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Glossary

Blockchain
A shared digital record of transactions copied across many computers.
Wallet
An app or device that stores the keys to your crypto.
Exchange
A platform where you buy and sell crypto for pounds or other tokens.
Seed phrase
Recovery words that restore wallet access — never share them.
NFT
A unique digital token representing ownership of a specific item.
Stablecoin
A token designed to hold a steady value against fiat currency.
CARF
Cryptoasset Reporting Framework — exchange reporting to HMRC.
FCA register
Official list of authorised and registered financial firms.
Disposal
Selling, swapping, spending or gifting crypto — may trigger CGT.
Pooling
HMRC method of averaging acquisition cost per token type.
DeFi
Decentralised finance — lending, swapping and earning via software instead of banks.
SA108
HMRC capital gains supplementary form — includes dedicated cryptoasset boxes from 2024/25.
KYC
Know Your Customer — identity checks required before trading on UK crypto platforms.
MLR registration
FCA registration under Money Laundering Regulations — not full investment authorisation until 2027.
FSCS
Financial Services Compensation Scheme — protects bank deposits, not crypto on exchanges.
Hardware wallet
Physical device storing crypto keys offline.
Capital Gains Tax
Tax on profit when you dispose of assets including crypto.
UTR
Unique Taxpayer Reference — 10-digit number for Self Assessment.
DEX
Decentralised exchange — token swaps via smart contracts, not a central company.
Nudge letter
HMRC letter suggesting undeclared tax based on third-party data.
Voluntary disclosure
Reporting previously undeclared tax to HMRC before an investigation.
Section 104 pool
HMRC average cost pool for each token type when calculating CGT.
30-day rule
HMRC matching rule — rebuys within 30 days of selling match the sale first.
Consumer Duty
FCA requirement to deliver good outcomes for retail customers — applies to crypto from 2027.
Pig butchering
Long-con romance scam leading to fake crypto investment platforms.