Tax Loss Harvesting: Turn Investment Losses Into Real Tax Savings

What Is Tax Loss Harvesting?

Tax loss harvesting is the practice of selling investments that have declined in value below your purchase price to realize a capital loss for tax purposes. That loss can then be used to offset capital gains from other investments or, if losses exceed gains, to reduce ordinary income by up to $3,000 per year. Any losses beyond what you can use this year carry forward to future tax years indefinitely.

The key insight is that the tax saving is immediate and real, even though you can reinvest in similar assets right away. Effectively, you are turning a paper loss into a tax benefit while maintaining roughly the same investment exposure.

How Capital Gains and Losses Work

When you sell an investment for more than you paid, you have a capital gain. When you sell for less, you have a capital loss. The tax treatment depends on how long you held the asset:

• Short-term capital gains: Assets held 12 months or less; taxed as ordinary income (up to 37%)
• Long-term capital gains: Assets held more than 12 months; taxed at 0%, 15%, or 20% depending on income

When you harvest losses, short-term losses first offset short-term gains (which are taxed at higher rates), and long-term losses first offset long-term gains. This netting process is handled automatically when you file Schedule D on your tax return.

A Step-by-Step Tax Loss Harvesting Example

Imagine it’s November and you review your taxable brokerage account:

• You sold an S&P 500 ETF earlier in the year for a $8,000 long-term capital gain
• You also hold a tech sector ETF currently worth $15,000, which you purchased for $20,000—a $5,000 unrealized loss

By selling the tech ETF before year-end, you realize a $5,000 capital loss. This offsets $5,000 of your $8,000 capital gain, leaving you with only $3,000 of net taxable gain. At a 15% long-term capital gains rate, you’ve saved $750 in taxes.

Immediately after selling, you buy a similar (but not identical) ETF—say, a broader technology index fund—to maintain your market exposure. Your portfolio allocation stays roughly the same, but you’ve locked in a valuable tax deduction.

The $3,000 Ordinary Income Deduction

If your total capital losses exceed your total capital gains, you can deduct up to $3,000 of the excess against ordinary income (wages, self-employment income, etc.) per year. For a person in the 22% bracket, that’s a $660 reduction in federal income taxes. For a couple in the 24% bracket, it’s $720.

Any losses beyond $3,000 that you cannot use this year carry forward to future years. There is no time limit on the carryforward. If you have $20,000 in capital losses and $5,000 in gains, you offset the gains completely and carry forward $12,000 in losses (after using $3,000 against ordinary income this year).

The Wash-Sale Rule: The Critical Constraint

The IRS has a rule specifically designed to prevent abuse of tax loss harvesting: the wash-sale rule. If you sell a security at a loss and buy a “substantially identical” security within 30 days before or after the sale, the loss is disallowed. The 30-day window applies in both directions—so the window is effectively 61 days total (30 days before through 30 days after).

What counts as substantially identical? The IRS hasn’t fully defined this, but clear examples include:

• Selling stock in Company X and buying it back within 30 days
• Selling an S&P 500 index fund and buying another S&P 500 index fund tracking the same index from a different provider

What is generally not considered substantially identical:

• Selling a total stock market ETF and buying an S&P 500 ETF
• Selling a Vanguard fund and buying a similar but different Fidelity fund that tracks a slightly different index
• Selling a stock and buying a similar company in the same industry

The wash-sale rule also applies across accounts. If you sell a stock at a loss in your taxable account and buy the same stock in your IRA within the window, the loss is still disallowed in the taxable account.

When Tax Loss Harvesting Makes the Most Sense

Tax loss harvesting is most valuable when:

• You have a taxable brokerage account (not retirement accounts, where gains and losses have no immediate tax impact)
• You have already realized capital gains in the current year that you want to offset
• You are in a high enough tax bracket that the savings are meaningful (22% or above)
• Markets have declined significantly, creating temporary losses in diversified funds
• You have a long investment time horizon and can maintain exposure while waiting out the wash-sale period

It is less valuable if you are in the 0% long-term capital gains bracket (taxable income under $47,025 for single filers in 2024) or if all your investments are in tax-advantaged retirement accounts.

Tax Loss Harvesting in Practice

You can do this manually by reviewing your taxable accounts for unrealized losses each fall, or you can use a robo-advisor like Betterment or Wealthfront that offers automated tax-loss harvesting—scanning your portfolio daily for opportunities. Automated services are especially useful for larger portfolios where the savings can be substantial.

When harvesting manually: review your taxable accounts in October or November; identify positions with meaningful unrealized losses; sell those positions and immediately reinvest in similar but not substantially identical alternatives; document the transactions for your tax records.

Long-Term Impact of Consistent Harvesting

Studies by Vanguard and others have estimated that disciplined tax-loss harvesting can add 0.1% to 1.8% per year to after-tax returns, depending on portfolio size and market volatility. Over a 30-year investing career, even a 0.5% annual improvement in after-tax returns on a $500,000 portfolio adds up to tens of thousands of dollars. It’s not free money—it’s a tax timing strategy—but the compounding benefit is real.