Tax-loss harvesting, without the headache

Nobody enjoys looking at a red position. But a loss you’re already sitting on has one redeeming feature: handled right, it can lower your tax bill. That’s the whole idea behind tax-loss harvesting, and it’s one of the few genuinely free lunches in investing — a way to salvage value from a mistake without needing to be right about anything.

The concept is simple. The execution has exactly one landmine, and it catches almost everyone the first time. Let’s cover both.

The basic move

When you sell an investment for less than you paid, you realize a capital loss. That loss isn’t just a bummer — it’s a deduction. You can use it to:

1. Offset capital gains. Sold a winner this year for a $5,000 gain? Realize a $5,000 loss elsewhere and you’ve cancelled the tax on it.
2. Offset ordinary income, up to a limit. In the US, if your losses exceed your gains, you can deduct up to $3,000 of the excess against regular income each year.
3. Carry the rest forward. Losses beyond that don’t vanish — they roll into future years indefinitely until you use them up.

So a position that’s down $8,000 isn’t only a paper loss. It’s potentially $8,000 of gains you can shelter, or years of $3,000 income deductions, or some blend. You’re converting a bad pick into a smaller tax bill.

The landmine: the wash-sale rule

Here’s where people get burned, and it’s worth reading twice.

If you sell for a loss and buy the same or a “substantially identical” security within 30 days — before or after the sale — the IRS disallows the loss. This is the wash-sale rule, and it exists precisely to stop people from selling for the tax break at 10:00 and buying back at 10:01 to keep their position.

The 30-day window is a 61-day minefield in practice: 30 days before, the day of, and 30 days after. A few things people don’t realize:

• It applies across all your accounts, including your IRA. Selling at a loss in your brokerage and rebuying in your retirement account still triggers it.
• Automatic dividend reinvestment can trip it silently. If a fund you “harvested” reinvests a dividend into more shares inside that window, congratulations, you’ve partially washed your own sale.
• Buying more of the losing stock right before you harvest counts too.

Break the rule and the disallowed loss isn’t gone forever — it gets added to the cost basis of the replacement shares. But you lose the deduction this year, which is usually the entire reason you did it.

Staying invested while you harvest

The obvious worry: “If I sell to harvest the loss, I’m out of the market for 30 days. What if it rips higher without me?”

Fair concern, and there’s a standard workaround. You sell the loser and, instead of sitting in cash, buy something similar but not substantially identical. Sell one S&P 500 fund, buy a different provider’s S&P 500 fund. Sell a specific bank stock, rotate into a broad financials ETF for a month. You keep roughly the exposure you wanted while the calendar clears, then you’re free to switch back after 30 days if you like.

“Substantially identical” is a genuinely fuzzy line the IRS has never fully defined, so the game is to be clearly different, not clever-lawyer different.

When harvesting isn’t worth it

It’s not always the move, and chasing it religiously wastes time and racks up trading friction:

• In a tax-advantaged account. Inside an IRA or 401(k), gains and losses don’t have annual tax consequences. There’s nothing to harvest.
• When the loss is tiny. Harvesting a $60 loss to save maybe $15 in tax, while paying spreads and burning an afternoon, is a hobby, not a strategy.
• When you’d be selling something you want to keep forever anyway. If the thesis is intact and you have no gains to offset, sometimes the cleanest thing is to just… hold it and move on.

The strongest time to harvest is late in the year, once you can see your realized gains for the year and know exactly how much loss is actually useful to book.

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Tradune surfaces harvestable losses across your holdings with the estimated dollar impact attached, so you can see which red positions are actually worth acting on — and which aren’t. It’s a heads-up, not tax advice; for anything involving your specific return, loop in a tax professional.