Nobody enjoys watching an investment drop in value. But if it happens in a regular brokerage account, that loss is not purely bad news: it can be sold on purpose and turned into a real tax bill reduction. That trade is called tax-loss harvesting, and a volatile market is exactly when it becomes useful.

The short answer

Tax-loss harvesting means selling an investment at a loss in a taxable account to offset capital gains elsewhere in your portfolio, dollar for dollar with no limit, and up to $3,000 a year against ordinary income if your losses exceed your gains. Anything left over carries forward to future years indefinitely. The one rule that trips people up is the wash sale rule: buy back the same or a substantially identical investment within 30 days before or after the sale, and the loss is disallowed.

How tax loss harvesting actually works

The mechanics run in a specific order:

  1. Losses offset gains first, with no limit. If you sold one investment for a $5,000 gain and another for a $5,000 loss in the same year, they cancel out and you owe capital gains tax on nothing.
  2. Extra losses offset up to $3,000 of ordinary income per year. If your losses exceed your gains, you can deduct up to $3,000 ($1,500 if married filing separately) against wages or other ordinary income.
  3. Anything left over carries forward indefinitely. A loss too large to use in one year does not expire. It rolls into next year, first against future gains, then $3,000 at a time against income, for as long as it takes to use it up.

A quick example: say you have $8,000 in capital gains this year and you sell a losing position for a $12,000 loss. The first $8,000 of the loss wipes out the gains entirely. Of the remaining $4,000, you can deduct $3,000 against your ordinary income this year, and the last $1,000 carries forward to next year.

The wash sale rule: the trap that disallows the loss

The IRS will not let you sell an investment for a tax loss and immediately buy the same thing back. The wash sale rule covers a 61-day window: 30 days before the sale, the sale date itself, and 30 days after. Buy the same or a substantially identical security anywhere in that window and the loss is disallowed.

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The rule follows you everywhere. It applies across every account you own, including a spouse's accounts and your own IRA or 401(k). Sell a fund at a loss in your taxable brokerage account and buy it back inside your IRA within the window, and the loss is permanently disallowed, because an IRA has no cost basis to adjust the way a taxable account does.

The workaround most people use is swapping into something similar but not "substantially identical": selling one S&P 500 index fund and buying a different total-market or S&P 500 fund from another provider, for instance. You stay invested in roughly the same market exposure the entire time, you just do not hold the exact same fund through the window. Note that as of 2026 the wash sale rule does not apply to cryptocurrency, though that is a narrow carve-out worth confirming has not changed before relying on it.

Who this actually helps

Tax-loss harvesting only matters in a taxable brokerage account. Inside a 401(k) or IRA, gains and losses are not taxed as they happen, so there is nothing to harvest. It also matters more or less depending on your tax bracket:

  • Long-term capital gains (held over a year) are taxed at 0%, 15%, or 20% depending on income, with the 0% bracket reaching $49,450 of taxable income for single filers and $98,900 for married couples filing jointly in 2026.
  • Short-term capital gains (held a year or less) are taxed as ordinary income, up to 37%, so offsetting a short-term gain is worth more than offsetting a long-term one.
  • High earners may also owe the 3.8% net investment income tax above $200,000 of income for single filers or $250,000 for married couples filing jointly, another reason the benefit scales with your bracket.

If most of your income and gains already fall in the 0% long-term capital gains bracket, harvesting a loss against a gain you would not have been taxed on anyway does little for you today, though the carryforward can still help in a higher-income future year.

The honest counterargument

Tax-loss harvesting is not free money, and it is worth being precise about what it does and does not do.

  • You are still realizing a loss. The tax savings soften it, but they do not erase it. A $3,000 deduction in the 22% bracket saves about $660, not $3,000.
  • The tax tail should not wag the investment dog. Harvesting only makes sense if you replace the sold position with something similar and stay invested. Selling to harvest a loss and then sitting in cash "until things calm down" is market timing wearing a tax strategy's clothes, and it is the same mistake covered in should you buy the dip and is a market correction coming.
  • It adds complexity. Tracking cost basis, replacement funds, and the wash sale window across multiple accounts is real bookkeeping, and a mistake can quietly disallow the loss you were counting on.

The honest resolution: harvesting is a genuine, legal tax benefit, but it is a secondary optimization on top of a sound portfolio, not a reason to change what you are invested in. See time in the market beats timing the market for the underlying principle it depends on.

What a beginner should actually do

  1. Only look at this in a taxable brokerage account. Skip it entirely for 401(k) and IRA holdings; there is no tax event to offset there.
  2. A down market, like a correction, is when there is the most to harvest. If you are also considering rebalancing during a correction, the same drop can be an opportunity to do both at once: rebalance into the asset that fell, and harvest the loss on the shares you sell to get there.
  3. Swap into something similar, not identical, to stay invested. Do not sell and sit in cash.
  4. Track the wash sale window across every account you and your spouse hold, not just the one where you made the trade.
  5. Many brokerages and robo-advisors will do this automatically for a fee or as a built-in feature; check whether yours already offers it before doing it by hand.
  6. Report it correctly. Capital gains and losses are reported on Form 8949 and Schedule D; a tax professional or filing software will walk through carryforward losses from prior years.
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The actionable takeaway: tax-loss harvesting is worth doing when you already have a loss sitting in a taxable account and you can replace the position with something similar. It is not worth engineering a loss, and it is never worth abandoning your allocation to chase it.

The quick version

  • Tax-loss harvesting sells a losing investment in a taxable account to offset capital gains, dollar for dollar, with no limit
  • Losses beyond your gains offset up to $3,000 a year of ordinary income, and anything left carries forward indefinitely
  • The wash sale rule disallows the loss if you buy the same or a substantially identical investment within 30 days before or after the sale, a 61-day window that spans every account you and your spouse own
  • It only applies to taxable brokerage accounts, not 401(k)s or IRAs
  • The benefit scales with your tax bracket: it does the most for short-term gains and high earners, the least if your gains already fall in the 0% long-term rate
  • Swap into a similar fund to stay invested; selling and sitting in cash is market timing, not tax strategy
  • A market correction is often the best time to look for losses worth harvesting

Handled correctly, tax-loss harvesting turns an already-realized loss into a smaller tax bill without changing what you are actually invested in. That combination, real savings with no change to your plan, is what makes it worth doing.