Tax Loss Harvesting Calculator

Tax-loss harvesting means deliberately selling an investment that has fallen, so the loss becomes real and can be set against your capital gains. The cash goes straight back into something similar but not “substantially identical”, so your market exposure never breaks.

The core tax savings formula:

Tax Savings = Realized Loss × Applicable Tax Rate

Net Benefit = Tax Savings − Transaction Costs − Reinvestment Costs

Tax rate context (US, 2026):

Worked example: An investor in the 24% income tax bracket has:

• $8,000 in short-term capital gains from selling stock A
• Stock B has declined, with an unrealized loss of $5,000

Harvest the loss from Stock B:

• Loss offsets the gain: $8,000 − $5,000 = $3,000 net gain
• Tax on $3,000 at 24%: $720 owed (instead of $1,920 on the full $8,000)
• Tax savings: $1,200

Reinvest in a different fund tracking the same broad market. You keep full exposure and you bank the tax benefit.

The Wash-Sale Rule (critical): The IRS prohibits claiming a loss if you buy the “substantially identical” security within 30 days before or after the sale. The wash-sale window is 61 days total (30 days before sale, day of sale, 30 days after).

Loss carryforward: Only $3,000 of net capital loss can offset ordinary income in any one year. Everything past that carries forward indefinitely, usable in full against future gains or $3,000 a year against income.

Limitations: Tax-loss harvesting is most valuable for investors in high income tax brackets with taxable brokerage accounts. It has no benefit in tax-advantaged accounts (IRA, 401k).

This page asks for one rate on your gains, which keeps it quick, and it takes your trading and reinvestment costs off the answer.
If your gains are a mix of holding periods, or you pay state income tax, or you want the carryforward valued rather than just counted, use the tax-loss harvesting savings calculator. It splits short-term from long-term and adds a state rate. On the same inputs both pages return the same saving.