Crypto gas fees and transaction costs: UK tax guide
Quick answer: Some crypto acquisition and disposal costs may be deductible, but a gas fee is not automatically allowable just because it appears on-chain. Paying a fee in crypto is also a disposal of that fee token. Identify the purpose, value and tax treatment of each charge.
Understand allowable crypto transaction costs, gas fees paid in tokens, transfer charges and double-counting risks in UK tax calculations.
Which fees relate to buying or selling?
Separate a charge for acquiring or disposing of an asset from general portfolio, subscription or administrative expenses. The statutory allowable-cost rules govern CGT deductions. A tax-software subscription should not simply be deducted from capital gains without establishing a permitted basis. Keep invoices and exchange trade confirmations.
A crypto fee has two questions
Keep the expense and the token payment separate
A fee can require a deductibility assessment and a separate token-disposal calculation. Avoid deducting the same cost twice.
Read the diagram as text
- A. The expense. Is this cost allowable for the underlying transaction?
- B. The payment. Did paying in tokens dispose of an asset with its own cost?
Source: HMRC fees paid in tokens
Sources: HMRC: allowable costs
Gas paid in ETH creates a separate token disposal
If ETH worth £10 is used to pay a qualifying fee, record the disposal of that ETH as well as the underlying transaction. Its own matched acquisition cost may differ from £10. Do not subtract £10 twice from the principal trade because one export lists a net amount and another lists a separate fee.
Sources: HMRC: fees satisfied in tokens
Worked reconciliation: gross proceeds versus net receipts
Suppose a trade confirmation shows £2,000 gross proceeds and a £10 selling charge, while a bank receipt is £1,990. Start with either gross proceeds and one allowable deduction, or a clearly reconciled net amount. Applying the £10 deduction again to £1,990 understates the gain. Token-paid fees also require the separate disposal calculation described above.
Wallet transfers, failed transactions and approvals
Record the purpose of each fee: moving holdings, granting a token allowance, an unsuccessful trade or making a completed acquisition. These are not interchangeable. The chain confirms expenditure, but not necessarily an allowable deduction. Keep uncertain fees in a separate review category instead of applying a blanket software rule.
Fee review before filing
Check the trading pair, fee asset and whether a CSV amount includes the charge.
- Keep quantity and GBP value for fees paid in tokens.
- Match the fee to an acquisition, disposal or other activity.
- Check whether the import already reduced proceeds.
- Preserve a reason for any disallowed or manually adjusted fee.
Frequently asked questions
Are all Ethereum gas fees tax deductible? +
No. Their purpose and the applicable allowable-cost rules matter. Preserve evidence rather than treating every network charge as deductible.
Is paying a fee in crypto a disposal? +
Yes. HMRC treats the tokens used to satisfy a fee as disposed of at market value; their allowable cost is determined under the normal matching rules.