Capital Gains Tax on Crypto UK 2026 – 30-Day Rule, Bed & Breakfasting & Losses

The 30-day rule and Bed & Breakfasting are two powerful UK tax strategies most crypto traders don't know about. Learn how to use them to legitimately reduce your capital gains tax bill.

The 30-Day Rule (Wash Sale Prevention)

In the UK, if you sell an asset at a loss and buy the same asset within 30 days, you cannot claim the loss for tax purposes.

Example:

• Day 1: Sell 1 BTC at a £5,000 loss
• Day 10: Buy 1 BTC again
• HMRC will disallow the loss. The acquisition cost is adjusted forward.

How to work around it: Wait 31+ days before rebuying the same asset.

Bed & Breakfasting Strategy

"Bed & Breakfasting" is a legal tax strategy where you sell an asset at a loss, immediately buy a similar (but different) asset, and then swap back later.

Example with Crypto:

• You hold 1 BTC at a £5,000 loss
• Sell BTC today at a loss (claim the loss)
• Same day, buy 1 ETH (not the same asset, so 30-day rule doesn't apply)
• In 31+ days, swap ETH back to BTC

Result: You claimed a £5,000 loss, stayed in crypto, and can rebuy BTC. The swap back (31+ days later) is a new transaction, taxed at the time of swap.

Loss Offsetting & Capital Gains Allowance

Losses offset gains in the same tax year, but you can also carry forward unused losses indefinitely.

Example:

• 2025/26: Losses £8,000. Gains £2,000. Net: £6,000 loss (no tax). Carry forward £6,000 loss.
• 2026/27: Gains £10,000. Minus carried loss £6,000 = £4,000. Minus allowance £3,000 = £1,000 taxable × 20% = £200 tax.

Calculation Methods: FIFO vs Average Cost

HMRC allows you to use either method to match purchases with sales:

• FIFO (First-In-First-Out): You sell the oldest batch first (conservative)
• Average Cost: You use weighted average acquisition cost (often more tax-efficient)
• Specific Identification: You specify which batch you're selling (most tax-efficient, but requires meticulous records)

Pro Tax Planning Tips

• Timing: Realize gains and losses strategically within the tax year
• Use your allowance: £3,000 is tax-free – don't waste it
• Bed & Breakfast wisely: Use it to reduce tax without exiting crypto
• Track everything: Keep detailed records of all transactions, prices, and dates

Common Mistakes to Avoid

• Mistaking crypto-to-crypto swaps: They're taxable! BTC → ETH is a disposal, not a transfer.
• Forgetting staking income: It's income tax, not capital gains (higher rate!)
• Ignoring the 30-day rule: Costs you your loss claim
• Not claiming losses: Many people forget to offset losses and overpay

Strategies for 2026

Action: If you have losses, use Bed & Breakfasting before 31 December 2026 to lock them in. This is your last chance for the tax year.

Disclaimer: This article is for general informational purposes only and does not constitute tax advice. For individual tax advice, consult a licensed tax professional.