Tax-loss harvesting in taxable brokerage accounts is one of the highest-ROI 15-minute tasks in personal finance. The 2026 deadline is Thursday, December 31 — trades must settle in-year, so don't leave it to the last trading day.
The rules, in plain English
1. Capital losses first offset capital gains of the same type (short-term losses offset short-term gains; long-term offsets long-term). 2. Excess losses then cross over (short-term can offset long-term gains). 3. Net losses beyond that offset ordinary income, capped at $3,000/year. 4. Unused losses carry forward indefinitely.
A concrete example
You have a brokerage account with $8,000 in realized short-term gains from a 2026 stock sale. You also have $5,000 of unrealized losses in another position.
Sell the losers: $5,000 loss offsets $5,000 of the gain. Taxable gain drops from $8,000 to $3,000. At a 32% federal bracket + 5% state, that's $1,850 saved on the tax bill.
If you had $0 gains but $5,000 in losses, you could offset $3,000 of salary income (worth ~$1,110 at 37%) and carry $2,000 forward to 2027.
The wash-sale trap
You cannot buy the same or "substantially identical" security within 30 days before or after the loss sale — or the loss is disallowed and added to the replacement's cost basis. Safe workaround: sell VOO (S&P 500), buy IVV (also S&P 500) for 31 days, swap back.
For individual stocks, there's no wash-sale-safe identical replacement. You either sit out 30 days or switch to a sector ETF.
Crypto
Wash-sale rules don't apply to crypto in 2026 — Congress still hasn't closed the loophole. You can sell BTC at a loss at 11pm and rebuy at 11:01pm. (This may change; watch for year-end tax bills.)
What to do this week
1. Run a gain/loss report in your brokerage (usually one click). 2. Identify positions with losses you'd be okay selling. 3. Calculate your net gain position for the year. 4. Execute by December 30 to allow T+1 settlement.
Our Capital Gains Calculator runs the full offset logic with short/long buckets.