Tax-loss harvesting sounds like something only hedge funds do in late December. In reality, it is one of the most accessible tax planning moves available to everyday investors and founders with taxable brokerage accounts.
Quick definition for skimmers: tax-loss harvesting means selling an investment at a loss on purpose so you can use that loss to reduce taxes on gains (and sometimes a small amount of ordinary income), while keeping your long-term portfolio plan intact.
The idea is simple: you intentionally sell investments that are down so you can use those losses to offset capital gains and, in some cases, even reduce ordinary income. The key is doing it strategically, so you are not just “locking in losses” but improving your after-tax outcome while staying invested in a sensible way.
Quick note: This article is educational, not personal tax advice. If you have a complex situation, like concentrated stock, equity compensation, or a business sale, it is worth looping in a CPA or CFP.
Tax-loss harvesting, in plain English
When you sell an investment for less than you paid for it, you create a capital loss. The IRS generally lets you use capital losses to:
- Offset capital gains (short-term and long-term).
- Offset up to $3,000 of ordinary income per year if your losses exceed your gains ($1,500 if married filing separately).
- Carry forward extra losses to future years if you still have more than you can use this year.
Harvesting is most useful in a taxable brokerage account. It does not work the same way inside tax-advantaged accounts like IRAs and 401(k)s because you cannot deduct capital losses there, and gains are not currently taxed each year.
A quick mini example
Numbers make this click:
- You realize a $10,000 capital gain earlier this year.
- You sell another holding that is down and realize a $10,000 capital loss.
In many cases, those amounts net to roughly $0 net capital gain for federal tax purposes (details depend on short-term vs long-term buckets).
If instead you had $20,000 of losses and no gains, you could generally use $3,000 against ordinary income this year ($1,500 if married filing separately), then carry the remaining $17,000 forward.
Strategy 1: Map your gains first
Tax-loss harvesting works best when you know what you are trying to offset. Before you sell anything, pull together:
- Realized gains and losses year-to-date from your brokerage.
- Expected distributions (some mutual funds pay year-end capital gains distributions you did not “sell” yourself).
- Planned sales you still might make this year, like trimming a position to fund a home down payment.
This helps you right-size your harvesting. You do not need to harvest every loss on the screen. You need enough losses to offset the gains you expect, plus any intentional additional losses (like creating a carryforward) if that fits your multi-year plan.
Small nuance that matters: ETFs generally distribute fewer capital gains than many mutual funds, so “surprise” taxable distributions tend to be more common with mutual funds.
Strategy 2: Harvest what you would trim anyway
This is my favorite starting point because it reduces regret. Look for holdings that are:
- Down meaningfully
- Out of alignment with your target allocation
- No longer a great fit (too speculative, too concentrated, or no longer matches your thesis)
If you were already thinking, “I should probably reduce this,” harvesting turns a painful decision into a productive one. You are not just selling something that is down. You are generating a deductible capital loss you can use now or later.
Strategy 3: Be smart about short-term gains
Not all gains are taxed equally. Short-term capital gains (assets held one year or less) are typically taxed at ordinary income rates, which can be higher than long-term rates.
The netting rules matter here. The IRS nets results in a set order:
- Short-term losses net against short-term gains
- Long-term losses net against long-term gains
- Then any remaining net loss in one bucket can offset net gain in the other
You cannot freely choose the ordering, but you can influence your outcome by deciding which positions and lots you sell. Practically, many investors try to realize losses in a way that helps offset short-term gains, because those gains can be more expensive from a tax perspective.
Founder reality check: If you took profits on a big short-term move this year, harvesting losses can soften the tax hit without undoing the discipline of taking gains.
Strategy 4: Use loss swaps to stay invested
The fear with tax-loss harvesting is missing the rebound. You sell, the market pops, and you feel like you paid for a tax benefit with future returns.
A common solution is a loss swap:
- Sell the investment at a loss
- Buy a similar but not substantially identical investment to maintain market exposure
Examples (general, not a recommendation):
- Sell a U.S. large-cap index fund and buy a different U.S. broad-market fund that tracks a different index
- Sell one broad international fund and buy a different broad international fund with a different underlying index
- Sell a single sector ETF and buy a broader industry ETF that is not identical
Important nuance: Selling an S&P 500 fund and buying a different provider’s S&P 500 fund may be considered “substantially identical” (the IRS does not provide a simple master list). Many investors avoid that direct swap to reduce wash-sale risk.
The goal is to keep your portfolio behaving like your plan, while still making the loss “real” for tax purposes.
This leads directly to the most important trap to avoid: the wash-sale rule.
Strategy 5: Avoid wash sales (the 61-day window)
The wash-sale rule generally disallows a loss if you acquire the same or a substantially identical security within the 30-day period before or after the sale that created the loss. That is a 61-day span that includes the sale date (30 days before, the day of the sale, and 30 days after).
Practical ways investors accidentally trigger wash sales:
- Automatic dividend reinvestment buying shares after you sold for a loss
- Buying the same ETF back a week later because you got nervous
- Buying “the same thing” in a different account you control (including IRAs, HSAs, and sometimes a spouse’s account)
Two helpful habits:
- Turn off dividend reinvestment on positions you might harvest, at least temporarily.
- Document your replacement pick before you trade, so you are not tempted to buy back the same security.
If you do trigger a wash sale in a taxable account, the loss is usually not gone forever, but it is deferred by adding it to the cost basis of the replacement shares. The whole point of harvesting is timing the tax benefit, so a deferral may defeat your goal for this year.
Important edge case: If a wash sale is triggered because the replacement shares were bought in an IRA, the loss can be permanently disallowed rather than deferred. This is one reason to treat “across accounts” wash-sale risk as a first-class planning issue.
Strategy 6: Build carryforwards on purpose
If your harvested losses exceed your gains, you can typically deduct up to $3,000 against ordinary income ($1,500 if married filing separately) and carry the rest forward.
Why would you want a carryforward?
- You expect a future liquidity event, like selling a business, real estate, or a concentrated stock position
- You anticipate rebalancing a big taxable portfolio in coming years
- You may be in a higher bracket later and want the flexibility
This is where tax-loss harvesting becomes more than a December tactic. It becomes a multi-year planning tool. A carryforward is like a “coupon” you can apply to future gains, and for entrepreneurs, flexibility is often the most valuable financial asset.
Strategy 7: Use specific ID for lot selection
If you own the same investment purchased at different times and prices, you have multiple tax lots. When you sell, you can often choose which lot you are selling.
Many brokerages default to FIFO (first in, first out). But if your brokerage allows it, using specific identification lets you:
- Sell the lots with the biggest losses to harvest more
- Or, in other situations, sell lots with long-term gains instead of short-term gains
- Keep other lots intact for future planning
Two reminders:
- Make sure your account is set up for the lot method you want before trading.
- Save confirmations and notes on which lots you selected.
This is a small operational detail that can have a surprisingly large tax impact, especially if you have been buying into a fund monthly for years.
Year-end checklist
- Pull realized gains and losses year-to-date.
- Scan for embedded losses you are comfortable selling.
- Choose replacement holdings (if you want to stay invested) that are not substantially identical.
- Disable dividend reinvestment on harvested positions to reduce wash-sale risk.
- Check every account you control for wash-sale risk (taxable, IRA, spouse, and any automatic buys).
- Confirm your cost basis method and pick tax lots deliberately.
- Keep records of trades and the rationale, especially if you are swapping funds.
- Sanity-check costs (spreads, fees, and tracking error) so the tax benefit is not eaten up by trading friction.
One more nuance: state tax treatment can differ from federal rules, so if you are in a high-tax state, the after-tax math may change.
Common questions
Does tax-loss harvesting work if I do not have any gains this year?
It can. You may be able to deduct up to $3,000 of net capital losses against ordinary income ($1,500 if married filing separately), and carry forward the rest. The value depends on your tax bracket and whether you expect future gains.
Can I do tax-loss harvesting in my IRA or 401(k)?
Not in the usual sense. You cannot deduct capital losses inside these accounts, and gains are not currently taxed each year, so tax-loss harvesting is not applicable the way it is in a taxable brokerage account.
Also watch the wash-sale trap: buying substantially identical securities in an IRA can trigger a wash sale tied to your taxable-account sale, and that loss can be permanently disallowed.
Is it always smart to harvest losses?
Not automatically. If selling would push you out of your intended asset allocation, trigger a wash sale, or create trading costs that outweigh the tax benefit, it may not be worth it. The best harvesting is boring and disciplined, not frantic.
What is “substantially identical” for wash sales?
The IRS language is intentionally broad, and there is not a simple master list. As a rule of thumb, avoid selling an ETF and buying another ETF that tracks the exact same index, even if it is from a different provider. When in doubt, consult a tax professional.
The real goal
Tax-loss harvesting is not about being “right” about a stock. It is about being intentional with the tax code so you keep more of what your portfolio earns.
If you want to make this easier on Future You, set up a simple habit: review gains, losses, and allocation once per quarter. That spreads the decision-making out and makes year-end harvesting feel like routine maintenance instead of financial triage.
