Crypto tax-loss harvesting, explained

You bought a coin at $4,000. It's worth $1,500 now, and you've mostly made your peace with that. Here's the part people miss. Sell it, and that $2,500 loss becomes a number the IRS lets you subtract from your gains, and sometimes from your paycheck income too. That's all tax-loss harvesting is. You turn a paper loss into a real one on purpose, in a year when it can lower what you owe.

The mechanics are worth getting right, because a few small choices change how much you actually save. Let's walk through them the way you'd hit them doing your own return.

How a loss actually lowers your tax bill

The IRS treats crypto as property. Every time you sell it, trade it for another token, or spend it, you have a taxable disposal, and you end up with a capital gain or a capital loss depending on whether you're above or below what you paid. Buying and holding does nothing. The loss only exists once you dispose of the coin.

Once you have losses, they get used in a set order. First they cancel your capital gains for the year, dollar for dollar. Sold one coin for a $5,000 gain and another for a $5,000 loss? They wipe each other out and you owe nothing on that pair. If your losses are bigger than your gains, up to $3,000 of the leftover comes off your ordinary income, the wages-and-interest kind. Still more after that? It carries forward to future years with no expiration.

Short-term and long-term losses get matched up inside their own groups first, which matters. Short-term gains, on coins held a year or less, are taxed at your regular income rate. Long-term gains get the friendlier 0, 15, or 20 percent. A loss that kills a short-term gain does more work than one killing a long-term gain, so if you can point your losses at your short-term winners, do it.

Which coins you sell changes the number

Say you bought Ethereum three separate times: some at $1,800, some at $3,500, some at $4,200. Now it's $2,000 and you want to sell a chunk. Which batch did you sell? You get to decide, and the answer moves your loss a lot.

That decision is called your lot method. The default is FIFO, first in first out, which sells your oldest coins first. But you can use specific identification, meaning you point at the exact lot you want to sell, as long as your records can back it up. A common flavor is HIFO, highest in first out, which sells your most expensive coins first to book the biggest loss now.

• FIFO sells your earliest purchase first. Simple, and often not the most tax-friendly if your oldest coins are your cheapest.
• Specific ID lets you hand-pick the $4,200 lot so you realize a real loss instead of a gain on the $1,800 lot.
• HIFO is specific ID run on autopilot toward the highest cost basis, which front-loads your losses.

You don't get specific ID for free. You need records showing the date, cost, and quantity of the exact units you sold, ideally captured at the time of the sale. Good crypto tax software handles this. A shoebox of screenshots does not.

The wash-sale gap, and why it might close

With stocks, if you sell at a loss and buy the same thing back within 30 days, the wash-sale rule blocks the loss. You can't claim it that year. Crypto is property, not a security, so that rule doesn't apply to it right now. You can sell Bitcoin at a loss at 2:00 and buy it back at 2:05, lock in the loss for your taxes, and keep your position.

That gap is real and people use it a lot. It may also be on borrowed time. A 2025 White House report suggested treating crypto more like securities, and a congressional discussion draft has floated applying wash-sale rules to digital assets. Nothing has passed. But this is the kind of loophole that tends to get closed, so treat today's freedom as today's, not a permanent feature.

One more caution even under current rules. If you sell and rebuy at a higher price later, you've reset your cost basis higher, which can mean a bigger taxable gain down the road. Harvesting a loss now can borrow from your future self. That's fine if you know you're doing it.

When to do it, and what to file

Harvesting is a calendar-year game. A loss counts for the year you sell, so the deadline is December 31, not April. If you're staring at a big gain from earlier in the year, late December is when you dig through your wallets for underwater positions to sell against it. Waiting until you file is too late. The trade has to happen inside the tax year.

When you do file, each disposal goes on Form 8949, with your cost, your proceeds, and the resulting gain or loss. Those totals flow to Schedule D. And yes, you answer the digital-asset question near the top of your Form 1040 honestly, even in a year you only had losses.

One thing that's new for the 2025 tax year: exchanges are starting to send Form 1099-DA, a broker form for digital assets. For 2025 activity it mostly reports your gross proceeds, not your cost basis, with basis reporting phasing in for coins bought on or after January 1, 2026. So the IRS may see what you sold for without seeing what you paid. If your own records show a loss, that gap is exactly why you keep them. Reconcile the 1099-DA against your real numbers rather than trust it to tell the whole story.

If your holdings are scattered across a few exchanges and a wallet or two, the math gets fiddly fast, and a wrong lot choice can quietly cost you a few hundred dollars. That's the point where a second set of eyes usually pays for itself.