Tax Loss Harvest Calculator
Enter your realized gains and the losses sitting in your portfolio. The calculator sizes the harvest: what to sell by December 31, what it saves in tax, and what carries into next year.
Loss harvesting is the rare tax move with a hard deadline: losses sold by the last trading day of the year offset this year gains, then up to 3,000 of ordinary income, then wait. The whole move dies on one rule - wash sale - so the calendar matters as much as the math.
How to use
- Realized gains first: what you already sold for a profit this year.
- Unrealized losses: current losses available to sell - brokerage lots view shows them directly.
- Your marginal tax rate. The savings figure updates as you type - deadline is Dec 31, no extensions.
Frequently asked questions
How much tax does loss harvesting actually save?
Every harvested dollar first wipes out a dollar of gains you would have paid tax on, then up to 3,000 against ordinary income at your marginal rate - at 22 percent, offsetting 4,000 of gains plus the 3,000 income break saves about 1,540. The calculator runs your exact mix.
What is the wash-sale rule in plain terms?
If you buy the same or substantially identical investment within 30 days before or after selling at a loss, the loss is disallowed. Park the proceeds in a similar but not identical fund for 31 days - total-market instead of S-and-P 500 - and calendar both sides of the window.
Do harvested losses expire?
No - unused losses carry forward indefinitely to future years, offsetting gains or 3,000 of income per year. Harvesting more than you can use this year is still worth it if the lots are there.
Does this work in retirement accounts?
No - losses inside an IRA or 401k have no tax effect because those accounts are not taxed on gains either. Harvesting only matters in taxable brokerage accounts; the calculator assumes taxable.