAGI, since only $3,000 of net loss reaches ordinary income.
• Don’t wait until December 31 to act, because settlement timing can push the trade into the next year.
• Don’t forget to report carryovers, or you may lose track of a valuable deduction.

Pros and Cons

Weigh both sides before you build a harvesting plan around the NIIT.

• Pro: It cuts both the 3.8% NIIT and your regular capital gains tax in the same year when losses offset gains.
• Pro: Capital losses offset capital gains with no dollar limit, so large gains can be fully neutralized.
• Pro: Unused losses carry forward forever, protecting future gains and future surtax.
• Pro: It is often free to do, with zero-commission trades at most brokers.
• Pro: It can drop a near-threshold filer under the line, erasing the NIIT entirely.
• Con: A loss reduces MAGI by only $3,000 a year, so it rarely solves a MAGI-driven NIIT alone.
• Con: The wash-sale rule can disallow the loss and waste the whole effort.
• Con: Selling resets your basis lower, which can mean bigger taxable gains later.
• Con: It does nothing if your NIIT comes mostly from rents, interest, or passive income.
• Con: Frequent harvesting adds recordkeeping and can disrupt your long-term allocation.

What to Do Next

Take these steps in order before the year ends to capture the most NIIT savings.

1. Estimate your tax-year MAGI and your total net investment income, then identify which is the smaller NIIT number.
2. List your taxable holdings that are currently below your purchase price and total the harvestable losses.
3. Match losses to your realized gains first, since that combination delivers the largest NIIT cut.
4. Sell the chosen positions by the last trading day of the year, and avoid rebuying anything identical for 31 days.
5. Gather your Form 1099-B and purchase records, then report sales on Form 8949 and the surtax on Form 8960.
6. Call a CPA or tax attorney if you have rental income, passive businesses, large gains, or trust income, where the math gets complex.

Frequently Asked Questions

Does tax-loss harvesting reduce the 3.8% NIIT? Yes. Harvested capital losses offset capital gains, lowering your net investment income for tax years 2025 and 2026. Since the NIIT taxes the smaller of net investment income or your MAGI excess, a smaller gain usually means a smaller surtax.

How much is the Net Investment Income Tax? 3.8%. The surtax equals 3.8% of the lesser of your net investment income or the amount your MAGI exceeds your threshold, for tax year 2025 and 2026. It stacks on top of regular capital gains tax.

What are the NIIT income thresholds for 2025? $250,000 / $200,000 / $125,000. For tax year 2025, the MAGI thresholds are $250,000 (married filing jointly), $200,000 (single or head of household), and $125,000 (married filing separately). They have not changed since 2013.

Are the NIIT thresholds indexed for inflation? No. The thresholds are fixed and have stayed the same since 2013, so rising income pulls more taxpayers into the NIIT each year. Plan around the unchanging $200,000 and $250,000 lines.

Does a capital loss lower my MAGI for NIIT purposes? Only up to $3,000. A net capital loss reduces ordinary income, and therefore MAGI, by no more than $3,000 per year. The rest offsets capital gains or carries forward but does not cut MAGI further.

What is the wash-sale rule? A 61-day repurchase ban. If you buy the same or substantially identical security within 30 days before or after selling at a loss, the IRS disallows the loss. The disallowed amount adds to the new shares’ basis.

Can I harvest losses in December and rebuy in January? No, not the same security. A December 31 sale and January 1 repurchase still fall inside the 30-day window and trigger the wash-sale rule. Wait at least 31 days or buy a similar, non-identical fund.

Which form reports the NIIT? Form 8960. You calculate the 3.8% surtax on Form 8960, then carry it to Schedule 2 of your Form 1040. Individual sales are first reported on Form 8949 and Schedule D.

Do states have their own NIIT? No. The Net Investment Income Tax is purely federal under IRC Section 1411. No state imposes a matching surtax, though your state may still tax the underlying capital gains at its own rates.

What happens to losses bigger than my gains? They carry forward. Up to $3,000 of net loss offsets ordinary income each year, and the rest carries forward indefinitely to offset future gains and future NIIT, with no expiration date.

Does harvesting help if my NIIT comes from rental income? No, very little. Capital-loss harvesting offsets capital gains, not rental or interest income. If rents drive your net investment income, look at passive-activity grouping or retirement contributions instead.

Can retirement account trades trigger the NIIT? No. Sales inside a 401(k) or IRA are not investment income for NIIT, and distributions are excluded from MAGI in the year taken. But large distributions can raise MAGI and indirectly affect the NIIT on other income.