Many traders wrongly assume they don’t need to report crypto activity or fail to include all wallets and exchanges.
British crypto traders could face unexpected tax bills if they fail to properly report their gains, experts have warned, after HM Revenue & Customs (HMRC) reminded traders that profits above £3,000 may be taxable.
HMRC Issues Crypto Tax Warning
In a post on X last week, HMRC issued a warning to traders about keeping track of their taxable crypto gains.
“If your crypto profits have taken off, you may need to pay tax,” it wrote.
“Crypto gains above £3,000 count towards your taxable allowance. Check if you need to pay tax on cryptoasset profits and make sure your tax status isn’t lost in space.”
The U.K. tax authority has increasingly scrutinised digital asset activity as crypto adoption grows, with exchanges required to share transaction data.
New Crypto Tax Reporting Rules
The move comes after new crypto tax reporting rules began to be enforced from Jan. 1, 2026.
Part of the new rules included U.K.-based exchanges and wallet providers being required to collect detailed transaction and customer data for all U.K. users.
The measures form part of the U.K.’s adoption of the Organisation for Economic Co-operation and Development’s Crypto-Asset Reporting Framework (CARF).
Under the framework, crypto-asset service providers now report information including user identities, transaction values and wallet movements directly to HMRC.
The change marks a shift away from a system largely dependent on self-assessment and voluntary disclosure.
Once reporting begins, HMRC will be able to cross-check tax returns against exchange data.
The first report for 2026 calendar tear must be submitted to HM Revenue & Customs (HMRC) by May 31, 2027.
The ‘Biggest Mistake’ Crypto Traders Make With Tax
Andrew Duca, founder of crypto tax platform Awaken Tax, said the most common mistake among British investors is assuming they do not need to file crypto taxes in the first place.
“The biggest mistake by far is thinking that you don’t need to file crypto taxes at all, or that staying under certain thresholds exempts you from reporting,” Duca told CCN.
He added that many investors rely on software that cannot process complex transactions such as decentralised finance (DeFi) activity, yield farming or liquidity pool participation, leading to overpayment or inaccurate filings.
“Failing to add all wallets and exchanges to your records is also common, as well as not understanding that crypto swaps are taxable events,” he said.
HMRC considers disposals to include selling crypto for pounds, exchanging one token for another, or using crypto to pay for goods and services.
Duca stressed that tax liability does not arise only when converting crypto into sterling.
“It’s super important to understand which events are taxable and which aren’t,” he said.
According to Duca, buying Bitcoin with pounds or transferring crypto between personal wallets are not taxable events.
However, swapping Bitcoin into pounds and earning income from on-chain activities such as staking rewards, airdrops, liquidity pools or yield farming may trigger tax obligations.
HMRC obtains transaction information directly from exchanges, Duca said, noting that platforms serving U.K. customers are legally required to share user data with tax authorities.
“These usually happen automatically,” he added.
Calculating Gains
Calculating gains can be particularly complex for frequent traders operating across multiple exchanges.
HMRC applies a three-tier “share pooling” system to determine cost basis.
Under the so-called same-day rule, assets bought and sold on the same day are matched first.
If no same-day match applies, the tax authority looks at purchases made within the following 30 days.
Any remaining disposals are matched against the average cost of the pooled holdings.
“It is extremely complex, which is why using crypto tax software becomes invaluable, as it’s designed to automatically support this pooling algorithm, and calculate everything accurately,” Duca said.
For investors who receive a so-called “nudge letter” from HMRC — a warning that the authority believes tax may be owed — Duca advised seeking professional help immediately.
“If you’ve received a warning letter from HMRC, the best thing to do is contact a crypto specialised accountant as soon as possible to get some professional and legal advice in order to respond properly,” he said.
He also recommended generating comprehensive transaction reports and being prepared to settle any outstanding liabilities.
“If you owe taxes, you’ll need to settle them,” he said.
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