What Is Tax-Loss Harvesting & Are You Leaving Money On The Table

In December 2022, the markets spent the entire year getting worked. The S&P 500 was down roughly 20%. Bonds, the supposedly boring, safe part of the portfolio, were down even more. It was the kind of year that made people question their allocation, their advisor, and most of their recent choices.

Buried in the carnage was an opportunity. Not the "buy the dip" kind that finance Twitter was yelling about. Something more specific and more reliably valuable than any market call. Investors who knew what they were doing spent the last weeks of 2022 harvesting their losses, turning paper pain into bankable tax savings that would reduce what they owed the IRS for years afterward.

Investors who didn't know just suffered. That gap between people who know this tool exists and people who don't costs ordinary investors thousands of dollars a year in taxes they never had to pay.

When you sell an investment at a loss, the IRS lets you use that loss to offset gains elsewhere in your portfolio. Sell a winning stock and owe capital gains tax? A harvested loss can cancel some or all of it. If your losses exceed your gains, you can use up to $3,000 of the excess to offset ordinary income, which is the salary and bonus money taxed at your highest rate. Anything beyond that rolls forward into future tax years, sitting there like ammunition you stockpiled during the bad market.

The critical word is realized. The loss only becomes useful when you sell. A position sitting at a loss is a complaint, not a strategy. The moment you sell, you've converted an unrealized disappointment into a tangible tax asset you can actually use.

This is the step most investors skip. They see the loss, feel the pain, and hold on hoping for a recovery. The recovery may come, but in the meantime they've left a usable tax benefit untouched. You don't have to believe the position is dead forever to harvest the loss. You just have to sell it, capture the tax benefit, and immediately reinvest in something similar so you stay in the market.

The IRS does not care that you're sad your stock is down. It will let you use that sadness as a deduction.

The IRS anticipated that people would sell a losing position purely for the tax benefit and immediately buy it back. So it wrote the wash-sale rule. If you sell a security at a loss and buy the same or a "substantially identical" security within 30 days before or after the sale, the loss is disallowed. The IRS takes it back.

Thirty days on either side. Most investors learn this rule by violating it once.

The workaround is to sell the losing position and immediately buy something similar but not identical. Sell an S&P 500 index fund at a loss, buy a total market index fund that tracks a different index. You stay invested, which matters, because the real risk of tax-loss harvesting is sitting in cash during a recovery while you preserve the loss. After 31 days, you can swap back to your original holding if you want.

The distinction between "substantially identical" and "similar" is where advisors earn their fees and DIY investors make expensive mistakes. Two funds that track the same index are substantially identical. Two funds that both hold large-cap US stocks but track different indexes are usually fine. When in doubt, ask a tax professional before you sell.

The traps run deeper than most investors realize. Selling at a loss in your taxable brokerage and repurchasing the same security in your IRA within 30 days still triggers the rule. The IRS looks across your accounts, not just within one. Your spouse buying the same security inside that window counts too. If you have automatic dividend reinvestment turned on, those reinvested dividends can inadvertently trigger a wash sale on a position you just harvested. Turn off DRIP on positions you're actively harvesting.

There is one exception, and it currently sits in a category of its own. Cryptocurrency. As of today, the wash-sale rule does not apply to crypto. Bitcoin, Ethereum, and other digital assets are classified as property under current IRS rules, not securities. You can sell crypto at a loss, immediately buy it back, and still claim the deduction. No 30-day waiting period. No scramble for a similar-but-not-identical substitute. It is a legal and significant advantage active crypto holders should be using systematically. Whether this loophole survives future legislation is an open question. Use it while it exists.

Abstract tax concepts are easy to ignore. Specific numbers are harder.

Say you have $20,000 in gains from selling appreciated stock this year. At the long-term capital gains rate of 15%, that's a $3,000 tax bill sitting on your desk. You also have a position, a sector ETF you bought during a moment of misplaced enthusiasm, sitting at a $20,000 loss.

Sell the ETF. Your $20,000 gain is now offset by your $20,000 loss. Tax bill: zero.

If you're in the 20% capital gains bracket (household income above roughly $600,000 for married filers in 2025), the math gets more compelling. High earners also pay the 3.8% Net Investment Income Tax on top of capital gains. At that income level, tax-loss harvesting is a serious wealth preservation strategy that can save five figures in a single year.

Remember the $3,000 ordinary income offset. If you have excess losses beyond your gains, that $3,000 hits your regular income, which is taxed at your highest marginal rate. For someone in the 32% bracket, that's $960 back in your pocket every year you have excess losses to carry forward.

Tax-loss harvesting works under specific conditions. It is not a universal prescription.

It works when you hold investments in taxable brokerage accounts with meaningful unrealized losses, you have capital gains elsewhere to offset (this year or anticipated in future years), you sit in a tax bracket where capital gains are taxed at 15% or higher, and you have the discipline to stay invested rather than sitting in cash through the process.

It doesn't help when everything you own sits inside an IRA or 401(k). Losses inside tax-advantaged accounts carry no tax benefit because there is no mechanism to harvest them. The strategy lives in taxable accounts. If your portfolio is entirely in retirement accounts, this tool does not apply to you yet.

It actively backfires when you harvest losses and then sit in cash during a recovery, converting a paper loss into a real one. Or when you trigger the wash-sale rule by repurchasing too quickly. Or when you do it in a year where you have no gains and limited ordinary income to offset, generating losses you won't use for years.

Year-end is when most advisors run a systematic review. Large losses in volatile markets like 2022 warrant a look at any time of year.

The immediate tax savings are real. The compounding effect is where the strategy becomes powerful.

When you harvest a loss and reduce your tax bill, the money that would have gone to the IRS stays invested. That capital, earning market returns over years and decades, is the actual prize.

Tax-loss harvesting is not about avoiding taxes forever. When you eventually sell the replacement investment at a gain, you'll owe taxes on those gains. The strategy defers the bill and keeps more money compounding in the meantime. Think of it as an interest-free loan from the IRS. They will eventually get their money. You get to invest it until then.

Across long horizons, systematic tax-loss harvesting can add roughly 0.5% to 1.5% per year in after-tax returns, depending on market volatility and the investor's tax situation. In a year like 2022, the benefit runs higher. In a calm, steadily rising market, lower. Over a 30-year investing horizon, that annual increment compounds into a number that will make you furious you didn't start earlier.

Are you leaving money on the table? Maybe.

Log into your taxable brokerage account. Look at your unrealized gains and losses. If you have positions sitting at meaningful losses, and you have gains this year or expect them in the future, you have a conversation worth having with a tax advisor or financial planner before December 31.

If you use a robo-advisor, check whether automated tax-loss harvesting is included. Betterment, Wealthfront, and others run this systematically on your behalf. It's one of the legitimate value-adds of the robo model. If you're a DIY investor, this is a manual review, ideally done with a CPA who understands investment taxation.

If you have a financial advisor who has never mentioned tax-loss harvesting to you, ask why. The answer will tell you something about how they're managing your money.

The deeper question is whether your advisor can see the full picture. A broker managing only your brokerage account can't tell you that the loss you're sitting on there could offset the gain you just triggered in a different account elsewhere. An advisor with visibility into your entire financial life can spot those connections and act on them. The best tax-loss harvesting decisions are rarely made inside a single account. They are made across all of them at once.

The IRS built this into the tax code. It is not a loophole or aggressive tax planning. It is the system working as designed, rewarding investors who pay attention with a bill smaller than it had to be.