Tax‑loss harvesting (also called tax‑loss selling) is the deliberate sale of investments at a loss to reduce the investor’s taxable capital gains or to offset ordinary income (up to an annual limit). You realize a capital loss on a security, use that loss to offset realized capital gains of the same tax year (and then to offset other gains or income within IRS limits), and—if desired—replace the sold holding with a similar (but not “substantially identical”) investment so your portfolio’s risk and allocation stay close to the original.
Key benefits
– Lowers capital gains tax in the current year by offsetting gains with realized losses.
– Allows limited offset against ordinary income if losses exceed gains (see limits below).
– Preserves overall portfolio strategy if replacement holdings are chosen carefully.
How Tax‑Loss Harvesting Works (conceptual)
1. Identify investments with unrealized losses.
2. Sell the loss positions to “realize” the loss for tax reporting.
3. Use the realized losses to offset realized capital gains of the same year (short‑term losses first against short‑term gains, long‑term losses first against long‑term gains; netting rules apply).
4. If losses exceed gains, use up to $3,000 ($1,500 if married filing separately in most years) of net capital loss to reduce ordinary income; carry forward any remaining loss to future years.
5. Replace the sold security with a non‑substantially identical investment to keep your asset mix while avoiding the wash‑sale rule.
Practical step‑by‑step guide
1. Inventory your portfolio and realized gains for the year
• Pull year‑to‑date trade history and current unrealized gains/losses.
• Separate short‑term (assets held one year or less) and long‑term (held more than one year) positions.
2. Prioritize candidates for harvesting
• Look for underperforming holdings you no longer want or that you can replace with similar exposure.
• Prioritize realizing short‑term losses (they offset short‑term gains taxed at higher ordinary rates).
• Consider tax brackets: losses are more valuable if they offset gains taxed at high marginal rates.
3. Check the wash‑sale rule before executing
• Do not buy a “substantially identical” security within 30 days before or after the sale (61‑day window centered on the sale date).
• If the wash‑sale rule is triggered, the tax loss is disallowed and is added to the basis of the replacement security.
4. Execute the sale
• Sell the loss positions. If you want similar exposure, buy a replacement that is not substantially identical (for example, a different ETF tracking the same index, or a mutual fund with different issuer/strategy).
5. Record and report
• Save trade confirmations. Report transactions on Form 8949 and Schedule D of Form 1040.
• If a wash sale is disallowed, report that adjustment on Form 8949 (the broker will often report wash sales on your 1099‑B).
6. Monitor and adjust
• Track carryforwards of unused losses.
• Reevaluate demonstrated portfolio drift, transaction costs, and tax impact in subsequent years.
Example (illustrative)
Assume you realized:
– Short‑term gain: $8,000 (taxed at your ordinary marginal tax rate).
– Long‑term gain: $20,000 (taxed at long‑term rates).
You also have unrealized losses of $25,000 in other holdings.
If you harvest the $25,000 of losses and apply them:
– Short‑term gains are offset first by short‑term losses; long‑term likewise. But ultimately you net across categories. Net result: $28,000 net losses against $28,000 of gains leaves $0 taxable gain, and $17,000 of losses remaining ($25k realized − $8k short‑term − $20k long‑term = net −$3k? — see ordering rules below). The practical effect is you eliminate tax on the realized gains and can use up to $3,000 of remaining net loss to reduce ordinary income this year; any excess carries forward.
Notes on ordering and calculation
– Short‑term losses first offset short‑term gains; long‑term against long‑term. After those pairings, any remaining long‑term losses can offset the other type of gain. The net result is a single net capital gain or loss for the year.
– If net capital loss remains after offsetting gains, you may deduct up to $3,000 of that net loss against ordinary income per year (or $1,500 if married filing separately); the remainder carries forward indefinitely.
The wash‑sale rule: what it is and why it matters
– Definition: A wash sale occurs when you sell a security at a loss and buy a “substantially identical” security within 30 days before or after the sale. If a wash sale occurs, the loss is disallowed for current tax reporting. Instead, the disallowed loss is added to the tax basis of the replacement security, effectively postponing—not eliminating—the loss until the replacement is sold.
– Practical implication: To capture an immediate tax benefit from a harvested loss, avoid purchasing the same or substantially identical security within the 61‑day window surrounding the sale date.
– Examples: Selling one S&P 500 ETF and immediately buying another S&P 500 ETF from a different issuer may be acceptable (many practitioners treat funds tracking the same index as not “substantially identical” for wash‑sale purposes, although the IRS gives no exhaustive list). Selling a single company’s stock and buying call options on that same company or a derivative tied directly to that stock is likely a wash sale.
– If you accidentally trigger a wash sale, the loss is not permanently lost — it is added to the basis of the replacement position and will affect future gain/loss when that replacement is sold.
What counts as a “substantially identical” security?
– The IRS hasn’t published a bright‑line test. It tends to treat:
• The same company’s stock as substantially identical to itself.
• An option or contract to buy the same security as substantially identical.
• Broadly diversified funds/ETFs that track the same index are often treated as different by investors and many tax pros (e.g., two different Vanguard and iShares S&P 500 ETFs), but there is no definitive IRS list. Use caution and document rationale.
– If clarity matters, consult a tax professional before executing complex replacements.
How much tax‑loss harvesting can you use per year?
– You can use losses to offset capital gains fully, regardless of amount in the year realized.
– If losses exceed gains, you may deduct up to $3,000 of net capital loss against ordinary income on your federal return in most years ($1,500 if married filing separately).
– Any excess net capital loss is carried forward to future tax years (no time limit). (See IRS Topic No. 409 and Publication 550.)
Portfolio maintenance: replacing sold holdings
– Goal: Maintain target asset allocation and risk exposure while respecting tax rules.
– Replacement strategies:
• Buy a similar (but not substantially identical) fund or ETF that tracks a similar index but is managed by a different issuer or uses a different structure.
• Use cash temporarily (risk of being out of market).
• Use inverse or leveraged products carefully — these are usually inappropriate replacements due to different risk/return profiles.
– Balance tax benefit against trading costs, bid/ask spreads, timing risk, and portfolio drift.
Costs, risks, and practical considerations
– Transaction costs and bid/ask spreads may erode tax savings.
– Being out of the market while waiting 31 days to avoid a wash sale risks missing rebounds.
– Harvesting accelerates recognition of losses (defers tax, doesn’t eliminate it) — you may lose future tax benefits if the replacement’s basis increases through a wash‑sale adjustment.
– Frequent trading may complicate recordkeeping and trigger wash sales across accounts (wash sale rule applies across all your taxable accounts, including IRAs). Buying the same security in an IRA within the wash‑sale window can make the loss permanently disallowed.
– Consider overall investment plan, transaction fees, and tax‑bracket effects. For wealthier taxpayers, offsetting gains taxed at 20% or paying the 3.8% net investment income tax can make harvesting more valuable.
When to consider tax‑loss harvesting
– Late in the calendar year: Many investors do a “tax‑loss harvesting sweep” in November–December after assessing realized gains.
– After a large market downturn: More opportunities to harvest losses occur when many holdings are below their cost basis.
– When you have large realized gains to offset, especially short‑term gains taxed at higher rates.
– When you plan to maintain similar market exposure but want tax relief.
Reporting and forms
– Brokers report sales on Form 1099‑B.
– You report sales, disallowed wash sales, and basis adjustments on Form 8949 and summarize on Schedule D of Form 1040.
– Keep careful records of trade dates, cost basis, wash‑sale adjustments, and trade confirmations.
Common mistakes to avoid
– Triggering wash sales unintentionally — across accounts or involving IRAs.
– Focusing on tax savings and ignoring trading costs, bid/ask spreads, or strategy drift.
– Selling winners to avoid taxes without considering long‑term investment goals (tax‑loss harvesting is not a substitute for a disciplined investment plan).
– Assuming ETFs tracking the same index are always safe replacements — while common in practice, the IRS has not set firm rules; document your rationale.
The bottom line
Tax‑loss harvesting can be a useful tool to reduce taxes on realized capital gains, offset ordinary income up to annual limits, and improve after‑tax returns when used prudently. It requires knowledge of short‑ vs long‑term netting rules, the 30‑day wash‑sale rule, and recordkeeping. Weigh the expected tax savings against trading costs, tracking error, and the potential for inadvertently disallowed losses. For complex situations or high dollar amounts, consult a qualified tax advisor or CPA.
Sources and further reading
– Investopedia, “Tax‑Loss Harvesting” (Sydney Saporito) — overview and examples.
– Internal Revenue Service, Topic No. 409, Capital Gains and Losses.
– Internal Revenue Service, Publication 550, Investment Income and Expenses (capital gains/losses and wash‑sale rules).
– Internal Revenue Service, “Federal Income Tax Rates and Brackets” (for marginal and capital gains rates by income).
Editor’s note: The following topics are reserved for upcoming updates and will be expanded with detailed examples and datasets.