How Tax-Loss Harvesting Works, and Where High Earners Go Wrong
If you are holding an investment that is down this year, you have until December 31 to turn that paper loss into something useful on your tax return. After the calendar flips, the opportunity for the current year is gone. That deadline is why tax-loss harvesting shows up on every year-end planning checklist, and also partly why it is also one of the easiest strategies to get wrong.
Tax-loss harvesting is the practice of selling an investment that has fallen below the price you paid for it, then using the realized loss to offset capital gains elsewhere in your portfolio. If your losses are larger than your gains, you can deduct up to $3,000 of the excess against your ordinary income for the year ($1,500 if you are married filing separately), and carry anything left over into future years with no expiration.
That sounds simple, and the core concept is. The trouble starts with all the rules around it, and those rules trip up exactly the people who have the most to gain: high earners with concentrated stock, vested equity, and automatic reinvestment running in the background. Here is how the mechanics work, where the traps are, and when harvesting is actually worth doing.
What Does a Harvested Loss Actually Offset?
A realized capital loss offsets your capital gains first, in a specific order, before it touches anything else. Short-term losses net against short-term gains, long-term losses against long-term gains, and then the two categories net against each other. Only after all of that does up to $3,000 of any remaining loss come off your ordinary income. Whatever is still left carries forward indefinitely to future tax years.
The order matters more for high earners than most people realize, because short-term gains are taxed as ordinary income. If you have short-term gains from selling vested RSUs or rebalancing a taxable account, a harvested loss applied against those gains offsets income taxed at your full marginal rate, which for a household in the top brackets can approach 37% federal before state tax. A loss applied against long-term gains offsets income taxed at 15% or 20%.
There is a second layer that catches investors above certain income levels. Once your modified adjusted gross income passes $200,000 (single) or $250,000 (married filing jointly), a 3.8% net investment income tax can apply to your investment income under Section 1411. That surtax turns a 15% long-term capital gains rate into 18.8%, and a 20% rate into 23.8%. A harvested loss that offsets gains in that range is also peeling back the 3.8%, which is part of why the strategy tends to be worth more to high earners than the headline rates suggest.
One caveat - Harvesting a loss against a long-term gain is often tax deferral, not permanent savings. When you sell the replacement investment later, your lower cost basis means a larger gain down the road. The benefit comes from the time value of deferring the tax, converting a future long-term gain into a current offset against higher-taxed income, and from the $3,000 annual deduction against ordinary income. It is better understood as a timing tool than a free lunch.
What Is the Wash-Sale Rule, and How Do You Trigger It by Accident?
The wash-sale rule disallows your loss if you buy a substantially identical security within 30 days before or after the sale that created it. That is a 61-day window centered on the sale date, not just the 30 days after. When it applies, you do not lose the loss outright. It gets added to the cost basis of the replacement shares, so you recover it when you eventually sell those. The actual rule is in Section 1091, and the SEC describes it in plain terms on its investor education site, investor.gov.
The reason this rule catches high earners specifically is that many of them are buying their own company stock automatically, without thinking of it as a purchase. A few ways it happens:
Your RSUs vest within the window. Vesting purchases and delivers you the shares, and the IRS treats that as acquiring stock. If you sell the same company stock at a loss in your taxable account and have a vesting event 15 days later, you may have a wash sale on your hands without even knowing it.
Your ESPP buys shares on its scheduled purchase date. Employee stock purchase plans run on a fixed calendar you do not control, and that purchase counts too.
Dividend reinvestment buys more shares on its own. If a fund or stock you just sold at a loss reinvests a dividend into new shares during the window, that fraction of your loss is washed.
The trap with the sharpest edge involves your IRA. If you sell at a loss in your brokerage account and buy the substantially identical security in your traditional or Roth IRA within the window, the IRS disallowed the loss in Revenue Ruling 2008-5, and because the replacement sits in an IRA, the basis adjustment does not help you. The loss is not deferred. It is gone for good. The rule also reaches across to a spouse's accounts and to entities you control, so coordinating within a household matters.
When Does Harvesting Help, and When Does It Not?
Harvesting helps most when you have realized gains to offset or a high ordinary-income rate that makes the $3,000 deduction and the carryforward worth capturing. It does the least when your income is unusually low in a given year, when you would already qualify for the 0% long-term capital gains rate, or when the trade costs and the basis reduction outweigh a small loss.
Consider a hypothetical. Imagine Stephanie, a software engineer four years into a company whose stock has slid this year with the tech stock correction. She has ~$40,000 of unrealized losses in shares she bought through past vesting, and she also took ~$25,000 of short-term gains earlier in the year when she sold some prior vested RSUs to diversify. Her household income is around $320,000, which puts her above the net investment income tax thresholds. If she harvests the $40,000 loss, it can wipe out the $25,000 short-term gain (taxed at her ordinary rate plus the 3.8% surtax), and $3,000 of the remaining $15,000 would come off her ordinary income this year. The last $12,000 would carry forward indefinitely, first offsetting future capital gains and then up to $3,000 offsetting ordinary income each year. The outcome depends on her full tax picture, but the loss is working at her highest rates rather than sitting idle.
The part Stephanie has to watch is her vesting schedule. If more of her RSUs vest within 30 days of the sale, she risks washing part of that loss. This is where the strategy fails when viewed in a silo.
At Lotus, equity compensation planning is one of the areas where we spend the most time with clients, because the sale, the vesting calendar, the ESPP purchase dates, and the reinvestment settings all have to be looked at together before a single share is sold.
What Does a Clean Year-End Sequence Look Like?
Start by pulling your realized gains and losses for the year so far, then your unrealized positions, so you know what you are working with before you trade. Identify which losing positions you actually want out of, and check every channel that could be buying the same security: vesting dates, ESPP purchase windows, and dividend reinvestment settings inside the 61-day window. If you want to stay invested in the market while the clock runs, some investors move the proceeds into a related but not substantially identical holding, for example a broad index fund in place of a single stock, so they keep exposure without repurchasing the identical position. Then document each sale, because these transactions land on Form 8949 and Schedule D when you file.
In our experience working with clients at Lotus, the ones who approach harvesting most effectively are those who look at it throughout the year, not the ones scrambling in the last week of December when vesting events and fund distributions are hitting all at once. And this is something we do on behalf of clients throughout the year, because let’s face it - high earners are too busy to coordinate all of this effectively.
The Takeaways
Tax-loss harvesting can lower your tax bill (sometimes meaningfully), but how much depends on your gains, your income, your filing status, and your timing. The strategy tends to be most valuable to high earners because losses can offset ordinary-rate short-term gains and peel back the 3.8% surtax, and least valuable when your income is low or your loss is small. The biggest mistake is accidentally repurchasing the same security through vesting, an ESPP, an IRA, or reinvested dividends, which can disallow the loss you were trying to capture. Similar issues arise from trying to time markets within the 61-day window, where volatility can quickly erase and tax-efficiency you tried to create.
If you are holding positions that are underwater and you also have equity vesting on a schedule, the two need to be looked at together before year-end. If any of this applies to your situation, it is worth a conversation with your advisor before December 31.
FAQ
Q: Does the wash-sale rule apply if I buy the same stock back in my IRA?
A: Yes, and this is the version of the rule with the worst outcome. If you sell a security at a loss in your taxable account and buy the substantially identical security in your traditional or Roth IRA within 30 days before or after, the IRS disallows the loss under Revenue Ruling 2008-5. Because the replacement shares are inside an IRA, you do not get the usual basis adjustment, so the loss is permanently lost rather than just deferred.
Q: Can I harvest a loss and still stay invested in the market?
A: Generally yes. The wash-sale rule only disallows the loss if you buy back something substantially identical within the 61-day window. Some investors sell the losing position and move the proceeds into a related but not substantially identical investment, which keeps them exposed to the market while avoiding a repurchase of the same security. What counts as substantially identical can be a judgment call, so it is worth confirming before you trade.
Q: Is tax-loss harvesting worth it if I only have a small loss?
A: It depends on your situation. A small loss can still be useful if you have short-term gains to offset or you can take the $3,000 deduction against ordinary income. But if the loss is tiny, if trading costs eat into it, or if you would already pay a 0% rate on your gains, the effort may not be worth it. The benefit scales with your income and the size of the loss, not the act of harvesting itself.
