Specific identification (Spec ID): what it means for crypto tax

Specific identification means choosing exactly which lots of an asset you dispose of, rather than following an automatic order like FIFO. Where allowed, it gives the most control over your gain, but it demands precise, contemporaneous records identifying each unit sold.

General information, not tax advice. Crypto tax rules differ by country and change over time, verify against your country's guidance or a qualified advisor.

An example

You might nominate your highest-cost lot for a sale to minimise the gain, provided you can document which units you sold.

Why it matters for your tax

Spec ID offers the most control, but the evidence burden is the catch: you must be able to show, per disposal, exactly which acquisition it came from.

CryptaTax handles this automatically across your wallets and exchanges, so the concept is applied consistently without you tracking it by hand. Try the crypto tax calculator →

Related terms

• HIFO
• Cost basis
• Lot

See the full crypto tax glossary for every term, or the crypto tax guides for how they fit together.

Understanding Specific identification (Spec ID): what it means for crypto tax in crypto records

Specific identification (Spec ID): what it means for crypto tax: records to review

Specific identification (Spec ID) is a method for determining the cost basis of assets you sell, and it applies directly to cryptocurrency holdings. When you own multiple units of the same crypto asset—say, 1 BTC bought at different times and prices—you can choose which specific units you are selling at the moment of disposal. This is in contrast to default methods like FIFO (first-in, first-out) or average cost, which assume a fixed order or blend. The core idea is that you, the taxpayer, have the ability to pinpoint the exact acquisition date and cost of the units you are disposing of, thereby controlling the resulting capital gain or loss. This method is powerful because it lets you optimize your tax outcome, for example, by selling higher-basis lots to reduce gains in a profitable year, or selling lower-basis lots to realize a loss for offsetting other gains.

Specific identification (Spec ID): what it means for crypto tax: a record-based example

To use Spec ID effectively, you must maintain meticulous records. For each purchase, you need a unique identifier—such as a transaction hash, wallet address, or a custom lot number—along with the date, quantity, and cost in your local currency. When you sell, you must specify which lot you are selling at the time of the sale, not later. This contemporaneous designation is crucial; you cannot retroactively assign a sale to a lot after the fact. In practice, this means your crypto exchange or wallet software must support lot-level tracking, or you must keep a separate spreadsheet or ledger that links each disposal to a specific acquisition. Without such records, you risk being forced into a default method, which may not be favorable.

Specific identification (Spec ID): what it means for crypto tax: related concepts

A self-contained example: Suppose you bought 0.5 BTC on January 1, 2023, for $10,000 (cost basis $20,000 per BTC), and another 0.5 BTC on March 1, 2023, for $15,000 (cost basis $30,000 per BTC). Later, on June 1, 2023, you sell 0.3 BTC for $25,000 per BTC. Under Spec ID, you could choose to sell the 0.3 BTC from the January lot, giving you a gain of ($25,000 - $20,000) * 0.3 = $1,500. Alternatively, you could choose the March lot, giving a loss of ($25,000 - $30,000) * 0.3 = -$1,500. The choice is yours, but you must document that you sold the January lot or the March lot at the time of sale. If you fail to specify, the default might be FIFO, which would use the January lot first, resulting in the $1,500 gain.

Specific identification (Spec ID): what it means for crypto tax: practical next step

Distinctions: Spec ID differs from FIFO, which always sells the oldest lots first, and from average cost, which blends all costs into a single per-unit basis. It also differs from HIFO (highest-in, first-out), which sells the highest-cost lots first to minimize gains, but HIFO is not universally allowed. Spec ID is the most flexible but also the most record-intensive. It is not available in all jurisdictions; some tax authorities require a specific method or do not permit lot-level selection for crypto. Always check your local rules. Practical next steps: If you want to use Spec ID, start by auditing your current holdings and assigning lot numbers to each acquisition. Use a crypto tax software that supports lot-level tracking, or maintain a detailed spreadsheet. Before each sale, decide which lot to sell and record that decision immediately. Finally, consult with a tax professional who understands crypto to ensure your method is compliant with your jurisdiction's regulations.

A careful next step

Before acting on this term, return to the original record and write down the question it raises: what changed, which source proves it, and whether another related concept describes the event more accurately. Keep that note with the export or wallet evidence. It makes a later review faster and avoids turning a short label into an unsupported conclusion about tax, accounting or reporting.