How Does Tax-Loss Harvesting Actually Work, and Who Benefits Most?
By Lotus Asset Management
At Lotus Asset Management, we work mostly with high earners, and for a lot of them a long-term capital gain is not taxed at 15% at all. Once your income clears a certain line, the real federal rate on those gains is 18.8%, and for the highest earners it is 23.8%. That gap, the one between the rate people assume they pay and the rate they actually pay, is where tax-loss harvesting earns its keep.
Tax-loss harvesting is the practice of selling an investment that is worth less than you paid for it, using that loss to offset capital gains and a limited amount of ordinary income, then reinvesting the proceeds so your market exposure stays intact. The loss becomes real for tax purposes. Your investment plan does not skip a beat.
It sounds like an accounting trick. It is closer to basic maintenance, and the fourth quarter is when it matters most, because your realized gains for the year are mostly known by now and there is still time to do something about them. Here is how the mechanics work, the one rule that trips people up, why the strategy matters more once your income crosses certain thresholds, and when it is not worth the effort.
What Does Tax-Loss Harvesting Do to Your Tax Bill?
A harvested loss first cancels out capital gains of the same type, and anything left over can reduce up to $3,000 of ordinary income per year.
The netting follows a specific order. Short-term losses offset short-term gains first, long-term losses offset long-term gains first, and then any remaining loss of one type crosses over to offset net gains of the other type. If your losses still exceed all of your gains after that, you can deduct up to 3,000againstordinaryincome(1,500 if you file married filing separately). Whatever is still left does not disappear. It carries forward indefinitely, available to offset gains in future years or to chip away at ordinary income $3,000 at a time.
That carryforward is the quietly valuable part. A large loss harvested in a volatile year can shelter gains for years afterward, including the gain you eventually realize when you sell a position you have held for a long time. At Lotus, we track these carryforwards as a running asset, because someone who harvested during a down stretch is often sitting on losses they have forgotten they own.
One distinction worth keeping straight: short-term gains (ie. on assets held one year or less) are taxed at your ordinary income rate, which for a high earner can be far higher than any long-term rate. Using losses to neutralize a short-term gain is often the most valuable harvest of all.
What Is the Wash-Sale Rule, and How Do You Avoid Tripping It?
The wash-sale rule disallows your loss if you buy the same or a "substantially identical" security within 30 days before or after the sale, which means you have a 61-day window to be careful about.
This is the rule that catches people, usually by accident. If you sell a fund at a loss on December 10 and your automatic dividend reinvestment buys a few shares of that same fund on December 20, part of your loss is disallowed. The disallowed amount is not lost forever; it gets added to the cost basis of the replacement shares. But the deduction you were counting on for this year evaporates. The rule also reaches across accounts, so a repurchase in your IRA or your spouse's account can trigger it just as easily as one in the account where you sold.
The workaround is straightforward. Sell the losing position and immediately reinvest in something that gives you similar market exposure without being substantially identical, for example a broad index fund from a different provider that tracks a different underlying index. You stay invested, your allocation does not drift, and your loss stays deductible. After the 61-day window closes, you can move back to the original holding if you want to. Turning off automatic reinvestment in the weeks around a harvest is one of the few things we cannot do on your behalf, and it is worth a two-minute check.
Why Does This Matter More Once You Cross the NIIT Threshold?
Because the net investment income tax adds a 3.8% surtax on investment income once your modified adjusted gross income passes $200,000 (single) or $250,000 (married filing jointly), and a harvested loss reduces the income that surtax applies to.
The net investment income tax is a 3.8% charge on investment income, including capital gains, dividends, interest, and rental income, that sits on top of your regular capital gains rate. These thresholds are set by statute and are not adjusted for inflation, so more high earners drift over them every year. Practically, it means a long-term gain that you assumed would be taxed at 15% is actually taxed at 18.8%, and a gain taxed at the top 20% long-term rate (which in 2026 starts above $545,500 of taxable income for single filers and $613,700 for joint filers) is really taxed at 23.8%. Every dollar of gain you offset with a harvested loss is a dollar that avoids both the capital gains rate and the 3.8% surtax. For someone well over the line, the combined saving can be meaningful on a large position.
What Does This Look Like in Practice?
Consider Ella, a physician who files jointly with about $480,000 in taxable income for 2026. Earlier in the year she rebalanced a taxable brokerage account and realized $40,000 of long-term gains. She also owns an international stock fund that is worth $25,000 less than she paid for it.
If she sells the international fund, she realizes a $25,000 long-term loss that offsets $25,000 of her $40,000 gain, leaving only $15,000 taxable. Because her income puts her in the 15% long-term bracket and above the net investment income tax threshold, her effective rate on those gains is 18.8%. Offsetting $25,000 of gain at 18.8% lowers her tax by roughly $4,700 for the year. She then reinvests the proceeds in a different international fund that tracks a different index, so her portfolio keeps the same exposure and she steers clear of the wash-sale rule. If her loss had been larger than all of her gains, she could have used up to $3,000 of the excess against her ordinary income and carried the rest forward. The number is specific to Ella's income, her gains, and her timing, and a different set of facts produces a different result.
When Is Tax-Loss Harvesting Not Worth It?
Harvesting does little or nothing when you have no gains to offset, when your income is low enough that your long-term gains are already taxed at 0%, or when the position is held in a tax-advantaged account.
A few conditions matter here. Losses inside a 401(k), IRA, or other tax-deferred account cannot be harvested, because gains and losses in those accounts do not hit your tax return. If your 2026 taxable income lands below the 0% long-term bracket (up to $98,900 for joint filers), you may be paying nothing on long-term gains already, which makes harvesting against them pointless. It is also worth remembering that harvesting lowers your cost basis in the replacement investment, so part of what you are doing is deferring tax to a future sale rather than erasing it. That still has real value through the time you keep the money invested, but it is not the same as a permanent saving. The strategy rewards households with taxable accounts, realized gains, and enough income for the rate difference to matter. It does less for everyone else.
The Takeaway
Tax-loss harvesting is one of the few moves that can lower a tax bill you have already generated, without changing how you are invested. The two things to get right are the timing, since the window closes on December 31, and the wash-sale rule, since one careless repurchase can undo the whole exercise. The carryforward turns a bad year for a given position into a credit you can use for years.
If you rebalanced, sold a property, exercised equity, or took gains anywhere in a taxable account this year, it is worth looking at what else in that account is underwater before the calendar runs out. If any of this applies to your situation, it is worth a conversation with your advisor before year-end.
Frequently Asked Questions
Q: Does tax-loss harvesting actually save me money, or does it just delay the tax?
A: It can do either, depending on the situation. When a harvested loss offsets a gain you would otherwise pay tax on this year, that is a real reduction for the year. Because harvesting also lowers your cost basis in the investment you buy to replace the one you sold, some of the benefit can be a deferral of tax to a later sale rather than a permanent saving. Both outcomes have value, but they are not the same thing.
Q: Can I sell a stock at a loss and buy it right back?
A: Not if you want to keep the deduction. The wash-sale rule disallows the loss if you buy the same or a substantially identical security within 30 days before or after the sale, a 61-day window in total, and it applies across your IRA and your spouse's accounts too. The common fix is to reinvest the proceeds in a similar but not identical investment so you stay in the market without tripping the rule.
Q: I only have gains this year and no losing positions. Is there anything to harvest?
A: If nothing in your taxable accounts is worth less than you paid, there is nothing to harvest this year, and that is fine. It is still worth checking, because a position can be down even in a year when the broad market is up, and any losses you do not need this year carry forward to offset gains later. Harvesting applies only to taxable accounts, so losses inside retirement accounts do not count.
