Bitcoin cost basis is the amount a company paid to acquire each unit it holds, and it determines the gain or loss recorded when those units are sold. Companies typically use specific identification, first-in first-out (FIFO) or weighted average cost. The right choice depends on the accounting framework, the tax rules in each jurisdiction and the company's systems.
This article explains how each method works, where they lead to different results, and what records a finance team needs.
Why Bitcoin cost basis matters
A company that buys Bitcoin over time will hold units acquired at different prices. When it sells part of the holding, it must decide which units have been sold. That decision sets the cost figure that is compared against the sale proceeds.
Cost basis affects:
- Reported gains and losses on disposal.
- Tax payable, where tax is charged on realised gains.
- Disclosures, including those required under the FASB standard on digital assets (ASU 2023-08).
- Audit work, since auditors will test that the method is applied consistently.
Under ASU 2023-08, holdings are measured at fair value, so cost basis no longer drives the balance sheet value. But it still matters. The standard requires disclosure of the cost basis of significant holdings, the difference between proceeds and cost on dispositions, and the method used to determine cost. See ASU 2023-08: fair value accounting for Bitcoin explained.
Under IFRS, cost basis matters even more where the cost model is used, because it is the carrying amount before impairment. See how Bitcoin is accounted for under IFRS.
The main methods
Specific identification
Each unit sold is matched to a specific acquisition lot. The cost of that lot is used to calculate the gain or loss.
- Strengths: precise, and allows deliberate choices about which lots to sell.
- Weaknesses: requires the company to be able to identify and track each lot through custody. Choosing lots for a favourable result can draw scrutiny, so the selection must be documented at the time of sale.
First-in, first-out (FIFO)
The earliest units acquired are treated as the first sold.
- Strengths: simple, objective and widely understood.
- Weaknesses: in a rising market, older lots usually have lower cost, so FIFO tends to produce larger reported gains on sale.
Weighted average cost
The total cost of all units held is divided by the number of units. Each sale uses that average.
- Strengths: smooths results and is easy to apply to frequent, small purchases.
- Weaknesses: the average must be recalculated after each acquisition, and it removes the ability to match sales to specific lots.
Other methods exist in some jurisdictions, and some tax regimes prescribe a particular pooling approach. Companies should check what is permitted locally.
A simple worked example
Assume a company makes three purchases and then sells 1 BTC. The prices are illustrative only.
| Lot | Units | Price per BTC | Total cost |
|---|---|---|---|
| Lot A | 1 | 30,000 | 30,000 |
| Lot B | 1 | 50,000 | 50,000 |
| Lot C | 1 | 40,000 | 40,000 |
The company sells 1 BTC for 60,000.
- FIFO: cost is Lot A, 30,000. Gain is 30,000.
- Specific identification (Lot B): cost is 50,000. Gain is 10,000.
- Weighted average: cost is 120,000 / 3 = 40,000. Gain is 20,000.
Same sale, same cash. Three different reported gains. This is why the method must be chosen deliberately, documented in policy and applied consistently.
Accounting method vs tax method
The method used for financial reporting does not have to match the method used for tax. In many cases it cannot, because tax law sets its own rules.
This creates two parallel records:
- An accounting ledger, following the policy agreed with auditors.
- A tax ledger, following the rules of each relevant jurisdiction.
Where they differ, the gap feeds into deferred tax calculations. The principles are covered in how Bitcoin is taxed for companies. Companies should take their own accounting and tax advice in each jurisdiction where they operate.
CFO tip: decide your cost basis method before the first purchase, write it into your Bitcoin treasury policy, and make sure your custody and accounting systems can support it. Changing method later is possible but adds work and invites questions.
What records are needed
Every method depends on good data. For each acquisition, a finance team should record:
- Date and time of the trade.
- Number of units acquired.
- Price per unit and total consideration.
- Fees and commissions, and how they are treated.
- Counterparty and trade confirmation reference.
- Custody account or wallet where the units are held.
For each disposal, record the same details plus the lots matched and the gain or loss calculated.
These records should be reconciled regularly to custodian statements and to the general ledger. Transfers between the company's own custody accounts should be tracked so that lot history is not lost.
Choosing a method
Questions to ask before deciding:
- What does our accounting framework require or permit?
- What do the tax rules require in each jurisdiction where we operate?
- How often will we buy and sell?
- Can our custodian and accounting systems track lots individually?
- What will our auditors expect to see?
For most corporate treasuries that buy in tranches and rarely sell, the method chosen will have limited effect year to year. It matters most when the company starts to sell, rebalance or use Bitcoin for payments. See our audit readiness checklist for the controls that support each method.
How The Bitcoin World helps
We help finance teams set up execution and record-keeping so every lot is captured cleanly from the first trade, with confirmations that reconcile to custody statements. Execution and custody are carried out by licensed third-party institutions. See our OTC liquidity and corporate treasury services, or the glossary for terms.