Cryptocurrency Explained — UK Tax, Risks and How It Works

Cryptocurrency has moved from a niche technology experiment to a mainstream asset class held by millions of UK adults. Yet many holders are unclear on what it actually is, how it works, and — critically — how HMRC expects them to account for it. This guide covers the essentials without the hype.

What is cryptocurrency?

Cryptocurrency is a form of digital currency secured by cryptography and operating on a blockchain — a distributed, publicly visible ledger that records every transaction. Unlike traditional currencies, most cryptocurrencies operate without a central authority such as a bank or government.

HMRC does not consider crypto to be currency or money. It is treated as property — a capital asset, like shares or land — for tax purposes.

How blockchain works

A blockchain is a chain of blocks, each containing a batch of verified transactions. New transactions are broadcast to a network of computers (nodes), validated by consensus, and added to the chain permanently. Once recorded, transactions cannot be altered without rewriting all subsequent blocks — making fraud extremely difficult.

Different blockchains use different consensus mechanisms:

• Proof of Work (PoW): Miners compete to solve complex puzzles to validate transactions and earn new coins. Used by Bitcoin. Energy-intensive.
• Proof of Stake (PoS): Validators are chosen based on the amount of cryptocurrency they stake as collateral. Used by Ethereum (since 2022). Much more energy-efficient.

Major cryptocurrencies

How HMRC taxes cryptocurrency

HMRC published detailed crypto tax guidance and treats different activities differently:

Capital Gains Tax on disposals

Every time you dispose of a cryptoasset, a CGT event occurs. A disposal includes:

• Selling crypto for pounds sterling
• Swapping one cryptocurrency for another (e.g. BTC → ETH)
• Spending crypto on goods or services
• Gifting crypto to someone other than a spouse

The gain is calculated as: Proceeds − Allowable Cost. The allowable cost is what you paid for the crypto (in GBP at the time of acquisition), including fees. After deducting the £3,000 annual exempt amount, gains are taxed at 18% (basic rate) or 24% (higher rate).

Crypto-to-crypto swaps

This catches many people out. Swapping Bitcoin for Ethereum is a disposal of Bitcoin at its GBP market value at the time of the swap — even though you never received sterling. You must calculate and report the GBP gain on every single swap.

Income from crypto

The following activities generate income tax (not CGT):

The crypto pooling rules

Because crypto can be purchased in multiple tranches at different prices, HMRC uses pooling rules similar to those for shares to calculate the cost basis:

1. Same-day rule: Crypto acquired on the same day as a disposal is matched first
2. 30-day rule (bed and breakfasting): Crypto acquired within 30 days after a disposal is matched next — preventing you from selling at a loss and immediately rebuying
3. Section 104 pool: All remaining holdings are pooled and averaged — each disposal uses an average cost per coin

Record keeping

HMRC requires you to keep records of every crypto transaction, including:

• Date of the transaction
• Type of transaction (buy, sell, swap, airdrop, etc.)
• Amount of crypto involved
• GBP value at the date of the transaction (use a reputable exchange rate source)
• Transaction fees (in GBP)
• Name of the exchange or wallet used

Records must be kept for at least 5 years after the 31 January Self Assessment deadline. Given the volume of transactions some active traders accumulate, dedicated crypto tax software (such as Koinly, CoinTracker or Recap) can automate much of this by connecting to exchange APIs.

Reporting requirements

You must file a Self Assessment tax return and report crypto if:

• Your total crypto gains in the tax year exceed £3,000
• Your total disposal proceeds exceed £50,000 (even if no tax is due)
• You received income from crypto (mining, staking, etc.)

The deadline is 31 January following the end of the tax year. Capital losses should also be reported — they can be carried forward to offset future gains.

Crypto losses

Losses on crypto disposals can be offset against gains from other assets (shares, property, etc.) in the same year, or carried forward indefinitely. If a coin becomes worthless — or access is permanently lost — you may be able to claim a negligible value claim from HMRC to crystallise the loss.

Key risks of cryptocurrency

• Volatility: Crypto prices can fall 50–90% in a bear market. Bitcoin has had multiple such drawdowns.
• Regulatory risk: Governments can and do restrict or regulate crypto. The UK FCA requires crypto marketing to include risk warnings.
• Security risk: Exchanges have been hacked. Self-custody (hardware wallets) reduces exchange risk but introduces the risk of losing your private keys permanently.
• Scams: Crypto is a common vector for investment fraud. If it sounds too good to be true, it is. The FCA maintains a warning list of unauthorised crypto firms.
• No FSCS protection: Crypto held on exchanges is not covered by the Financial Services Compensation Scheme.
• Tax complexity: The high volume of transactions and GBP conversion requirements create significant administrative burden.