Cost basis: what it means for crypto tax

Cost basis is what an asset cost you to acquire, including any fees. It is the number your capital gain or loss is measured against when you dispose of the asset, so an accurate basis is the foundation of a correct crypto tax report.

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

If you bought 1 ETH for 2,000 plus a 10 fee, your cost basis is 2,010. Sell it later for 3,000 and your gain is 990, not 1,000, because the fee raised your basis.

Why it matters for your tax

Cost basis is the single biggest driver of an accurate tax figure. Because every disposal leans on it, a wrong basis early in your history quietly distorts every later gain that draws on it.

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

• Cost basis guide
• Capital gain
• FIFO

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

Cost basis: what it means for crypto tax

Definition in context

Cost basis is the original value of an asset for tax purposes, usually the purchase price plus any fees or commissions. In crypto, it is the amount you paid to acquire a coin or token, including transaction fees. When you sell or dispose of the asset, your capital gain or loss is calculated as the difference between the sale proceeds and the cost basis.

Why it matters to crypto records

Accurate cost basis is crucial because it directly determines your taxable gain or loss. If you understate your basis, you may overpay tax; if you overstate it, you may underpay and face penalties. With many crypto transactions, tracking basis for each unit can be complex, especially when you acquire the same asset at different times and prices. Proper record-keeping of acquisition dates and amounts is essential.

Record example

You buy 0.5 BTC for $10,000 and pay a $50 fee, so your total cost is $10,050. Later, you sell that 0.5 BTC for $15,000. Your cost basis is $10,050, and your capital gain is $4,950. If you had bought another 0.5 BTC for $12,000, you would have two separate lots with different bases, and you would need to identify which lot you sold to calculate the gain correctly.

Distinctions and next steps

Cost basis is different from fair market value, which is the price at a given time. Basis is what you paid, while FMV is what it's worth. Also, basis can be adjusted for fees, and in some cases, for forks or airdrops. To manage basis, keep records of every acquisition, including fees, and choose a cost-basis method (like FIFO or specific identification) if allowed. Use a portfolio tracker or spreadsheet to track lots.

A cost-basis file should connect each acquisition to the source document that proves it. Retain the trade or payment record, quantity, price source, related fees and any later transfer that moved the asset without creating a new acquisition. If lots are combined in a spreadsheet, keep a link back to the individual transactions so the composition can be checked. When an input is missing, mark the assumption and the evidence sought rather than filling the gap with a convenient number. That discipline supports whichever permitted method is later applied to the records.

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.