Tax Loss Harvesting Calculator: Estimate Your Savings (2026)

Estimate Savings With a Tax Loss Harvesting Calculator

A tax loss harvesting calculator answers one question: how much tax does selling your losing positions actually save? The math runs through four inputs: realized losses, realized gains, your filing status, and your ordinary bracket.

Short-term losses attack short-term gains before anything else.

Long-term losses do the same against long-term gains, and leftovers cross to the other bucket. This guide gives you the formulas, the 2026 rates, and three worked scenarios you can copy with your own numbers. All the numbers here trace back to the IRS rules on capital gains plus the 2026 inflation adjustments.

The Calculator Formula Step by Step

The tax code forces an ordering on your losses before any savings appear. Net your short-term losses against short-term gains first, then do the same for long-term amounts. If one side still shows a loss, it offsets the remaining gain on the other side.

Up to $3,000 of any leftover loss then reduces ordinary income each year, and the rest carries forward. The savings number comes from multiplying each offset bucket by its matching rate. Run the buckets separately or the totals will mislead you.

The full harvesting guide explains why this ordering exists and how brokers apply it in practice.

The short version: short-term dollars save more per loss because ordinary rates run higher than capital gains rates.

2026 Rates That Drive the Savings Number

Savings per dollar of loss depend entirely on which rate the offset removes. A short-term loss deducted at the 24 percent ordinary bracket saves 24 cents per dollar. A long-term loss absorbed by a 15 percent gain saves 15 cents per dollar instead.

High earners add the 3.8 percent NIIT surtax on top of both figures. The table below shows what $10,000 of harvested loss saves at common 2026 income levels.

Notice the strange 0 percent result in the first row. Investors whose income stays entirely within the 0 percent bracket harvest nothing from long-term losses. The gains they offset were never going to be taxed anyway.

Harvesting short-term losses still works for them, since ordinary rates apply to those dollars.

The 0 percent bracket guide explains that surprise in detail.

Scenario 1: The Rebalancing Investor

Say you hold two tech funds and one has fallen hard. You sell the loser for a $25,000 short-term loss in February and immediately buy a similar, not identical, fund. Earlier that year you had already taken $10,000 of short-term profits from other trades.

The math nets the $25,000 loss against the $10,000 gain, leaving $15,000 of deductible loss. At your 24 percent bracket, the harvest saves $3,600 of federal tax in the current year.

The same trade at the 32 percent bracket would save $4,800 instead. Timing matters as much as the loss itself here.

Investors can even harvest the loss and rebuy a matching ETF the next day, which our ETF tax guide covers. The only trap is the wash sale window, which we flag in every scenario below.

Scenario 2: The Year-End Portfolio Cleanup

December is when most households finally review the whole portfolio. Picture a joint filer with $60,000 of long-term gains from an earlier property stock sale. The portfolio review finds $40,000 of long-term losses across several dud positions.

Netting the two leaves $20,000 of taxable long-term gain instead of $60,000. At the 15 percent rate, the harvest removes $3,000 of federal tax plus a slice of state tax.

Had the losses been short-term, the same cleanup would save more.

Short-term losses cross over and attack the long-term gain at the same 15 percent value.

Elsewhere, those losses might have offset pricier short-term gains. The lesson: match your most expensive losses against your most expensive gains whenever the calendar allows.

Scenario 3: The Big Loss Beyond Any Gains

Some years hand you a loss bigger than the whole market rally. Take a single investor who sells a collapsed growth stock for a $50,000 long-term loss with no gains anywhere. The first $3,000 of the loss offsets ordinary wages this year.

The remaining $47,000 carries forward indefinitely into future tax years. Each future year, another $3,000 offsets ordinary income until the carryover runs out.

The carryover still holds real value, roughly $7,050 at a 15 percent lifetime rate over sixteen years. Future gains get absorbed first, which accelerates the burn through the carryover.

The carryover guide lays out those multi-year rules plus the paperwork involved. Patience turns even a painful loss into a long tax asset.

Adding Your State Tax to the Estimate

State income tax multiplies the savings in most places. The multiplier applies to every bucket in the netting order. A Californian at the top rate saves an extra 13.3 cents per harvested dollar on top of federal savings.

Florida, Texas, and the other zero-tax states add nothing, a point the no-tax states guide covers fully. Some states follow federal loss ordering automatically, while others run separate calculations. Multiply your state rate by the harvested loss for a quick local estimate.

The Wash Sale Check Before You Count Savings

Every calculator estimate dies if the trade triggers a wash sale. The rule has no exception for accidental purchases, so check every account before selling. Repurchasing a matching or near-identical security in the 30 days around the sale cancels the deduction.

The blocked loss moves into the new purchase's basis instead of vanishing entirely. Our wash sale rule guide lists the traps, including dividend reinvestment plans and spousal accounts. Swap into a different index or fund family and the loss stays deductible.

Settlement timing adds one more wrinkle under the T+1 system that took effect in 2024. The shorter cycle mainly matters for trades placed in the final days of December.

Trades now settle the next business day, but the 30-day window still counts calendar days around the trade date. Our T+1 deadline guide maps the exact dates for year-end trades.

A Simple Worksheet You Can Run Today

Copy this worksheet with your own numbers for a solid estimate in ten minutes. Keep each line separate so the tax code's ordering stays intact.

Line I is the number a tax loss harvesting calculator would show you. Combine the federal rate on each bucket with your state rate for the full picture.

A large line H on the worksheet tells its own story. That number represents multi-year carryover value rather than a one-year refund.

Estimating Mistakes That Cost Real Money

First, remember the 3.8 percent NIIT if your income crosses the thresholds. The gains you cancel were carrying that surtax too. Second, remember that harvesting within an IRA does nothing, since retirement accounts already escape capital gains tax.

Third, avoid selling winners just to absorb a small loss. The rate mismatch between the two sides can backfire.

Fourth, watch mutual fund distributions in December, which can quietly undo a harvest inside a taxable fund. Careful sequencing keeps the savings you calculated on paper intact.

The Bottom Line on Harvesting Calculations

A tax loss harvesting calculation is arithmetic once you know your bracket and your netting order. Short-term losses save the most, and long-term losses save 15 or 20 percent. A low-income year can blunt the whole exercise through the 0 percent bracket.

Run the worksheet above before December, mind the wash sale window, and let carryovers work across years. Investors who harvest methodically often save thousands per downturn without changing their portfolio strategy at all.

When Harvesting Pays the Most

The calculator numbers reveal the ideal harvesting conditions. High earners holding both kinds of short-term transactions sit at the top of the savings table. Investors in high-tax states multiply every federal dollar saved.

Volatile markets create the raw material, because losses only exist when positions drop below basis. Combine all three conditions and a single harvest can save four figures in an afternoon of trading.

The worst conditions also show up clearly in the math. Investors inside the 0 percent bracket gain nothing from long-term harvesting. The NIIT also stays out of the picture below its income thresholds.

Holding everything inside retirement accounts removes the strategy entirely. These households should focus on deferral strategies instead of loss harvesting.

Putting a Dollar Value on Carryovers

Carryover losses are an asset you can price like anything else on your balance sheet. A $30,000 carryover offsets $3,000 of ordinary income annually, worth about $720 per year at the 24 percent bracket. Future capital gains burn through it faster and at capital gains rates instead.

If you expect regular gains, the carryover might disappear within a few years. Track it every year when you file, because Form 1040's Schedule D worksheets carry the balance forward automatically.

Using Our Calculator Instead of the Worksheet

The manual worksheet teaches the mechanics, but software does the same math in seconds. Our capital gains calculator handles the netting order automatically and applies the correct 2026 brackets by filing status. Enter each sale with its holding period and basis, and the tool sorts every dollar into the right bucket.

The output shows federal tax, the NIIT line when it applies, and your marginal rate on the next gain. Broker tax tools run similar logic from your actual 1099-B data, which saves the typing. Our 1099-B explainer shows where those numbers come from.

Automated tools share one weakness with manual math. They cannot see trades you plan to make before December 31, so your future sales still need the worksheet. Run the calculation twice each year, once mid-summer and once in early December.

That rhythm catches losses while you can still act on them. It also keeps the wash sale window clean. Investors who check twice a year rarely face a surprise bill when April arrives.