Tax Loss Harvesting Assistant
Calculate tax savings from selling an investment at a loss: gains offset, the $3,000 ordinary income deduction, carryforward and net benefit after costs.
Tax Loss Harvesting Assistant
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Formula: Tax Savings = (Loss Offsetting Gains x CG Rate) + (min(Remaining, $3000) x Income Rate)
Worked example — Harvest recommended | Immediate savings: $3,120 | Carryforward: $2,000 (1 year)
Formula
Tax Savings = (Loss Offsetting Gains x CG Rate) + (min(Remaining, $3000) x Income Rate)
Realized losses first offset capital gains dollar-for-dollar at the applicable capital gains rate. Remaining losses offset up to $3,000 of ordinary income at your marginal tax rate. Any excess carries forward to future years. The net benefit subtracts estimated transaction costs from immediate tax savings.
Worked Examples
Example 1: Offsetting Capital Gains
Problem:You bought stock for $50,000, now worth $35,000. You have $10,000 in realized capital gains this year. You are in the 24% tax bracket, short-term holding.
Solution:Unrealized Loss: $50,000 - $35,000 = $15,000 Gains Offset: min($15,000, $10,000) = $10,000 Tax Savings (gains): $10,000 x 24% = $2,400 Remaining Loss: $15,000 - $10,000 = $5,000 Ordinary Income Offset: min($5,000, $3,000) = $3,000 Tax Savings (income): $3,000 x 24% = $720 Carryforward: $5,000 - $3,000 = $2,000 Immediate Savings: $2,400 + $720 = $3,120
Result:Harvest recommended | Immediate savings: $3,120 | Carryforward: $2,000 (1 year)
Example 2: Small Loss with No Gains to Offset
Problem:You bought a fund for $20,000, now worth $18,000. No capital gains this year. 32% tax bracket, long-term holding.
Solution:Unrealized Loss: $20,000 - $18,000 = $2,000 Gains Offset: $0 (no gains) Ordinary Income Offset: min($2,000, $3,000) = $2,000 Tax Savings: $2,000 x 32% = $640 Transaction Cost: $18,000 x 0.2% = $36 Net Benefit: $640 - $36 = $604
Result:Harvest recommended | Net benefit: $604 | Loss applied to ordinary income
Frequently Asked Questions
What is tax-loss harvesting and how does it work?
Tax-loss harvesting is the practice of selling investments at a loss to offset capital gains taxes. When you sell a losing position, the realized loss can be used to reduce your taxable gains dollar-for-dollar. If losses exceed gains, up to $3,000 per year ($1,500 if married filing separately) can offset ordinary income. Any remaining losses carry forward indefinitely to future tax years. The strategy works best when you immediately reinvest in a similar (but not substantially identical) asset, maintaining your market exposure while capturing the tax benefit. This effectively provides a government-subsidized discount on your investment losses.
What is the wash sale rule?
The wash sale rule (IRS Section 1091) disallows the tax deduction if you purchase a substantially identical security within 30 days before or after the sale. This 61-day window (30 days before + sale date + 30 days after) prevents investors from selling for a tax loss and immediately rebuying the same investment. The rule applies across all accounts including IRAs and spouse accounts. To maintain market exposure, investors typically buy a similar but not identical fund (e.g., switching from one S&P 500 fund to another tracking a different index). Violating the wash sale rule does not lose the loss permanently; instead, it is added to the cost basis of the replacement shares.
When is tax-loss harvesting most beneficial?
Tax-loss harvesting provides the greatest benefit in these situations: when you have significant realized capital gains to offset (from selling appreciated stocks, mutual fund distributions, or business sales), when you are in a high tax bracket (24%+ federal), when losses are substantial enough that the tax savings exceed transaction costs, and when you can maintain equivalent market exposure through substitute investments. The strategy is particularly valuable in volatile markets where temporary paper losses can be converted to real tax benefits. Year-end is the most common time, but opportunities arise throughout the year. High-income investors in the 37% bracket save $0.37 per dollar of short-term loss harvested.
How does the $3,000 ordinary income deduction work?
After offsetting all capital gains, excess net capital losses can reduce your ordinary income by up to $3,000 per year ($1,500 if married filing separately). This is valuable because it reduces income taxed at your marginal rate. For someone in the 32% bracket, $3,000 saves $960 in federal taxes. Any losses beyond $3,000 carry forward to future years indefinitely, maintaining their full value. The carried-forward losses first offset future capital gains, then provide the $3,000 annual deduction. For large losses, this means years of tax benefits: a $30,000 excess loss would provide $3,000 deductions for 10 years if no capital gains arise.
What are the risks and downsides of tax-loss harvesting?
While generally beneficial, tax-loss harvesting has some caveats. Transaction costs (commissions, bid-ask spreads) reduce the net benefit, though with commission-free trading this is minimal. If you violate the wash sale rule, you lose the current deduction. The new lower cost basis means larger gains when you eventually sell, so tax-loss harvesting defers taxes rather than eliminating them entirely (unless you donate the shares or hold until death for a stepped-up basis). Frequent trading creates complexity at tax time and requires careful record keeping. The strategy also requires discipline to sell losing positions, which can be psychologically difficult. Finally, if your tax bracket changes significantly in the future, the deferred benefit may be at a different rate.
In what order are short-term and long-term losses netted?
Schedule D nets within each bucket before the buckets meet: short-term gains against short-term losses, long-term gains against long-term losses. Only if one bucket ends net negative does it offset the other. That ordering is why a short-term loss is usually the more valuable one to harvest — it first shelters short-term gains taxed at ordinary rates, whereas a long-term loss first meets gains taxed at preferential rates. Tax Loss Harvesting Assistant applies a simplified version of that netting, so confirm the actual sequence for your return.
Why does the cost basis method matter when harvesting a loss?
A position bought in several tranches contains lots with different basis and different holding periods. Under specific identification you tell the broker exactly which shares to sell, letting you realise the largest loss or the holding period you want. Default methods do this for you: first-in-first-out sells the oldest lots, and average cost, common for mutual funds, blends basis so individual lots cannot be targeted. The election generally must be made at or before settlement, so choosing lots afterwards is not available.
Why is there nothing to harvest inside an IRA or 401(k)?
Tax-deferred and tax-free accounts do not report capital gains or losses on your return, so selling a depreciated holding inside one produces no deduction. Worse, purchases in an IRA can trigger the wash sale rule against a loss you realised in a taxable account, and in that case the disallowed loss is not restored to the IRA's basis, so it is lost rather than deferred. Harvesting is therefore a taxable-account technique, and replacement buys should be coordinated across every account you and your spouse control.
What counts as substantially identical, and how do investors stay invested during the wash-sale window?
The statute does not enumerate the term, and the conservative reading is that the same security, or a fund tracking the same index, is at risk of being treated as identical. The usual practice is to move into a different fund with similar but distinct exposure — a different index or a different provider's broad-market product — so the portfolio's risk profile survives the 61-day window around the sale. Because the boundary is a judgement call rather than a bright line, this is a point to check with a tax professional.
Does a carried-forward loss keep its short-term or long-term character?
Yes. An unused net capital loss carries forward retaining the character it had when realised, so a short-term carryforward continues to offset short-term gains first in later years, and likewise for long-term. Carryforwards do not expire for individuals, and each year they first absorb capital gains before the limited deduction against ordinary income applies. Because the value of a carryforward depends on your future rates and gains, a large one may take many years to be used at full value.
References
Background & Theory
History
Reviewed for accuracy by Daniel Agrici, Founder & Lead Developer · Editorial policy
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