Tax loss harvesting calculator
Enter the loss, the gains you have already realised, and the rate you expect to pay when you finally sell. This runs the offset waterfall, schedules the carryforward, discounts it, then subtracts the tax the basis reset creates later.
Worked example — What the harvest is actually worth, in today's money: $950. On a $20,000 short-term loss against $5,000 of realised gains, against a headline of $6,400
Big loss, capped by the $3,000 rule: The page’s own default, showing the carryforward mechanic most competing calculators ignore.
Advanced options 2
Losses offset gains of the same holding period first, then gains of the other holding period, then up to $3,000 of ordinary income a year, with the rest carried forward and released at that cap. The carryforward schedule assumes no realised gains in later years, the conservative reading. All rates, the cap, and the window are values you entered: this page takes them as given and does not determine anyone's bracket.
Tax loss harvesting value by future tax rate
On the default scenario, a $20,000 short-term loss against $5,000 of realised gains, 5 years to the sale, here is the net present value of harvesting today at each future tax rate.
| Rate when you finally sell | Net value of harvesting today | Against the headline |
|---|---|---|
| 0.0% | +$5,964 | $6,400 |
| 5.0% | +$5,181 | $6,400 |
| 10.0% | +$4,397 | $6,400 |
| 15.0% | +$3,614 | $6,400 |
| 20.0% | +$2,830 | $6,400 |
| 25.0% | +$2,046 | $6,400 |
| 30.0% | +$1,263 | $6,400 |
| 35.0% | +$479 | $6,400 |
| 40.0% | -$304 | $6,400 |
The value crosses zero somewhere below 40.0%. Above that, harvesting today costs money.
What happens if I trigger a wash sale?
Buy the replacement back inside the wash-sale window and the loss is disallowed this year: the benefit is $0, and the $20,000 is rolled into the replacement position's basis instead of deducted. It is not destroyed, only postponed. Selling and then sitting out 31 days before buying back, on the same inputs, is worth $950. What sitting out actually costs is being out of the position for those days, a market-exposure cost this page has no inputs to price.
How much is a $20,000 loss actually worth after the $3,000 cap?
Against $5,000 of already-realised short-term gains and a $3,000 annual cap on ordinary income, $2,560 of this year's tax saving is usable now and the rest carries forward for 4 more years at the cap. Present-valued at a 5.0% discount rate, the whole schedule is worth $5,964 before the basis reset, and $950 after it, against a naive headline of $6,400 that ignores both the cap and the basis reset.
| Year | Applied against | Loss used | Tax saved |
|---|---|---|---|
| This year | Offsets short-term gains | $5,000 | $1,600 |
| This year | Offsets ordinary income, up to the annual cap | $3,000 | $960 |
| Year 1 | Carried forward to year 1 | $3,000 | $960 |
| Year 2 | Carried forward to year 2 | $3,000 | $960 |
| Year 3 | Carried forward to year 3 | $3,000 | $960 |
| Year 4 | Carried forward to year 4 | $3,000 | $960 |
The next question after this one
Capital gains holding period calculatorCalculatorThe harvest resets the basis and the clock. This prices what the shorter holding period costs on the way back.Open nextOther questions
All 130 calculatorsHow JMM sources and checks its numbersWhat stays free, and what early access would add
What Pro adds here
Lot-level harvesting across a whole portfolio, substitute-position tracking error, and a multi-year harvest plan are Pro features. The launch list sends one email at launch.