Tax-loss harvesting is the practice of selling an investment that has fallen below what you paid for it, claiming the loss on your tax return, and reinvesting the proceeds so that your portfolio stays fully invested. Done carefully, it turns an unpleasant market move into a real reduction in what you owe. Done carelessly, it produces a disallowed loss, an unintended change to your allocation, or a tax benefit so small that the trade was not worth making.
The mechanics are not complicated, but the boundaries are strict, and two of them surprise almost everyone: a federal deduction cap that has not changed in nearly fifty years, and a repurchase rule that quietly erases the benefit you thought you had captured.
What Tax-Loss Harvesting Actually Does
Realized capital losses first offset realized capital gains of the same character. Short-term losses offset short-term gains, long-term losses offset long-term gains, and any remainder crosses over. If losses still exceed gains after that netting, a limited amount may be deducted against ordinary income, and whatever is left carries forward indefinitely to future tax years. The Internal Revenue Service describes this netting sequence in Topic No. 409, Capital Gains and Losses.
It is worth being precise about the benefit. Harvesting a loss does not usually eliminate tax. In most cases it defers tax, because selling at a loss and buying a replacement resets your cost basis lower, which means a larger gain later when you eventually sell the replacement. The value comes from the time between now and then, and from the possibility that the later gain is taxed at a lower rate or is never realized at all, for example because the position is donated to charity or passes to heirs with a step-up in basis.
The $3,000 Limit Has Not Moved Since 1978
When net capital losses exceed net capital gains, the deduction against ordinary income is capped at $3,000 per year, or $1,500 for a married taxpayer filing separately. Anything above that carries forward.
That figure has been fixed since 1978, and it is not indexed for inflation. The Congressional Research Service has observed that adjusting the limit for inflation would place it in the neighborhood of $13,000 rather than $3,000, and that gap has only widened since. You can read the analysis in the CRS report An Analysis of the Tax Treatment of Capital Losses.
The practical consequence is that a large harvested loss is rarely a large current-year tax refund. An investor who realizes $60,000 of losses in a year with no capital gains deducts $3,000 and carries forward $57,000. At that pace the carryforward would take nineteen years to absorb. This is precisely why harvesting is most valuable to investors who also generate capital gains, through rebalancing, concentrated position sales, mutual fund distributions, or the sale of a business or property.
The Wash Sale Rule Is Where Most Mistakes Happen
Under Internal Revenue Code section 1091, a loss is disallowed if you acquire substantially identical stock or securities within 30 days before or after the sale. Note that the window runs in both directions, which makes it 61 days in total counting the sale date. The IRS explains the rule and its exceptions in Publication 550, Investment Income and Expenses.
Substantially Identical Is the Hard Part
The statute does not define the phrase with precision, and the IRS has not issued bright-line guidance for mutual funds and exchange-traded funds. The generally accepted reading is that two funds tracking the same index are a serious concern, while two funds tracking meaningfully different indexes are usually not substantially identical. Selling one large-cap fund and buying a different fund that holds nearly the same securities in nearly the same weights sits in uncomfortable territory, and reasonable professionals treat it cautiously.
Your IRA Counts, and the Loss Is Gone for Good
This is the version of the rule that costs people the most. In Revenue Ruling 2008-5, the IRS held that if you sell a security at a loss in a taxable account and your traditional IRA or Roth IRA buys a substantially identical security inside the window, the loss is disallowed and your basis in the IRA is not increased to compensate. In an ordinary wash sale the disallowed loss is added to the basis of the replacement shares, so the benefit is postponed rather than lost. In the IRA version there is no basis adjustment available, so the loss disappears permanently. Spousal accounts and accounts you control are treated on the same principle.
Test Your Wash Sale Knowledge
Each scenario below describes a common situation. Open any of them, in any order, to see whether the loss survives and why. All five reflect federal rules in effect for the 2026 tax year.
1. You sell an S&P 500 index fund at a loss on March 3 and buy the same fund back on March 20 in the same taxable account.
2. You sell a stock at a loss in your brokerage account and, nine days later, your Roth IRA buys the same stock.
3. You sell a stock at a loss on December 28 and repurchase it on January 10 of the following year.
4. You buy additional shares of a stock on May 1, then sell your older, higher-basis lot at a loss on May 20.
5. You sell a total US stock market index fund at a loss and immediately buy an international developed markets fund.
Why Tax-Loss Harvesting Works Differently in California
California does not provide a preferential rate for long-term capital gains. As the Franchise Tax Board states on its capital gains and losses page, California taxes capital gains at the same rates as ordinary income, with a top marginal rate of 12.3 percent plus an additional 1 percent mental health services tax on taxable income above $1 million.
That single fact changes the arithmetic in two directions. On one hand, a harvested loss that offsets a California capital gain is offsetting income taxed at full ordinary rates, which makes the state-level benefit larger than it would be in a state with a capital gains preference or no income tax at all. On the other hand, deferral is less attractive when there is no lower rate waiting on the other side, because a long-term holding period earns no state discount. California generally conforms to the federal $3,000 annual limit on deducting net capital losses against ordinary income, so the carryforward problem exists at both levels.
For a Sacramento-area household in a high bracket, the combined federal and state value of a harvested loss can be meaningful. For a household with modest income and no realized gains, the same loss may be worth a few hundred dollars this year and nothing more.
When Harvesting Is Not Worth the Trade
Several situations argue against harvesting even when a paper loss exists. If your taxable income already places you in the zero percent federal long-term capital gains bracket, a loss offsets gains that are not being taxed, which wastes it. If the position sits in a 401(k), 403(b), 457(b), or IRA, there is nothing to harvest, because losses inside tax-deferred accounts have no reportable character. If trading costs, bid-ask spreads, or a fund with a redemption fee consume much of the benefit, the trade is not paying for itself. And if the only acceptable replacement is a fund you do not actually want to own, the allocation cost may exceed the tax savings.
One further note for readers who hold digital assets: the wash sale rule in section 1091 applies to stock and securities, and the IRS treats cryptocurrency as property rather than as a security, so spot cryptocurrency has not been subject to the rule. Legislation to extend it to digital assets has been introduced in Congress more than once and has not been enacted as of this writing. Anyone relying on the current treatment should confirm that it still holds before acting.
Building Tax-Loss Harvesting Into a Routine
The most common failure is not a technical one. It is that harvesting only gets attention in late December, when losses have often already recovered and the calendar is crowded. Opportunities appear during the year, frequently in short drawdowns that reverse within weeks.
A workable routine has a few elements: track cost basis by tax lot rather than by average, so that individual purchases can be identified; turn off automatic dividend reinvestment in taxable accounts, or at least know the reinvestment dates, since those purchases can trigger the rule; identify replacement holdings in advance so that a decision does not have to be improvised; and coordinate harvesting with rebalancing, since the two often want the same trades. We help clients pair tax-loss harvesting with the rest of the plan, so that a tax decision does not quietly become an unintended investment decision.
Talk Through Your Own Situation
If the scenarios above raised a question about a trade you have already made, or if you are carrying forward losses and are not sure how to put them to use, a conversation is usually the fastest way to get clarity. Rooney Wealth Management offers a free 30-minute call with no obligation. We can look at how your accounts are titled, where your realized gains are likely to come from, and whether harvesting has a role in your plan this year.
You may also reach us any time through our contact page.
Rooney Wealth Management LLC is an investment adviser registered with the state of California. This article is for educational purposes only and is not tax, legal, or investment advice. Please consult your tax or financial professional regarding your specific situation.
