---
title: "Crypto Cost-Basis Accounting Explained: FIFO, Specific Identification and Pooling"
description: "How matching sold cryptocurrency to original purchases alters capital gains liabilities under US IRS regulations compared to UK HMRC pooling requirements."
url: https://basisdesk.news/learn/crypto-cost-basis-fifo-lifo-hifo
published: 2026-10-28T06:30:31.309Z
modified: 2026-10-28T06:30:31.309Z
section: Regulation & Policy
author: Basis Desk Newsroom (AI-generated, source-verified)
sentiment: neutral
tickers: [BTC]
tags: [taxes, cost basis, IRS, HMRC, capital gains]
license: Quote with attribution to Basis Desk (basisdesk.news). Not financial advice.
---

# Crypto Cost-Basis Accounting Explained: FIFO, Specific Identification and Pooling

How matching sold cryptocurrency to original purchases alters capital gains liabilities under US IRS regulations compared to UK HMRC pooling requirements.

## Key points

- Cost basis is the original value of an asset used to calculate capital gains upon its sale.
- The US IRS defaults to First-In, First-Out (FIFO) but permits Specific Identification, allowing HIFO strategies.
- The UK HMRC mandates Section 104 pooling, calculating an average cost for all tokens of the same type.
- UK tax law utilizes a 30-day rule to prevent superficial loss harvesting.
- Transferring assets between personal wallets does not alter the underlying cost basis.

Calculating taxes on cryptocurrency sales requires determining the original purchase price of the asset, known as the cost basis. The accounting method a taxpayer uses to match sold tokens with previously purchased tokens dictates the taxable gain or loss reported to authorities. Rules diverge sharply between the US Internal Revenue Service and the UK HM Revenue & Customs, meaning identical trading histories yield distinct tax liabilities depending on the jurisdiction.

## The Core Concept of Cost Basis

When an investor sells cryptocurrency, tax authorities levy capital gains tax on the profit. This profit is calculated by subtracting the asset's original acquisition cost—including transaction fees—from the final sale price. If a taxpayer buys a single unit of $BTC, determining the cost basis is trivial. However, when an investor accumulates cryptocurrency over time through multiple transactions at different prices, selling a portion of that holdings requires a systematic method to identify exactly which units were sold.

The chosen accounting method determines the **cost basis**. This figure directly impacts the size of the capital gain or loss, influencing the immediate tax burden. Authorities in different countries prescribe specific frameworks for this calculation to prevent aggressive tax avoidance.

## The US Approach: FIFO and Specific Identification

In the US, the IRS treats cryptocurrency as property for tax purposes. By default, the IRS applies the **First-In, First-Out (FIFO)** method. Under FIFO, the first units of a cryptocurrency purchased are considered the first ones sold. Because cryptocurrency markets generally trended upward over the last decade, FIFO often results in the largest capital gains, as the earliest acquisitions typically have the lowest cost basis.

US taxpayers are not restricted to FIFO. The IRS permits **Specific Identification**, provided the taxpayer can adequately identify the exact units being sold. To use this method, the taxpayer must track the date and time each unit was acquired, the basis and fair market value at acquisition, the date and time of sale, and the fair market value at sale. 

With Specific Identification, taxpayers often utilize the Highest-In, First-Out (HIFO) strategy. HIFO matches the sale against the tokens acquired at the highest price. This maximizes the cost basis and minimizes the immediate capital gain, legally deferring taxes until the lower-cost units are sold.

## The UK Approach: Section 104 Pools

In the UK, HMRC treats cryptoassets similarly to shares, subjecting them to distinct capital gains tax rules that prohibit cherry-picking specific lots. Instead of tracking individual acquisition costs, UK taxpayers must use **Section 104 pooling**. 

Under this system, every time a taxpayer acquires tokens of a specific cryptocurrency, those units are grouped into a single "pool." The cost basis of the pool is the sum of all acquisition costs. When tokens are sold, the cost basis is calculated as an average of the entire pool. This smooths out price volatility and prevents taxpayers from selecting high-cost lots to artificially generate losses.

If a UK taxpayer buys Bitcoin across several years at wildly different prices, the cost basis for any partial sale is the average cost of all Bitcoin held in the pool at the time of the transaction.

## A Worked Example

Consider an investor who executes the following transactions:
1. Purchases 1 BTC for $10,000.
2. Later purchases another 1 BTC for $50,000.
3. Sells 1 BTC for $40,000.

Under the US default FIFO method, the investor is assumed to have sold the first BTC. The cost basis is $10,000, resulting in a taxable capital gain of $30,000.

Under the US Specific Identification (using HIFO), the investor selects the second BTC. The cost basis is $50,000, resulting in a deductible capital loss of $10,000.

Under the UK Section 104 pooling method, the two BTC merge into a pool with a total cost of $60,000. The average cost per BTC is $30,000. Selling 1 BTC yields a taxable capital gain of $10,000.

## The UK's 30-Day Bed and Breakfasting Rule

HMRC mandates strict anti-avoidance measures regarding the timing of trades. The "bed and breakfasting" rule dictates that if a taxpayer sells tokens and repurchases the same type of token within 30 days, the cost basis of the sold tokens is matched against the newly acquired tokens, rather than the Section 104 pool. 

Similarly, a "same day" rule requires that all acquisitions and disposals of the same token on the same day must be matched against each other first. These rules prevent UK investors from selling assets at a loss to harvest tax deductions and immediately repurchasing them to maintain their market position.

## Common Misconceptions

*   **Cost basis methods are universally interchangeable:** Taxpayers cannot switch methods arbitrarily to suit the current tax year. The US requires consistent application of a chosen method for a specific asset class unless the strict tracking requirements for Specific Identification are met.
*   **Moving tokens between personal wallets triggers a taxable event:** Transferring cryptocurrency between two wallets controlled by the same individual does not constitute a disposal. The cost basis remains intact, though tracking the original acquisition dates across wallets can complicate accounting.
*   **Tax software guarantees compliance:** While crypto tax calculators automate the application of FIFO or pooling, they rely entirely on the accuracy of imported exchange data. Missing transfers or decentralized finance transactions can irreparably break the cost-basis calculation.

## What to Watch

Tax authorities globally are increasing scrutiny on digital asset reporting. The US IRS continues to refine its guidance on specific identification protocols for digital assets held in custodial and non-custodial wallets. Meanwhile, jurisdictions adopting the OECD's Crypto-Asset Reporting Framework (CARF) will mandate systematic data sharing between exchanges and tax bodies. This automated data flow will leave less room for manual cost-basis adjustments, placing a premium on strict, real-time record keeping by investors.

*Disclaimer: Tax laws change constantly and specific applications vary by individual circumstance. This overview is not tax or legal advice.*

## FAQ

**What is Specific Identification?**

An accounting method permitted by the IRS where taxpayers identify the exact units of cryptocurrency sold by date, time, and purchase price to optimize capital gains.

**What is Section 104 pooling?**

A UK HMRC requirement where all units of a single cryptocurrency asset are pooled together, resulting in an average cost basis for taxation purposes.

**Can I use HIFO in the UK?**

No. HMRC rules strictly require matching same-day trades, 30-day repurchases, and then applying Section 104 pooling.

## Sources

1. [Frequently Asked Questions on Virtual Currency Transactions](https://www.irs.gov/individuals/international-taxpayers/frequently-asked-questions-on-virtual-currency-transactions) — Internal Revenue Service
2. [Cryptoassets Manual: Capital Gains Tax](https://www.gov.uk/hmrc-internal-manuals/cryptoassets-manual/crypto22100) — HM Revenue & Customs
3. [Cryptoassets Manual: Pooling](https://www.gov.uk/hmrc-internal-manuals/cryptoassets-manual/crypto22200) — HM Revenue & Customs

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