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Tax-loss harvesting is one of the highest-value tax planning tools available to taxable investors — it converts an inevitable short-term loss into a durable tax asset without requiring permanent exit from market exposure.
This guide explains tax-loss harvesting — how it works mechanically, the wash-sale rule, how to harvest losses without losing market exposure, when harvesting is most valuable, and the most common mistakes that eliminate the benefit.
Last updated: 2026-05-17
Tax-loss harvesting means deliberately selling positions at a loss to realize capital losses that offset capital gains — reducing your tax bill without permanently exiting market exposure by immediately reinvesting in a similar (but not identical) security.
Tax-loss harvesting is the practice of selling an investment at a loss to generate a capital loss deduction, then immediately reinvesting proceeds in a similar (but not identical) security to maintain market exposure. The realized capital loss offsets capital gains from other positions, reducing the current-year tax owed. Net capital losses exceeding gains can offset up to $3,000 of ordinary income per year; any remainder carries forward indefinitely to future years. The key is maintaining market exposure after harvesting — the goal is not to exit the market but to convert a paper loss into a tax asset while remaining invested.
The tax benefit: a $10,000 capital loss in a taxable account offsets $10,000 of capital gains. At the 23.8% long-term capital gains rate (20% + 3.8% NIIT for high-income investors), this saves $2,380 immediately. The offsetting cost: the replacement security has a lower cost basis, meaning future gains will be larger when it is eventually sold. Tax-loss harvesting defers taxes rather than eliminating them permanently — but the deferral value is real and compounds over time. Harvesting is most valuable when: (1) you have substantial realized gains to offset, (2) your tax rate is high, and (3) you have a long time horizon before liquidating the replacement position.
For the full framework, see Tax-Efficient Investing.
Tax-loss harvesting requires execution discipline and awareness of the wash-sale rule. Follow these steps to harvest correctly.
Tax-loss harvesting only applies to taxable brokerage accounts — IRAs and 401(k)s are tax-deferred, so there are no capital gains events within the account and no losses to harvest. In tax-deferred accounts, rebalancing, selling, and reinvesting are all tax-free. The optimal asset location strategy: hold tax-inefficient assets (high-turnover strategies, bonds, REITs) in tax-deferred accounts; hold tax-efficient assets (buy-and-hold equity, low-dividend growth stocks) in taxable accounts where harvesting opportunities arise.
| Scenario | Action | Tax Outcome | Watch Out For |
|---|---|---|---|
| Stock down 20%, thesis intact | Sell, immediately buy a similar ETF | Harvest $X loss; maintain market exposure | Wash-sale rule — don't buy the same or 'substantially identical' security within 30 days |
| Large capital gain elsewhere | Harvest losses to offset gains | Reduce or eliminate capital gains tax due | Match long-term losses to long-term gains for optimal tax rate match |
| High-income year | Harvest losses to offset up to $3,000 ordinary income | Reduce ordinary income tax, carry forward remaining | Losses exceeding $3,000 carry forward indefinitely — use them |
| Year-end rebalancing | Combine rebalancing with harvesting where losses exist | Tax-free rebalancing if losses offset rebalancing gains | Track cost basis carefully after multiple purchase lots |
Harvesting $15,000 of losses to offset gains:
You saved $3,570 in immediate taxes while maintaining semiconductor exposure through AMD. The NVDA position can be re-purchased after 31 days if desired. The tax savings of $3,570 remain invested and compound — at 8% for 20 years, that $3,570 becomes approximately $16,600.
For the full framework, examples, and FAQs, read Tax-Efficient Investing.
Use AIQ stock pages to compare replacement securities when harvesting losses — ensure the replacement provides similar factor exposure (sector, momentum, quality profile) to maintain your portfolio's intended risk profile.
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Tax-loss harvesting's biggest compounding benefit is often invisible: every dollar of tax deferred today remains invested and compounds at market rates until realization. A $10,000 tax loss harvested today that saves $2,380 in immediate taxes (at 23.8% combined rate) keeps that $2,380 invested for potentially decades — at 8% annual return, this deferred $2,380 compounds to approximately $10,500 over 20 years. The compounding value of tax deferral often exceeds the compounding value of most investment alpha decisions.
FAQs
The wash-sale rule (IRS Code Section 1091) disallows a capital loss deduction if you buy a 'substantially identical' security within 30 days before or after selling the original at a loss. The rule prevents investors from harvesting losses while maintaining identical economic exposure. Substantially identical is strictly defined for stocks — selling one stock and buying a different company in the same sector does not trigger the rule. Selling one S&P 500 ETF and buying another S&P 500 ETF tracking the identical index is in a gray area. Selling an ETF and buying one that tracks a closely related but different index (S&P 500 vs. Total Market) is generally accepted.
Tax-loss harvesting is worth it when: (1) you have capital gains to offset — without gains, the loss only saves $3,000 of ordinary income tax per year; (2) your combined capital gains tax rate is high (20%+ federal plus state); (3) you have a long time horizon before needing to liquidate the replacement position (the deferred gain grows, making future tax larger, but the deferral compounds the savings). For investors in the 0% or 15% capital gains bracket, harvesting is less beneficial. For investors in the 23.8% combined rate bracket with substantial gains, it is one of the highest-value tax planning moves available.
No — tax-loss harvesting does not apply to IRAs, 401(k)s, or any tax-deferred or tax-exempt accounts. Within these accounts, you can sell and reinvest without tax consequences, but losses realized within the account provide no deduction — they simply reduce the account balance. Tax-loss harvesting is exclusively a strategy for taxable brokerage accounts where each sale of a position creates a taxable event. The optimal approach: keep high-turnover strategies and assets that frequently generate gains in tax-advantaged accounts; keep long-term buy-and-hold equity in taxable accounts where harvesting opportunities naturally arise.
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