Tax-loss harvesting is the practice of intentionally selling investments at a loss in a taxable account so that the realized loss can offset other taxable gains — or up to a small amount of ordinary income each year. It is one of the few investing tactics whose value is measurable in dollars rather than performance promises. Done thoughtfully, it can quietly improve after-tax returns year after year.
Where the savings actually come from
Capital losses serve three purposes on a federal tax return:
- Offsetting realized capital gains, dollar for dollar.
- After gains are exhausted, offsetting up to a small annual amount of ordinary income (currently $3,000).
- Anything beyond that carries forward indefinitely to future tax years.
The benefit grows when losses offset short-term capital gains, which would otherwise be taxed at higher ordinary income rates.
The wash-sale rule
The rule is short but trips many investors:
- If you sell a security at a loss and buy the same or a substantially identical security within 30 days before or after the sale, the loss is disallowed.
- The disallowed loss is added to the basis of the replacement security — it is not lost forever, but it is deferred.
- Wash-sale rules apply across all your accounts, including IRAs and a spouse's accounts.
The most common workaround is to swap into a similar but not substantially identical investment (for example, between two broad U.S. equity ETFs that follow different but related indexes). What counts as substantially identical is not always perfectly defined, so coordination with a tax advisor matters.
Where harvesting tends to add the most value
Some accounts and situations benefit more than others:
- High-tax-bracket investors with regular taxable account activity
- Years with large realized gains elsewhere — a business sale, a concentrated stock diversification, large mutual-fund capital-gain distributions
- Periods of meaningful market volatility, which create more harvestable losses
- Investors building a long-term carryforward to apply against future planned gains
Where it does NOT help
Worth understanding the limits:
- Losses inside tax-deferred accounts (IRA, 401(k)) cannot be harvested — gains and losses inside those accounts have no current tax effect.
- Harvesting can lower your cost basis, so a future sale may eventually trigger more gain. The benefit is real but largely a tax deferral plus rate-arbitrage between short-term and long-term rates.
- Frequent harvesting without a thoughtful reinvestment plan can drift a portfolio off its target allocation.
A simple working framework
A reasonable annual workflow:
- Review taxable accounts for unrealized losses at least once a year (some prefer quarterly).
- Confirm replacement positions in advance so the portfolio's market exposure stays intact.
- Track wash-sale risk across all accounts, including a spouse's IRA.
- Coordinate with year-end tax planning so harvested losses meet a known purpose — offsetting gains, building a carryforward, or supporting a Roth conversion strategy.
Frequently Asked Questions
Does tax-loss harvesting hurt long-term returns?
It generally does not, as long as you stay invested with a comparable replacement position. The strategy primarily shifts the timing of taxes, not the underlying market exposure.
How much can I deduct against ordinary income each year?
Currently $3,000 per year for married couples filing jointly or single filers ($1,500 if married filing separately). Anything beyond that carries forward to future tax years until used.
Can I harvest losses in my IRA?
No. Losses inside tax-deferred or tax-free accounts (IRA, Roth IRA, 401(k)) have no current tax effect because gains and losses in those accounts are not currently taxed.
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