Tax-loss harvesting is the practice of selling investments that have decreased in value to realize a capital loss, which can then be used to offset taxable capital gains — reducing your investment tax bill. It is one of the most effective tax optimization strategies available to individual investors, and it requires no change to your long-term investment plan.
How Tax-Loss Harvesting Works
When you sell an investment at a loss, that loss can offset capital gains you have realized elsewhere. If your losses exceed your gains, you can use up to $3,000 of the remaining loss to offset ordinary income each year. Any losses beyond that carry forward indefinitely to future tax years.
Simple example:
- You sell Stock A for a $5,000 gain
- You sell Fund B (which has declined) for a $3,000 loss
- Net taxable gain: $2,000 instead of $5,000
- At a 15% long-term capital gains rate, you save $450 in taxes
Tax-Loss Harvesting Rules
Short-Term vs. Long-Term Capital Gains
Capital gains are taxed differently based on how long you held the investment:
- Short-term gains (held less than 1 year): taxed as ordinary income (10% to 37%)
- Long-term gains (held 1 year or more): taxed at preferential rates of 0%, 15%, or 20% depending on income
Short-term losses must first offset short-term gains; long-term losses must first offset long-term gains. Any excess losses from one category can then offset the other.
The Wash-Sale Rule
The IRS wash-sale rule prevents “harvesting” a loss and immediately buying back the same security. If you sell an investment at a loss and then buy a “substantially identical” security within 30 days before or after the sale, the loss is disallowed.
“Substantially identical” typically means the exact same security. To maintain market exposure while avoiding a wash sale, you can:
- Buy a similar but not identical investment — sell a Vanguard S&P 500 ETF and buy a Fidelity S&P 500 ETF
- Wait 31 days before repurchasing the original investment
- Use a total market ETF instead of a specific index ETF
Cost Basis Methods
Your capital gain or loss depends on which shares you are treated as selling. Common cost basis methods:
- FIFO (First In, First Out): Default for most accounts; oldest shares sold first
- Specific identification: Choose exactly which shares to sell — allows you to sell highest-cost shares to minimize gains or lowest-cost shares to maximize harvested losses
- Average cost: Available for mutual funds; uses average purchase price
For tax-loss harvesting, specific identification gives you the most control.
When to Harvest Tax Losses
Tax-loss harvesting can happen any time during the year when you have unrealized losses in taxable accounts, but the most common approach is:
- Year-end harvesting: Review your portfolio in November/December, harvest losses before December 31
- Opportunistic harvesting: When markets drop significantly (e.g., after a 10%+ drawdown), harvest losses before markets recover
- Ongoing automated harvesting: Many robo-advisors harvest continuously throughout the year, capturing every opportunity
How Much Does Tax-Loss Harvesting Actually Save?
The benefit depends on your tax rate, how much you have to harvest, and when you eventually sell your replacement investment. Tax-loss harvesting does not eliminate taxes — it defers them. When you sell the replacement investment later, your lower cost basis means a larger gain to pay taxes on.
However, deferral has real value: a tax dollar deferred for 20 years is worth significantly less in present-value terms than a dollar paid today. At a 7% annual return, deferring $1,000 in taxes today means that money compounds to $3,870 over 20 years before the deferred tax comes due.
Vanguard research estimates that consistent tax-loss harvesting can add roughly 0.5% to 1.8% per year in after-tax returns depending on portfolio volatility and tax rate — meaningful value over decades of investing.
Tax-Loss Harvesting in Retirement Accounts
Tax-loss harvesting does NOT apply to tax-deferred accounts like traditional IRAs, Roth IRAs, or 401(k)s. Within these accounts, gains are not currently taxable, so there is no tax benefit to realizing losses. Only losses in taxable (non-retirement) brokerage accounts can be harvested.
Robo-Advisor vs. DIY Tax-Loss Harvesting
Automated robo-advisors like Betterment and Wealthfront monitor your portfolio daily (or continuously) and harvest losses automatically throughout the year, capturing opportunities a human investor might miss. For accounts with substantial balances, the annual fee (0.25%) is often worth it purely for the tax savings from automated harvesting.
DIY harvesting requires you to manually review your portfolio, identify losers, select a replacement, and track wash-sale rules. It is feasible but more time-intensive and error-prone.
Advanced Tax-Loss Harvesting: Direct Indexing
Direct indexing takes tax-loss harvesting to the next level. Instead of holding an S&P 500 ETF, you hold all 500 individual stocks directly. This allows harvesting losses on individual stocks that have declined even while the overall index is up — dramatically increasing the amount of losses available to harvest each year.
Direct indexing is typically available through robo-advisors like Wealthfront and Parametric for accounts of $100,000 or more. It makes the most sense for investors in the highest tax brackets with large taxable portfolios.
Tax-Loss Harvesting FAQ
Can I harvest losses in a down market and still maintain my target allocation?
Yes. Sell the losing position and immediately buy a similar-but-not-identical replacement to maintain market exposure. This is the core of tax-loss harvesting — you stay invested while capturing the tax benefit.
Can I carry forward capital losses indefinitely?
Yes. Capital losses that cannot be used in the current year (because you have no gains to offset and you have already used the $3,000 income offset) carry forward indefinitely to future tax years.
Does tax-loss harvesting work for cryptocurrency?
Yes. Cryptocurrency is treated as property for tax purposes, so losses can be harvested like any other asset. Importantly, the wash-sale rule does not currently apply to cryptocurrency — you can sell and immediately repurchase the same coin. However, proposed legislation may change this; consult a tax advisor for current rules.