How Loss Harvesting Saves You Money
Capital losses offset capital gains dollar-for-dollar. If you have $20,000 of long-term gains and you harvest $15,000 of losses, your net taxable gain is $5,000. At a 15% LTCG rate, you pay $750 instead of $3,000 — a $2,250 savings.
Excess losses (above what's needed to offset gains) deduct from ordinary income up to $3,000 per year. So if you have only $5,000 of gains and harvest $20,000 of losses, you offset all $5,000 of gains AND deduct $3,000 against your salary. At a 24% marginal rate, that's $720 of additional savings.
Remaining losses ($12,000 in our example) carry forward indefinitely. Next year, those losses are available to offset future gains and another $3,000 of ordinary income. Carryforwards never expire and stay with you year after year on Schedule D.
Practical example with real numbers: an investor has $1.2 million in taxable accounts. After a market drop, they have $80,000 of unrealized losses across various positions. They harvest $80,000, offsetting $40,000 of gains realized earlier in the year (saving $6,000-$9,500 depending on bracket and NIIT). The remaining $40,000 of losses offsets $3,000 of ordinary income (saving $720-$1,110) and creates a $37,000 carryforward for future years. Total first-year savings: $6,720-$10,610.
Wash Sale Rules: The Trap That Voids Your Loss
The wash sale rule disallows a loss if you buy 'substantially identical' securities within 30 days before OR after the loss sale. The full window is 61 days (30 + day of sale + 30). Violate it and the IRS disallows the loss; the disallowed amount adds to the basis of the replacement shares, deferring (not eliminating) the tax benefit.
What counts as 'substantially identical' is the gray area. Same stock: definitely. Different share class of the same company: probably. Two different S&P 500 index funds (e.g., VOO and SPY): unsettled but generally treated as not substantially identical. Sector ETFs vs broad market ETFs: not substantially identical. Same company's stocks AND options: yes, options on the same stock count.
Real-world workarounds: sell VOO at a loss, buy IVV (iShares S&P 500) for 31 days, then optionally swap back. Sell QQQ at a loss, buy XLK (Tech Select Sector SPDR) for 31 days. Sell individual stocks, buy a sector ETF that includes them but isn't 'substantially identical.' The key is maintaining similar market exposure without violating the 30-day rule.
IRA wash sale trap: selling a stock at a loss in your taxable account and buying the same stock in your IRA within 30 days triggers the wash sale rule with the loss permanently disallowed (no basis carryforward into the IRA, since IRAs use cost basis differently). This is the most expensive way to lose a deduction. Always check IRA holdings before harvesting losses.
Spousal and Joint Account Considerations
Wash sale rules apply across spouses' accounts and across all account types you control. If you sell a stock at a loss in your account and your spouse buys it within 30 days in their separate brokerage account, the wash sale rule still applies — even though the accounts are technically separate.
This is sometimes called the 'related party' rule and extends beyond spouses. It includes accounts you have control over (custodial accounts for children, trusts where you're the trustee), corporations you control, and certain partnerships. The IRS aggregates these accounts to enforce wash sale rules.
Joint accounts are simpler — both spouses are owners of all positions, so there's no separate-account question. Just be aware of the timing across all securities held jointly when planning harvests.
Practical tactic: if you and your spouse both want to maintain similar positions, coordinate harvest timing. One of you can sell and buy a replacement; after 30+ days, you can both swap back to the original if desired. Or use slightly different replacement securities so neither account holds a 'substantially identical' position during the window.
Best Times to Harvest Losses
Year-end (November-December) is the most common harvesting season because that's when investors finalize their tax planning for the year. Losses must be realized by December 31 to count for the current tax year. The rush in late December can create some price pressure on commonly held losers.
Mid-year volatility: 2022's market decline created huge harvesting opportunities throughout the year, not just at year-end. Sophisticated investors harvest losses opportunistically when positions drop 10%+ rather than waiting for December. The earlier you harvest, the longer the carryforward has to compound through future years' offsets.
Tactically, harvest losses in the same year you have realized gains to offset. If you sold an appreciated property in March, plan to harvest losses in December to offset that specific gain rather than letting it carry to a future year when you might not have gains to use the loss against (still useful for $3K ordinary income offset, but offsetting gains is more valuable).
Avoid harvesting when you're below the LTCG 0% bracket. Single filers with taxable income below $48,350 and married couples below $96,700 pay 0% on long-term gains. Realizing losses in those years 'wastes' the loss against gains that wouldn't have been taxed anyway. Save losses for years when your bracket pushes gains into the 15% or 20% rates.
Robo-Advisor Tax-Loss Harvesting
Wealthfront and Betterment popularized automated tax-loss harvesting for retail investors. The robo-advisor monitors holdings daily and automatically harvests losses when positions drop, simultaneously buying a similar (but not substantially identical) replacement to maintain market exposure.
Wealthfront claims 1.50-2.00% additional after-tax return per year from harvesting on a $1M+ portfolio. Independent academic studies have validated benefits in the 0.50-1.50% range for moderate-to-high tax bracket investors. The benefit varies by tax rate, market volatility, and account size — high earners in volatile markets see the most benefit.
Daily-frequency harvesting requires careful coordination of replacement securities. Wealthfront uses algorithms to swap between similar ETFs (Vanguard, iShares, Schwab equivalents) without triggering wash sales. Betterment uses similar logic. Direct indexing (holding individual stocks instead of ETFs) creates more harvesting opportunities because individual stocks are more volatile than diversified ETFs.
Direct indexing services from Wealthfront, Schwab, and Fidelity offer harvesting at the individual stock level — typically requiring $100K-$250K minimums. The benefit is substantially higher harvesting volume because individual stocks have more variance than indexes. Costs: typically 0.25-0.40% management fee, comparable to actively managed ETFs.
When Harvesting Doesn't Help
Tax-deferred accounts (Traditional IRA, 401(k), 403(b)): no harvesting benefit because you don't pay capital gains in these accounts anyway. Withdrawals are taxed as ordinary income regardless of underlying security gains/losses. Don't bother trying to harvest in these accounts.
Tax-free accounts (Roth IRA, Roth 401(k), HSA): no harvesting benefit because all growth is permanently tax-free. The whole point of these accounts is that you never pay capital gains regardless of what happens.
Low-bracket taxpayers (taxable income below $48,350 single / $96,700 MFJ): you're already in the 0% LTCG bracket. Harvesting losses to offset gains that would have been taxed at 0% is mathematically pointless. Save the losses for years when you're in higher brackets.
Short holding periods: if you bought a stock 3 months ago and it's down 20%, harvesting now creates a short-term loss. Short-term losses still help (they offset short-term gains first, then long-term, then $3K ordinary), but if you would have held the position for over a year, you might prefer to wait, harvest as a long-term loss, and use it against long-term gains. The math depends on your specific situation.
Bonds in a rising-rate environment: bond prices fall when rates rise, creating paper losses. Harvesting bond losses can be valuable but watch for unintended consequences — you may not be able to easily reinvest at the same yield, and the wash sale rules apply across similar duration/credit bonds.