Tax-Loss Harvesting: How Selling Losers Can Lower Your Tax Bill

Selling investments at a loss feels terrible. Nobody opens a brokerage app hoping to see red. But here's the counterintuitive truth: those losses have real monetary value. A $10,000 investment loss can save you $1,500 to $3,700 in taxes, depending on your bracket.

Tax-loss harvesting is the strategy of deliberately selling losing investments to offset gains and reduce your tax bill. Academic research using data from 1926 to 2018 estimates this approach can add approximately 1.1% per year to after-tax returns. Wealthfront's data suggests automated harvesting generates 0.78% to 1.38% in annual "tax alpha" for its clients.

Those numbers compound. On a $500,000 portfolio, 1% per year is $5,000 in tax savings. Over 20 years, that's six figures.

The quick version: Sell losing investments to offset capital gains and deduct up to $3,000 of ordinary income per year. Unused losses carry forward indefinitely. But you must avoid the wash-sale rule (no buying back the same security within 30 days).

How Tax-Loss Harvesting Works

The IRS lets you use capital losses to offset capital gains, dollar for dollar. If you have $8,000 in gains and $5,000 in losses this year, you only pay tax on the net $3,000.

If losses exceed gains, you can deduct up to $3,000 of the excess against ordinary income ($1,500 if married filing separately). Any remaining losses carry forward to future years. Indefinitely.

The sequence matters:

1. Short-term losses offset short-term gains first
2. Long-term losses offset long-term gains first
3. Any remaining net losses cross over to offset the other category
4. Net losses above capital gains offset up to $3,000 of ordinary income
5. Everything beyond that carries forward

Worked Example: The Tax Savings in Real Dollars

Profile: Danielle, 38, single filer. Salary: $160,000. 24% marginal tax bracket.

Portfolio activity this year:

• Realized short-term capital gains: $4,000 (from selling a tech stock held 6 months)
• Realized long-term capital gains: $0
• Unrealized loss on a different tech position: $10,000 (purchased for $15,000, now worth $5,000)

The harvest:

Danielle sells the losing position for $5,000, locking in a $10,000 short-term capital loss.

Tax impact:

Danielle still has $5,000 in cash from selling the position, plus $1,680 in tax savings. And she has three grand in losses banked for next year.

The reinvestment step matters too. Danielle can immediately invest that $5,000 into a similar (but not "substantially identical") investment to stay in the market. More on that in a moment.

The Wash-Sale Rule: The One Rule You Can't Break

Here's where tax-loss harvesting gets tricky. The IRS has a rule designed to stop investors from selling for a loss and immediately buying back the same thing:

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 runs in both directions. Sell on December 15? You can't have bought the same thing after November 14, and you can't buy it again before January 15. That's a 61-day total window.

What counts as "substantially identical"? The IRS hasn't published a precise definition, but here's the practical spectrum:

• Clearly a wash sale: Selling Vanguard S&P 500 ETF (VOO) and buying it back the next day
• Probably a wash sale: Selling VOO and buying iShares Core S&P 500 ETF (IVV). Both track the exact same index.
• Probably safe: Selling VOO and buying Vanguard Total Stock Market ETF (VTI). VTI tracks a different, broader index.
• Definitely safe: Selling VOO and buying a totally different asset class like bonds or international stocks

I've seen people get burned by the second category more than any other. "Different fund company, same index" is not different enough.

The penalty for violating the wash-sale rule isn't permanent destruction of the loss. The disallowed loss gets added to the cost basis of the new purchase. You'll eventually get the benefit, just not right now. But the timing difference matters for tax planning.

One more trap: the wash-sale rule applies across accounts. Sell a stock for a loss in your taxable brokerage, then buy it in your IRA within 30 days? That's a wash sale. And in this case, you may permanently lose the deduction because the IRA basis adjustment has no tax benefit.

Does the Wash-Sale Rule Apply to Crypto?

As of early 2026, cryptocurrency is classified as property, not a security. The wash-sale rule technically applies only to securities. This means you could, in theory, sell Bitcoin at a loss on Coinbase and buy it back immediately without triggering a wash sale.

Multiple budget proposals have targeted this loophole, and the IRS's "economic substance doctrine" could challenge purely tax-motivated transactions. The safest approach: assume the rules may change and don't rely on this gap as a permanent strategy.

When Tax-Loss Harvesting Makes Sense (and When It Doesn't)

Good candidates:

• You have realized gains elsewhere in your portfolio this year
• You're in a high tax bracket (24% or above)
• You can reinvest in a similar-but-not-identical fund to maintain your market exposure
• You're doing this in a taxable brokerage account

Not a good fit:

• You're in the 0% or 12% tax bracket (the tax savings are minimal)
• The losing investment is in a tax-advantaged account (IRAs, 401(k)s don't generate deductible losses)
• You'd have to dramatically change your portfolio allocation to avoid the wash-sale rule
• Transaction costs eat up the tax savings

Here's the fundamental principle: don't let the tax tail wag the investment dog. Harvesting a loss on an investment you'd sell anyway? Great. Selling a solid long-term holding just to claim a temporary loss? That's likely to cost you more in missed gains than you save in taxes.

Automated vs. Manual Harvesting

Robo-advisors like Wealthfront, Betterment, and Schwab Intelligent Portfolios offer automated tax-loss harvesting. They scan your portfolio daily and execute harvests whenever losses exceed a threshold.

Wealthfront's data shows that for 96% of taxable accounts using automated harvesting for at least a year, the estimated tax benefit exceeded the advisory fees paid. That's a strong argument for automation, especially if you wouldn't otherwise think to check for harvesting opportunities on a random Tuesday in October.

Manual harvesting works too. Review your portfolio quarterly (or at least in November before year-end). Identify positions with unrealized losses. Decide if selling makes sense given your overall gains for the year.

Your Next Move

1. Review your unrealized losses. Log into Fidelity, Schwab, or your brokerage and sort positions by gain/loss. Identify anything down 10% or more.
2. Calculate your net gains. Add up all realized gains and losses for the year so far. If you have net gains, harvesting losses can directly reduce your tax bill.
3. Pick your replacement investment. Before selling, identify a similar (not identical) fund to buy immediately. You want to maintain market exposure while avoiding the wash-sale window.
4. Set a calendar reminder. Mark the 31st day after any harvest. That's when you can buy back the original security if you prefer it over the replacement.
5. Consider a robo-advisor. If your portfolio is large enough, automated harvesting at Wealthfront or Betterment may generate more savings than the fees cost.

For the broader context on how capital gains tax works, start with our pillar guide. If you're looking at year-end timing, our year-end tax moves guide includes harvesting as part of a larger December strategy. And for investors who want to understand how long-term rates affect the savings calculation, that guide has every bracket.

References

1. Chaudhuri, S., Burnham, T., & Lo, A. (2020). An Empirical Evaluation of Tax-Loss-Harvesting Alpha. Financial Analysts Journal. https://rpc.cfainstitute.org/research/financial-analysts-journal/2020/empirical-evaluation-tax-loss-harvesting-alpha
2. Wealthfront. (2025). Wealthfront's Tax-Loss Harvesting White Paper. Wealthfront Research. https://research.wealthfront.com/whitepapers/tax-loss-harvesting/
3. Internal Revenue Service. (2025). Topic No. 409 Capital Gains and Losses. IRS.gov. https://www.irs.gov/taxtopics/tc409
4. Internal Revenue Service. (2024). Publication 550: Investment Income and Expenses. IRS.gov. https://www.irs.gov/forms-pubs/about-publication-550
5. Schwab Center for Financial Research. (2024). A Primer on Wash Sales. Schwab.com. https://www.schwab.com/learn/story/primer-on-wash-sales
6. TurboTax. (2026). Wash Sale Rule: What Is It, How Does It Work, and More. Intuit. https://turbotax.intuit.com/tax-tips/investments-and-taxes/wash-sale-rule-what-is-it-how-does-it-work-and-more/c5ANd7xnJ
7. CoinLedger. (2025). Crypto Wash Sale Rule. CoinLedger.io. https://coinledger.io/blog/crypto-wash-sale-rule