📝 Description
Learn how cryptocurrency gains are calculated in the United Kingdom following HMRC rules.
⚠️ Warnings
Capital Gains Tax rules apply to all crypto asset disposals.
Specific matching rules must be applied in a strict, sequential order.
⚖ HMRC Share Pooling Rules
The UK uses a specific calculation method called HMRC share pooling rules. This method determines how the cost basis of crypto assets is calculated when they are sold.
The system follows three rules in a strict order:
Same-Day Rule
30-Day Rule (Bed and Breakfast Rule)
Section 104 Pool
Rule 1: Same-Day Rule
If you buy and sell the same asset on the same day, the transactions are matched together.
Example:
Date | Action |
10 March | Buy 1 ETH for £2,000 |
10 March | Sell 1 ETH for £2,300 |
Gain: £300
Older holdings are not used for the calculation.
Rule 2: 30-Day Rule (Bed and Breakfast Rule)
If you sell crypto and repurchase the same asset within 30 days, the new purchase is matched with the earlier sale.
Example:
Date | Action |
1 June | Sell 1 ETH for £2,000 |
10 June | Buy 1 ETH for £1,800 |
Gain: £200
This rule prevents investors from selling assets to realise a loss and immediately repurchasing them.
Rule 3: Section 104 Pool
All remaining transactions are placed into a pool for each asset. The pool uses an average cost basis.
Example pool:
Asset | Quantity | Total Cost |
BTC | 3 | £90,000 |
Average cost: £30,000 per BTC
If you sell 1 BTC for £35,000: Gain: £5,000
💡 Good to know
Pooling is done per asset, not per wallet.
All holdings of the same crypto are combined across:
Exchanges
Wallets
Platforms