CryptoTax UK · Guide
MetaMask Tax UK — HMRC Guide for 2025/26
MetaMask is the most popular Ethereum wallet and gateway to DeFi. Every swap, liquidity provision and NFT purchase made via MetaMask may have UK tax consequences. This guide explains what is taxable and how to get your transaction history. Educational only — not tax advice.
Calculate my MetaMask tax →Which MetaMask transactions are taxable?
Any disposal of a crypto asset creates a CGT event. Through MetaMask this includes: swapping tokens on Uniswap or other DEXs, selling NFTs, removing liquidity from a pool, and bridging assets across chains. Simply holding, or transferring between your own wallets, is generally not taxable.
How to export your MetaMask history
MetaMask does not provide a built-in export. Go to Etherscan.io, search your MetaMask wallet address and use the 'Download CSV Export' function. For other chains (Polygon, Arbitrum, BSC) use the equivalent block explorer. Repeat for each wallet address you use.
Gas fees and allowable costs
Ethereum gas fees paid on disposal transactions can typically be added to the allowable cost, reducing your gain. Gas fees on acquisition transactions add to your cost basis. Keep a record of gas fees paid on each transaction.
DeFi complexity
DeFi activity through MetaMask is an area where HMRC guidance is still developing. If you have significant DeFi activity, specialist crypto tax advice is strongly recommended before filing.
Frequently asked questions
Are MetaMask swaps taxable in the UK?
Yes — swapping ETH for USDC, or any token-to-token swap, is a disposal of the first asset for CGT purposes. The disposal proceeds are the GBP value of the asset received at the time of the swap.
How does HMRC know about MetaMask transactions?
All MetaMask transactions are recorded permanently on public blockchains. HMRC has invested significantly in blockchain analytics capabilities and can trace wallet addresses linked to individuals.
Can CryptoTax UK process MetaMask Etherscan exports?
Yes — download your Etherscan CSV and upload via Import CSV (Premium). CryptoTax UK will apply HMRC's matching rules and calculate your gain per disposal.
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Calculate my MetaMask tax →Educational guidance only. CryptoTax UK is not a regulated tax adviser and the information above does not constitute tax, legal or financial advice. Always confirm your specific position with HMRC or a qualified accountant before filing.