Tax-loss harvesting is the only legal way to turn a paper loss into real money. Sell something at a loss, take the deduction, buy something similar to keep your portfolio allocation. The IRS has one big rule (the wash-sale rule) and a lot of asterisks.
This guide covers the mechanics, the wash-sale trap, and the math that determines whether harvesting is actually worth doing.
How tax-loss harvesting works in 2026
- Capital losses offset capital gains dollar for dollar — short-term losses against short-term gains first, then long-term against long-term.
- Excess losses offset up to $3,000 of ordinary income per year ($1,500 if married filing separately).
- Remaining losses carry forward indefinitely — useful for future high-income years.
A $20,000 long-term gain plus a $25,000 harvested loss leaves a $5,000 net loss. $3,000 reduces this year's W-2 income; $2,000 carries to next year.
The wash-sale rule
The IRS won't let you sell a stock for a loss and buy it right back. Specifically: if you buy the same or "substantially identical" security within 30 days before or after the sale, the loss is disallowed and added to the basis of the new purchase.
- Spouses and IRAs count too — a wash sale in your spouse's account or your own IRA disallows the loss.
- "Substantially identical" is fuzzy — switching from Vanguard's S&P 500 fund (VOO) to iShares Core S&P 500 (IVV) likely triggers a wash sale. Switching to a total market fund (VTI) likely doesn't.
- Crypto is currently exempt — Build Back Better tried to extend wash-sale rules to digital assets and failed. Several 2026 bills propose closing this; nothing has passed as of this writing.
How to do it without breaking the rule
- Step 1: Identify a holding with a loss.
- Step 2: Find a "similar but not identical" replacement — e.g., S&P 500 → Russell 1000.
- Step 3: Sell the loser, buy the replacement on the same day.
- Step 4: Wait 31 days before switching back if you want to.
- Step 5: Document everything. Brokers report wash sales but their flagging isn't perfect.
1. Year-end harvesting — best for most investors
December is the standard time to harvest. You know your year's gains, you know your bracket, and you have time to clean up before December 31.
The trade-off: everyone else is harvesting too, which can move prices. Don't wait until December 30.
2. Continuous harvesting via robo-advisors — best for high earners
Betterment, Wealthfront, and Schwab Intelligent Portfolios scan daily and harvest opportunistically. Adds an estimated 0.20–0.40% to after-tax returns for high-income investors.
The catch: it works best in taxable accounts and only when you're in higher brackets. For a 12% bracket investor it's mostly busywork.
3. Crypto harvesting — best while the loophole lasts
No wash-sale rule means you can sell BTC at a loss and buy back the same minute. Until Congress changes this, it's the most aggressive harvesting available.
The catch: legislation has been proposed in every Congress since 2021. It will likely happen eventually.
Comparison: harvesting approaches in April 2026
| Approach |
Best for |
Annual benefit |
Effort |
| Manual year-end |
DIY investors |
$300–$2,000 |
2 hours |
| Robo-advisor auto |
High earners |
0.20–0.40% return |
None |
| Crypto opportunistic |
Active crypto holders |
Variable, large |
Ongoing |
| Direct indexing |
Investors with $100K+ taxable |
0.50–1.00% return |
None |
| None |
12% bracket or below |
Negligible |
None |
Common mistakes to avoid
Buying the same fund in your IRA. A wash sale in your IRA disallows the loss in your taxable account permanently — the basis adjustment goes to a tax-advantaged account where it does nothing.
Triggering a wash sale via dividend reinvestment. DRIPs buy shares automatically. Turn them off in any account where you might harvest losses.
Harvesting in a 0% capital gains bracket. If your long-term gains rate is 0% (income under ~$94,050 married filing jointly), harvesting losses is wasteful. Harvest gains instead.
FAQ
Can I claim a wash-sale loss later?
Yes, eventually. The disallowed loss adds to the basis of the replacement shares, so when you finally sell those, the loss surfaces.
Does tax-loss harvesting work in retirement accounts?
No. Gains and losses inside IRAs and 401(k)s aren't taxable events.
What's the deadline?
December 31 of the tax year. Trades must settle (T+1 in 2026) before year-end.
Where to go next
For related guides see Crypto tax reporting in 2026, How to pick a brokerage account for beginners 2026, and What 1% fees cost over 30 years 2026.