What Is Tax-Loss Harvesting and How Does It Save You Money?

Tax-loss harvesting is one of the most powerful — and underused — strategies available to investors with taxable brokerage accounts. The concept is straightforward: when an investment in your portfolio has declined in value below what you paid for it, you sell it to "realize" the loss. That realized loss can then be used to offset capital gains from other investments you sold at a profit during the same tax year.

For example, if you sold Stock A for a $5,000 profit and Stock B for a $3,000 loss, you only owe capital gains tax on the net $2,000 gain. If your losses exceed your gains, you can deduct up to $3,000 of excess losses against ordinary income per year, and carry any remaining losses forward to future years indefinitely.

This strategy only works in taxable accounts — not in IRAs, 401(k)s, or other tax-advantaged retirement accounts where gains and losses have no immediate tax impact. The key insight is that you are not abandoning your investment thesis: after selling at a loss, you can immediately reinvest in a similar (but not "substantially identical") asset to maintain your market exposure.

The wash-sale rule is the most important constraint on tax-loss harvesting. It creates a 61-day window — 30 days before the sale, the sale date itself, and 30 days after — during which you cannot purchase a substantially identical security. If you do, the IRS disallows the loss.

What counts as "substantially identical" is not precisely defined, but the IRS has provided guidance through rulings:

• Selling Vanguard S&P 500 ETF (VOO) and buying iShares S&P 500 ETF (IVV) within 30 days is risky — they track the same index.
• Selling VOO and buying a total stock market fund like VTI is generally considered acceptable because VTI tracks a different, broader index.
• Selling shares of Apple stock and buying an Apple call option is substantially identical.
• Selling an S&P 500 index fund and buying an actively managed large-cap fund is generally not substantially identical.

The safest approach is to swap into a fund that provides similar market exposure but tracks a different index or uses a different investment methodology. Many investors swap between S&P 500 funds and total market funds, or between similar bond funds from different providers.

The value of tax-loss harvesting depends on several factors: your tax bracket, portfolio size, market volatility, and how long you maintain the strategy. Research from Wealthfront suggests the strategy adds approximately 1.0–1.5% annually in after-tax returns for typical investors.

Here is a concrete example:

• Portfolio value: $500,000 in a taxable brokerage account
• Realized gains for the year: $20,000
• Harvested losses: $15,000
• Net taxable gain: $5,000
• Tax bracket: 24% federal + 5% state = 29% combined
• Tax saved: $15,000 × 29% = $4,350

Over a 20-year investing career, consistent tax-loss harvesting can compound into significant additional wealth. At 1% annual tax alpha on a $500,000 portfolio growing at 8%, the strategy could add over $150,000 to your after-tax returns over two decades.

The strategy is most valuable during years of high market volatility (creating more loss-harvesting opportunities), when you have substantial realized gains to offset, and when you are in a high tax bracket. It becomes less valuable in retirement when you may be in a lower bracket.

While tax-loss harvesting is powerful, it is not appropriate for everyone:

1. Low tax bracket: If you are in the 0% long-term capital gains bracket (taxable income under $47,025 for single filers in 2026), harvesting losses provides little benefit since your gains are already tax-free.

2. Tax-advantaged accounts only: If all your investments are in IRAs, 401(k)s, or Roth accounts, there are no capital gains taxes to offset.

3. Small portfolio: The administrative complexity and potential for wash-sale violations may not justify the tax savings on portfolios under $50,000.

4. Concentrated positions: If you are harvesting losses on a stock you are emotionally attached to and want to repurchase, the 30-day waiting period creates real opportunity risk.

5. State tax considerations: Some states do not allow capital loss deductions or have different rules.

Also remember that tax-loss harvesting is a tax *deferral* strategy, not tax *elimination*. When you reinvest at a lower cost basis, your future gains will be larger. However, deferring taxes has genuine economic value because you can invest the tax savings and earn compound returns on money you would have otherwise paid to the IRS.

Step 1: Identify candidates. Review your taxable account for positions that have declined below your cost basis. Focus on losses of $1,000 or more to make the effort worthwhile.

Step 2: Check for wash-sale conflicts. Ensure you have not purchased the same security in the past 30 days and will not purchase it in the next 30 days — including in other accounts, your spouse's accounts, or through automatic dividend reinvestment.

Step 3: Sell the losing position. Execute the sale and note the realized loss amount.

Step 4: Reinvest immediately. Buy a similar but not substantially identical fund to maintain your asset allocation. Common swaps include:

• S&P 500 → Total Stock Market
• International Developed → International All-Cap
• US Aggregate Bond → Total Bond Market

Step 5: Set a 31-day calendar reminder. After 31 days, you can swap back to your original fund if preferred.

Step 6: Record everything. Track the sale date, loss amount, replacement security, and repurchase date. Your broker's 1099-B will report the loss, but you are responsible for tracking wash-sale compliance across accounts.

Many robo-advisors like Wealthfront, Betterment, and Schwab Intelligent Portfolios automate this entire process, making it accessible even to hands-off investors.