How to actually harvest a tax loss

Tax loss harvesting means selling an investment at a loss, then using that loss to reduce the taxes you owe on investment gains or other income. The mechanics are straightforward: you identify a holding that has dropped below what you paid for it, sell it, and report the loss on your tax return. The IRS lets you use up to $3,000 of net losses against ordinary income each year, and carry unused losses forward indefinitely.

The real work is not the selling—it is the record-keeping and the decision about what to buy next. Most people who harvest losses do it in December, when year-end statements make it straightforward to spot which positions are underwater. But you can harvest any time the market moves a holding into loss territory.

Key Takeaways

  • You must sell the losing position and report the sale on Schedule D (Capital Losses) to claim the loss on your tax return.
  • The wash-sale rule blocks you from buying the same or substantially identical security within 30 days before or after the sale, or the loss is disallowed.
  • You can use $3,000 of net losses per year against wages, interest, or other ordinary income; losses beyond that carry forward to future years.
  • Harvested losses offset capital gains dollar-for-dollar first, then reduce ordinary income, so the tax benefit depends on your income level and other gains.
  • Tracking your cost basis and sale price is essential—your brokerage provides this on year-end statements, but you must report it correctly on your return.

Identify which positions are in loss territory

Pull up your brokerage account and look at each holding's current value versus your cost basis—the amount you originally paid. Your brokerage statement shows both. A position is harvestable if the current market value is lower than your cost basis.

You do not have to harvest every loss. You might hold a position because you believe it will recover, or because selling it would trigger other consequences (like losing a dividend reinvestment plan or disrupting a long-term strategy). Harvest only the losses that make sense for your situation.

If you have multiple losing positions, prioritize the largest losses first, since they reduce the most tax. If you have both gains and losses in the same year, losses offset gains before they offset ordinary income, so a large loss might eliminate a gain entirely.

Sell the position and document the transaction

Place a sell order for the full position or the portion you want to harvest. Your brokerage will execute it at the market price on that day. Once the trade settles (usually two business days later), the cash appears in your account.

Write down or screenshot the sale details: the security name and ticker, the number of shares sold, the sale price per share, the total proceeds, and the date of the sale. Your brokerage will send you a confirmation email and include the transaction on your monthly statement. Keep these records—you will need them to fill out your tax forms.

The loss amount is the difference between your cost basis and the sale price. If you bought 100 shares of a fund at $50 per share ($5,000 total) and sold them at $40 per share ($4,000 total), your loss is $1,000.

Understand the wash-sale rule before you reinvest

The wash-sale rule is the main trap in tax loss harvesting. It says the IRS will disallow your loss if you buy the same security, or a substantially identical one, within 30 days before the sale or 30 days after the sale. The window is 61 days total: 30 days before, the day of the sale, and 30 days after.

If you violate the wash-sale rule, the loss does not disappear—it gets added to the cost basis of the replacement security instead. So you lose the when ready tax benefit, but you recover it when you eventually sell the replacement at a gain or loss.

To avoid the rule, wait 31 days after the sale before buying back the same security. Or buy something different in the meantime. Many people harvest a stock fund loss and when ready buy a similar but not identical fund—for example, selling a total US stock fund and buying a large-cap value fund. The IRS considers these substantially different, so the wash-sale rule does not explore. Check your brokerage's fund comparison tool or ask whether two funds are substantially identical before you buy.

Report the loss on Schedule D when you file

When you file your tax return, you report all investment sales on Schedule D (Capital Gains and Losses). This form has two sections: short-term gains and losses (holdings you owned less than one year) and long-term gains and losses (holdings you owned more than one year).

For each sale, you list the security name, the date acquired, the date sold, your cost basis, the sale price, and the gain or loss. Your brokerage usually provides a year-end statement that shows all this information. Many tax software programs (TurboTax, H&R Block, TaxAct) can import this data directly from your brokerage, which reduces the chance of entry errors.

At the bottom of Schedule D, you calculate your net gain or loss. If your losses exceed your gains, you can use up to $3,000 of the net loss to reduce your ordinary income (wages, interest, self-employment income, etc.) in that year. Any loss above $3,000 carries forward to the next year, where you can use another $3,000 against ordinary income, and so on until the loss is fully used.

Know how much tax benefit you actually get

The tax savings from a harvested loss depend on your tax bracket. A $1,000 loss saves you $100 in federal tax if you are in the 10% bracket, but $370 if you are in the 37% bracket. Your tax bracket is determined by your total income for the year.

Losses offset capital gains first, dollar-for-dollar. If you harvested a $2,000 loss and also have $1,500 in capital gains, the loss eliminates the gain and leaves $500 of loss to use against ordinary income. If you have no capital gains, the full $2,000 loss can reduce ordinary income (up to the $3,000 annual limit).

State income tax also matters. Some states do not tax capital gains (like Washington and Florida), so harvesting a loss there saves you only federal tax. Other states tax capital gains as ordinary income, so the state tax benefit can be substantial. Check your state's rules or ask a tax professional about your specific situation.

Track your cost basis and keep records

Your brokerage is required to track and report your cost basis to the IRS. But you should verify it yourself, especially if you have made reinvestments, received dividends, or held the position for many years.

Cost basis is not always straightforward. If you bought shares at different times, you must choose which shares you are selling: first-in-first-out (FIFO), last-in-first-out (LIFO), average cost, or specific identification. Most brokerages default to FIFO, but you can usually change this before you sell. Choosing a method that maximizes your loss (like specific identification of the highest-cost shares) is legal and often smart.

Keep your brokerage statements, trade confirmations, and any dividend reinvestment records for at least three years after you file the return reporting the sale. The IRS can audit back further if it suspects underreporting, so keeping records longer is safer.

Frequently Asked Questions

Can I harvest a loss in a retirement account like a 401(k) or IRA?

No. Retirement accounts are tax-deferred, so gains and losses inside them do not affect your current-year taxes. The IRS does not allow you to harvest losses in these accounts. You can only harvest losses in taxable brokerage accounts.

What counts as a substantially identical security for the wash-sale rule?

The IRS does not publish a detailed list, but generally a different fund or security is not substantially identical if it has a different investment strategy, different holdings, or a different expense ratio. Selling a total US stock fund and buying a large-cap value fund is usually safe. Selling a fund and buying an ETF that tracks the same index is risky—they may be considered substantially identical. When in doubt, ask your brokerage or a tax professional.

Do I have to harvest losses in December, or can I do it anytime?

You can harvest any time a position is in loss territory. December is popular because year-end statements make it straightforward to spot losses, and you can use the loss in the current tax year. But if a position drops in loss territory in March, you can harvest it then and use the loss on that year's return.

What happens to my harvested loss if I never have capital gains?

You can use up to $3,000 of net losses against ordinary income (wages, interest, self-employment income) each year. Any unused loss carries forward to the next year indefinitely. So if you harvest a $5,000 loss and have no capital gains, you use $3,000 this year and $2,000 next year (assuming you have no other losses next year).

Do I need to report harvested losses if my brokerage already reported them to the IRS?

Yes. Your brokerage reports the sale to the IRS on Form 8949 (Sales of Capital Assets). You must report it on your own tax return on Schedule D. If your reported loss does not match what the brokerage reported, the IRS will notice and may send you a notice. Make sure your cost basis and sale price match what your brokerage reported.