Crypto tax glossary for United Kingdom
The words that show up when HMRC enters the conversation — in plain language, without the fog.
Taxable event
The moment something happens that HMRC can tax. Usually a disposal: selling for GBP, swapping one token for another, or spending crypto. Buying and holding normally isn't one.
Disposal
Getting rid of an asset — by selling, swapping or spending it. The word matters because a swap is a disposal too, even when no GBP moves.
Cost basis
What an asset cost you in GBP at the moment you acquired it, fees included. Your gain is what you received minus this number, which is why getting it wrong changes everything.
Capital gain / loss
The difference between what you got for an asset and its cost basis. Positive is a gain, negative is a loss. Whether and how each is taxed depends on United Kingdom's rules.
Matching method
The rule that decides WHICH of your past purchases you just sold, when you bought the same token many times at different prices. Countries impose different methods, and the choice changes the total.
Historical price
The value of an asset at the date and time of a past operation — not today's price. Every gain calculation needs it, and finding it by hand for each trade is what makes spreadsheets painful.
Crypto-to-crypto swap
Trading one token directly for another (ETH → USDT). In most systems this disposes of the first token and is measured in GBP at the moment of the trade, even though no bank account moved.
Stablecoin
A token designed to track a currency's value, like USDT or USDC. It feels like cash but is generally still an asset — moving into it is usually a disposal, not a safe harbour.
Self-custody wallet
A wallet whose keys only you hold — hardware or software. No statements arrive: the blockchain is the record, and reconstructing it later is your job.
Public address
The identifier others use to send you crypto. It's already public on the blockchain, so reading it needs no permission and exposes no control over your funds.
Private key / seed phrase
The secret that controls your funds. Nothing about calculating tax requires it. Any service asking for it is asking for the ability to move your money — no exceptions.
Read-only API key
An exchange credential that can look but not touch: it reads your history and cannot withdraw or trade. It's the only kind of key a tax tool should ever accept.
Transfer between your own wallets
Moving your own coins from A to B. Normally not a disposal — you still own the same asset. Counting it as a sale invents a gain that never happened.
Review desk
The step where you check each classified operation before anything is filed. The point of it: a number you can explain is a number you can defend to HMRC.