Tax-Loss Harvesting Explained

Every investor hates losing money. But there's a silver lining to investment losses that most people overlook: you can use them to reduce your tax bill. This strategy — called tax-loss harvesting — involves selling investments that are currently at a loss, using that loss to offset capital gains or up to $3,000 of ordinary income per year, and then reinvesting in a similar (but not identical) investment to maintain your market exposure. You end up in essentially the same position in the market but with a lower tax bill. The IRS is effectively giving you a discount on your losses. Over a lifetime of investing, tax-loss harvesting can add tens or even hundreds of thousands of dollars to your after-tax wealth.

How Tax-Loss Harvesting Works

The mechanics are straightforward. Suppose you bought an S&P 500 index fund for $50,000 and it's now worth $40,000 — a $10,000 unrealized loss. You sell the fund, realizing the $10,000 loss. Then you immediately buy a different but similar fund — say, a total stock market index fund — to maintain your stock market exposure. You haven't changed your investment strategy. You've just booked a tax loss.

That $10,000 loss can be used in three ways. First, it offsets capital gains dollar for dollar. If you sold another investment for a $10,000 gain, the loss cancels the gain — zero tax. Second, if you have no gains (or your losses exceed your gains), up to $3,000 of the loss can be deducted from your ordinary income per year. If you're in the 24% tax bracket, that $3,000 deduction saves you $720 in taxes. Third, any remaining losses carry forward indefinitely. A $50,000 loss this year can offset gains and income for many years into the future.

The critical rule is the wash-sale rule: you cannot buy a "substantially identical" security within 30 days before or after the sale. If you sell the Vanguard S&P 500 fund (VOO) at a loss, you can't buy it back within 30 days — the IRS will disallow the loss. But you can immediately buy the Schwab S&P 500 fund (SCHX) or a total market fund (VTI), which are similar enough to maintain your market exposure but different enough to avoid the wash-sale rule.

Tax-loss harvesting is most valuable in taxable brokerage accounts. It doesn't apply to tax-advantaged accounts like 401(k)s and IRAs because gains and losses in those accounts aren't taxed currently.

Why It Matters for Investors

Wealthfront, a robo-advisor that automates tax-loss harvesting, published data showing that their automated harvesting added 1.0-1.8% per year to clients' after-tax returns over a 10-year period. On a $500,000 portfolio, that's $5,000-$9,000 per year in tax savings — real money that stays invested and compounds over time.

The power of tax-loss harvesting is that it doesn't change your investment exposure or strategy. You're not selling stocks to go to cash. You're swapping one fund for a nearly identical one and collecting a tax benefit along the way. It's one of the few genuinely free lunches in investing.

The long-term compounding effect is significant. Every dollar saved in taxes stays invested, earning returns that compound for years. A $5,000 annual tax savings, invested at 10% for 20 years, grows to approximately $315,000. That's the cumulative value of a consistent tax-loss harvesting practice.

Bear markets and corrections are the prime harvesting season. When the market drops significantly, nearly every position in your taxable account will have unrealized losses available for harvest. Investors who harvested losses during the COVID crash in March 2020 or the 2022 bear market captured significant tax benefits while maintaining full market exposure throughout the recovery.

Real Example

An investor has a taxable brokerage account with three positions: a total stock market fund up $30,000, an international fund down $15,000, and a bond fund down $5,000. Without harvesting, if they sell the winning stock fund, they owe capital gains tax on $30,000 — roughly $4,500 at the 15% long-term rate. With harvesting, they sell the international fund and bond fund, realizing $20,000 in losses. They immediately reinvest in similar (but not identical) international and bond funds. Now when they sell the stock fund for a $30,000 gain, they offset it with $20,000 in harvested losses and owe tax on only $10,000 — roughly $1,500. They saved $3,000 in taxes, maintained their exact market exposure, and the $3,000 stays invested and compounding. Repeat this practice every year for 30 years, and the cumulative impact is a significantly larger after-tax portfolio.