Tax-Loss Harvesting: How to Turn Investment Losses Into Tax Savings
How Tax-Loss Harvesting Works
The concept is straightforward: you sell an investment that’s declined in value, lock in the loss for tax purposes, then reinvest the proceeds in a similar (but not identical) asset. Your portfolio stays on track, but you’ve created a tax deduction.
Here’s the sequence:
| Step | Action | Example |
|---|---|---|
| 1. Identify | Find positions trading below your cost basis | You bought Stock A at $100, now trading at $70 |
| 2. Sell | Sell the losing position to realize the loss | Sell Stock A, realizing a $30 loss |
| 3. Replace | Buy a similar but not “substantially identical” asset | Buy an ETF in the same sector |
| 4. Claim | Use the loss to offset gains on your tax return | $30 loss offsets $30 of capital gains |
The Math Behind Tax-Loss Harvesting
If you harvest $10,000 in losses and your combined federal + state marginal rate is 35%, that’s $3,500 in tax savings. Over a lifetime of investing, these savings compound significantly — especially if you reinvest what you would have paid in taxes.
Offsetting Rules: The Netting Process
The IRS requires you to net gains and losses in a specific order:
| Priority | Rule | Details |
|---|---|---|
| First | Net short-term gains against short-term losses | Within the same holding period category |
| Second | Net long-term gains against long-term losses | Within the same holding period category |
| Third | Net remaining gains/losses across categories | Short-term losses can offset long-term gains and vice versa |
| Fourth | Deduct up to $3,000 against ordinary income | $1,500 if married filing separately |
| Fifth | Carry forward any remaining losses | No expiration — losses carry forward until used |
The Wash Sale Rule
This is the biggest trap in tax-loss harvesting. The wash sale rule says if you buy a “substantially identical” security within 30 days before or after the sale, the IRS disallows the loss. The 61-day window catches investors who try to sell and immediately repurchase.
What counts as “substantially identical”:
| Triggers Wash Sale | Does NOT Trigger Wash Sale |
|---|---|
| Buying the same stock back within 30 days | Buying a different company in the same sector |
| Buying an option on the same stock | Buying an ETF tracking a different index |
| Buying in a different account (IRA, spouse) | Switching from S&P 500 ETF to total market ETF |
| Reinvesting via DRIP in the same security | Waiting 31+ days to repurchase the same security |
Tax-Loss Harvesting Strategies
Year-End Harvesting
The traditional approach: review your portfolio in November/December, identify losing positions, and harvest before year-end. Simple but you might miss opportunities earlier in the year.
Ongoing Harvesting
Check for harvesting opportunities throughout the year — especially during market dips. A 10% market correction creates harvesting opportunities across many positions. This is what robo-advisors like Wealthfront and Betterment do automatically.
Asset Location Strategy
Keep tax-inefficient investments (bonds, REITs) in tax-advantaged accounts, and hold equities in taxable accounts where you can harvest losses. This maximizes your harvesting opportunities.
When Tax-Loss Harvesting Makes Sense
| Factor | Good Candidate | Poor Candidate |
|---|---|---|
| Tax Bracket | High earners (32%+ bracket) | 0% capital gains bracket |
| Portfolio Size | $100K+ taxable portfolio | Small portfolios (savings minimal) |
| Realized Gains | Large gains to offset this year | No gains to offset |
| Time Horizon | Long-term investor | Frequent trader (already short-term) |
| Account Type | Taxable brokerage account | 401(k) or IRA (already tax-sheltered) |
Common Mistakes to Avoid
Selling just for the tax benefit. Don’t harvest a loss if it means abandoning a position you still believe in long-term without a good replacement asset. The tax tail shouldn’t wag the investment dog.
Forgetting about state taxes. Harvesting saves on both federal and state taxes. In high-tax states like California or New York, the combined savings can be substantial.
Ignoring transaction costs. With most brokerages now commission-free, this is less of a concern — but watch for bid-ask spreads on less liquid securities.
Not tracking cost basis. Your replacement investment inherits the adjusted cost basis. If you harvest a $5,000 loss and reinvest, you’ve lowered your future cost basis — meaning a bigger taxable gain when you eventually sell. Tax-loss harvesting defers taxes, it doesn’t eliminate them (unless you donate the shares or pass them on at death with a stepped-up basis).
Key Takeaways
- Tax-loss harvesting offsets capital gains and up to $3,000 of ordinary income annually, with unlimited carryforward.
- Respect the wash sale rule: no repurchasing “substantially identical” securities within 30 days before or after the sale.
- Short-term losses are more valuable than long-term losses because they offset higher-taxed short-term gains first.
- Harvesting is most effective for high-income investors with large taxable portfolios and significant realized gains.
- The strategy defers taxes rather than eliminating them — but deferral is still valuable because of the time value of money.
Frequently Asked Questions
Is tax-loss harvesting worth it for small portfolios?
It depends on your tax bracket and the size of the losses. If you’re in the 22%+ bracket and can harvest even $5,000 in losses, that’s $1,100+ in savings. With commission-free trading, there’s little cost to trying — just be mindful of the wash sale rule.
Can I tax-loss harvest in my IRA or 401(k)?
No. Tax-loss harvesting only works in taxable brokerage accounts. IRAs, 401(k)s, and other tax-advantaged accounts are already tax-sheltered, so selling at a loss doesn’t create a deductible loss.
Does tax-loss harvesting actually save money, or just defer taxes?
Primarily it defers taxes by lowering your cost basis on replacement investments. However, it can permanently save money if you’re in a lower bracket when you eventually sell, if you donate the shares, or if your heirs inherit with a stepped-up basis. The deferral itself also has value — money not paid in taxes today can compound for you.
How often should I check for tax-loss harvesting opportunities?
At minimum, do a year-end review. Ideally, monitor throughout the year — market dips create the best opportunities. Many robo-advisors scan daily. Quarterly reviews are a practical middle ground for DIY investors.
What happens to harvested losses I can’t use this year?
They carry forward indefinitely. If you harvest $50,000 in losses but only have $10,000 in gains, you offset the gains, deduct $3,000 against ordinary income, and carry $37,000 forward. Those losses remain available to offset future gains for as long as it takes to use them up.