Tax-Loss Harvesting Calculator

How the saving is calculated

The calculator follows Schedule D. Short-term gains and losses (held one year or less) net against each other, long-term ones (held more than a year) net against each other, and only then do the two totals offset. A net short-term gain is taxed at your ordinary rate. A net long-term gain is taxed at 0%, 15% or 20%, with the rate set by where the gain lands once it is stacked on top of your ordinary taxable income. If losses are left after every gain is gone, up to $3,000 ($1,500 married filing separately) comes off ordinary income and the rest carries forward.

The saving is your federal tax computed twice, with and without the harvested losses, so a loss that pulls income out of a higher bracket is valued at that bracket. It includes the 3.8% net investment income tax, which applies to the smaller of your investment income and your modified AGI above $200,000 single or $250,000 married filing jointly. At $300,000 of income, a $20,000 short-term loss saves $7,760 in this model where the same long-term loss saves $3,760, because short-term gain is the expensive kind.

The wash-sale rule

A loss does not count if you buy substantially identical stock or securities within 30 days before or after the sale. Purchases by a spouse, in an IRA, and automatic dividend reinvestment all count. A disallowed loss in a taxable account moves into the basis of the new shares, so the deduction is postponed; a repurchase inside an IRA loses it outright. This calculator assumes your losses are allowed, so check your other accounts before you trade. Under current law the rule covers stock and securities, and cryptocurrency held directly is property rather than a security, so as of October 2026 a crypto sale and repurchase is not a wash sale. Our guide to what tax-loss harvesting is walks through the window with dates.

Deferral, not elimination

Selling at a loss and buying a replacement leaves you with a lower cost basis. In the $150,000 example above, the replacements carry a basis $50,000 lower, and selling them later as a long-term gain in a year with the same income and no other gains would add about $7,500 of federal tax. That tax is postponed, not erased. Harvesting comes out ahead for good when the loss offsets income taxed at a higher rate than the later gain, such as short-term gain or the $3,000 ordinary offset, or when you hold the replacement until death and your heirs receive a stepped-up basis, which erases the deferred gain.

The carryforward is shown at face value. It is worth what it saves in the years you use it: in full against future gains, or $3,000 a year against ordinary income when there are no gains. The card shows what it would save in a year that looks like this one.

When to harvest

A loss counts in the year the trade executes, so for 2026 the sale must have a trade date of December 31 or earlier. That deadline sits alongside others on our 2026 financial deadlines list. Losses also appear during the year when markets drop, and harvesting then, rather than waiting for December, captures losses that might recover by year end. Nino’s software checks your taxable brokerage accounts for positions with $1,000 or more of losses, skipping robo-managed accounts and anything bought in the last 31 days, names them with the December 31 deadline, and estimates the federal tax saved from each lot. It never places the trade.