Most crypto investors are assigned FIFO (First In, First Out) by default and never think about it again. That default decision can cost thousands of dollars in unnecessary taxes every single year. Here’s how the three main cost basis methods actually work, when each one makes sense, and what the IRS requires you to do if you want to switch.
What Is a Cost Basis Method?
When you sell cryptocurrency, your taxable gain is the difference between your sale price and your cost basis — what you originally paid for the coins you’re selling. If you’ve bought the same coin at different prices over time, you need a rule for determining which coins you’re selling. That rule is your cost basis method.
The IRS allows several methods for cryptocurrency. The most common are FIFO, HIFO, and Specific Identification. Each produces a different taxable gain — sometimes dramatically different.
FIFO: First In, First Out
Under FIFO, the first coins you bought are treated as the first coins you sell. This is the IRS default if you don’t specify otherwise.
When FIFO works in your favor: If the crypto market has gone down since your earliest purchases, FIFO lets you realize a loss on those early high-cost coins. Also, if your oldest holdings are long-term (held over one year), FIFO gives you access to the lower long-term capital gains tax rates.
When FIFO hurts you: In a bull market, your oldest coins likely have the lowest cost basis and the largest gain. Selling those first maximizes your taxable gain when you’d rather sell higher-cost, shorter-term lots instead.
HIFO: Highest In, First Out
Under HIFO, the coins with the highest cost basis are treated as sold first. This minimizes your taxable gain in almost all market conditions because you’re always selling the lots where you paid the most.
When HIFO makes sense: HIFO is typically the best choice for tax minimization in active trading situations, especially when you have a mix of purchase prices and markets have risen. It consistently produces the smallest short-term gain (or largest loss) on each sale.
The catch: HIFO is a form of Specific Identification, which means it requires per-lot tracking and adequate identification. You must be able to document which specific lots you’re selling at the time of the sale. Broad-based HIFO without that documentation is not permitted by the IRS.
Specific Identification (Spec ID)
Specific Identification lets you choose exactly which lots you’re selling — not based on a rule, but based on your strategic selection. You might sell the lot that creates a long-term gain to access the lower tax rate, or sell a high-cost lot to minimize gain, or harvest a specific loss to offset gains elsewhere.
This is the most flexible method and the most powerful tax planning tool. It’s also the most documentation-intensive.
IRS requirements for Spec ID: Per IRS guidance (Rev. Proc. 2024-28 and prior guidance), you must be able to demonstrate that you:
- Specifically identified the unit being sold at the time of the transaction
- Have records showing the acquisition date, acquisition price, and the specific unit (lot) sold
- Maintained that documentation contemporaneously — not reconstructed after the fact
Side-by-Side Comparison
| Method | Best For | Documentation Required | Tax Impact |
|---|---|---|---|
| FIFO | Long-term holders; declining markets | Minimal — IRS default | Can be high in bull markets |
| HIFO | Active traders minimizing gains | Per-lot records required | Lowest short-term gains |
| Spec ID | Strategic tax planning | Per-transaction lot selection | Most flexible |
Can You Switch Methods?
Yes — but not retroactively, and not mid-year for the same wallet. Under Rev. Proc. 2024-28, you can change your cost basis method going forward, but you must do so before January 1, 2025 for the new per-wallet rules to apply cleanly. If you’re switching methods now, document the election clearly and ensure your crypto tax software supports the change.
One important note: you generally cannot use FIFO for one exchange and HIFO for another within the same tax year unless you’re using a consistent Spec ID approach. The IRS expects consistency.
What Your Crypto Tax Software Actually Does
Tools like Koinly, CoinTracker, CoinLedger, and ZenLedger all support multiple cost basis methods — but they don’t all implement them identically. Before relying on any software’s output, you need to verify:
- Which method is selected for each wallet/exchange
- Whether the software is applying per-wallet tracking (required post-2024)
- Whether DeFi transactions, staking rewards, and bridge transfers are handled correctly
- Whether lost or dormant wallet transactions are accounted for
We’ve reviewed thousands of crypto tax reports and the single most common error is the wrong cost basis method being applied silently — often defaulting back to FIFO after a software import or account merge.
The Bottom Line
Your cost basis method is one of the highest-leverage decisions in crypto tax planning. FIFO is the default, but it’s rarely optimal for active traders. HIFO and Spec ID can save thousands — if you have the records to support them.
If you’re not sure which method is applied to your portfolio, or if you’ve never reviewed your crypto tax software settings, that’s exactly what our $500 Crypto Tax Diagnostic is designed to catch.