U.S. · Investments and tax
Tax loss harvesting calculator.
Enter your gains so far and the loss you could take. See the tax it saves and what carries over.
A harvested loss first cancels capital gains, then lowers other income by up to $3,000 ($1,500 if married filing separately). The rest carries to next year. A short-term loss usually saves more than a long-term loss because it offsets gains taxed at ordinary rates.
Your year so far
Your estimate
How tax loss harvesting works
Tax loss harvesting means selling investments that are worth less than you paid so the loss offsets taxable gains, then keeping your portfolio invested in something similar. The US tax code nets your gains and losses in a fixed order: short-term with short-term, long-term with long-term, then the two net results against each other. Whatever loss remains reduces other income by up to $3,000 ($1,500 if you are married filing separately), and the rest carries forward. The calculator above runs that netting twice, before and after the loss you plan to take, and prices each result at the rates you enter. The difference is your estimated saving.
Worked example: short-term or long-term loss
Sam files single, taxed at 24% on ordinary income and 15% on long-term gains. In 2026 Sam has realized $8,000 of short-term gains and $12,000 of long-term gains, and holds a fund that is down $10,000. Without any harvest the estimated tax on gains is 8,000 × 24% + 12,000 × 15% = $1,920 + $1,800 = $3,720.
- If the $10,000 loss is long-term, long-term gains shrink to $2,000. Tax is $1,920 + $300 = $2,220, a saving of $1,500.
- If the $10,000 loss is short-term, it wipes out the $8,000 short-term gain and the remaining $2,000 loss reduces long-term gains to $10,000. Tax is 10,000 × 15% = $1,500, a saving of $2,220.
The same dollar loss saves $720 more when it is short-term, because it first cancels gains taxed at the higher rate. The form above is preloaded with this case, so change the loss between the short-term and long-term boxes to see it.
The rates behind the estimate
Enter your own marginal rate for ordinary income and your long-term rate. For 2026 the IRS sets the 0% long-term rate up to taxable income of $49,450 for single filers and $98,900 for married filing jointly. The 15% rate applies up to $545,500 for single filers and $613,700 for joint filers, and 20% above that. The 3.8% net investment income tax applies to net investment income when modified adjusted gross income is above $200,000 single or $250,000 joint, so tick the box if you are above the line. State tax is not included.
Limits and traps
- Wash sale rule. Buying a substantially identical security 30 days before or after the sale disallows the loss. The window is 61 days, and it includes purchases in an IRA. Use the wash sale rule calculator to check a pair of trades.
- Deferral, not forgiveness. The replacement holding has a lower basis, so the gain comes back when you sell it.
- Carryovers. Net losses above the annual limit carry forward indefinitely. Enter last year's carryover in the boxes above so it is used first.
- Costs. Trading costs, bid-ask spreads and a change in what you hold can eat a small saving. A harvest is worth most when gains and rates are high.
- Not for retirement accounts. Gains and losses inside an IRA or 401(k) are not reported on your return.
The tax on the gains themselves can be worked out in the capital gains tax calculator, and the effect on the surtax in the net investment income tax calculator. Canadian investors should use the superficial loss calculator.
Sources
Retrieved October 26, 2026.
- IRS Topic 409, Capital gains and losses (retrieved 2026-10-26): long-term versus short-term, $3,000 ($1,500 married filing separately) limit and carryover, page reviewed 24 September 2026.
- IRS Publication 550, Investment Income and Expenses (retrieved 2026-10-26): capital loss limit and carryover example (Bob and Shelly), wash sale rule.
- IRS Revenue Procedure 2025-32 (retrieved 2026-10-26): 2026 long-term capital gain rate thresholds.
- IRS Topic 559, Net investment income tax (retrieved 2026-10-26): the 3.8% tax and its income thresholds.
As of October 26, 2026 these are the current rules for the 2026 tax year.
Frequently asked questions
How much does tax loss harvesting save?
It saves the harvested loss multiplied by the tax rate it offsets. A $10,000 loss against short-term gains taxed at 24% saves about $2,400, while the same loss against long-term gains taxed at 15% saves about $1,500. Losses beyond your gains cut ordinary income by up to $3,000 a year, saving that amount times your bracket.
How much capital loss can I deduct in a year?
Losses first offset capital gains. If losses are larger, you can deduct the lesser of $3,000 ($1,500 if married filing separately) or your net loss against other income, per IRS Topic 409. Anything left carries forward to later years with no expiry.
Do short-term or long-term losses save more?
Usually short-term, because short-term gains are taxed as ordinary income and the loss first nets against short-term gains. A long-term loss offsets long-term gains taxed at 0%, 15% or 20% plus the 3.8% net investment income tax if it applies. The calculator above shows both on your numbers.
Does the wash sale rule cancel my harvest?
It can. If you buy substantially identical stock or securities within 30 days before or after the sale, the loss is disallowed and added to the basis of the new shares. Wait 31 days, or buy something that is not substantially identical. Our wash sale calculator shows the 61-day window and the basis change.
Is tax loss harvesting the same as avoiding tax?
No. It mostly defers tax. Selling at a loss and buying a similar holding lowers your cost basis, so you owe more tax on the gain later. The benefit is the time value of the deferral, and a permanent saving only if you later hold until death or sell in a lower-tax year.
Can I harvest losses in an IRA or 401(k)?
No. Gains and losses inside a traditional IRA, Roth IRA or 401(k) are not reported, so there is nothing to offset. Buying the same security in an IRA within the wash sale window can also disallow a loss in a taxable account.
When is the deadline to harvest for this tax year?
The sale must settle in the tax year. Trades made at the very end of December settle a day or two later, so check your broker’s settlement calendar for the last trade date. This page does not know your broker’s dates.
Not tax advice
This is an estimate for planning, not tax advice. It ignores state tax, alternative minimum tax, the wash sale rule and your other income. Confirm with a tax professional before you trade for tax reasons. Everything runs in your browser; nothing you enter is sent anywhere.