By Yes. Coinbase has shared UK customer data with HMRC, and from January 2026 reporting to HMRC becomes a routine legal obligation for crypto exchanges under the Cryptoasset Reporting Framework (CARF). If you have used Coinbase and assumed HMRC would never know, it is time to update that assumption.
Here is what has actually happened, what changes from 2026, and what to do if you have gains you never declared.
What Coinbase has already shared with HMRC
This is not hypothetical. In October 2020, Coinbase wrote to affected UK customers to tell them HMRC had required it to hand over account information, following a legal notice from the tax authority. The requirement, as reported at the time, covered customers whose accounts had received more than £5,000 worth of cryptoassets during the 2019/20 tax year. HMRC confirmed the data collection, and Coinbase said fewer than 3 per cent of its UK customers were affected. Further customer notifications about HMRC data requests followed in 2021.
The details HMRC obtained through exercises like this allow it to match exchange activity against tax returns. That matching is what drives its nudge letter campaigns, which reached roughly 65,000 crypto investors in the 2024-25 wave. If one of those letters reaches you, read our guide on what to do about an HMRC crypto nudge letter.
From 2026: reporting becomes automatic under CARF
Until now, HMRC has relied on one-off information notices. From January 2026 the UK implements the OECD’s Cryptoasset Reporting Framework, which turns reporting into a standing obligation. Cryptoasset service providers, including Coinbase, must collect and report to HMRC:
- Who you are: name, date of birth, address, tax residency and your National Insurance number or Unique Taxpayer Reference
- What you did: the types of transactions you carried out and aggregate values across the year
The first reports, covering activity in 2026, are due by 31 May 2027, and international exchange of this data between participating countries follows from 2027. In short, the question stops being whether Coinbase reports to HMRC and becomes simply when.
It is not just Coinbase
Coinbase is the best-documented example because it notified customers publicly, but HMRC already receives data from major exchanges serving UK users, and CARF applies across the industry, including many overseas platforms through international data exchange. Decentralised wallets do not offer an escape either: public blockchains are traceable, and a single withdrawal from a KYC-verified exchange can link a private wallet to your identity. Our post on whether HMRC can track crypto explains the full picture.
What to do if you have not declared
First, work out whether you actually owe anything. Under HMRC’s Cryptoassets Manual, selling, swapping one coin for another, spending crypto and most gifts are disposals for Capital Gains Tax, and the annual exempt amount is now £3,000. Staking, mining and being paid in crypto can be subject to Income Tax instead.
If there is something to put right, act before HMRC writes to you. An unprompted disclosure through HMRC’s cryptoasset disclosure facility generally attracts lower penalties than one made after contact. We explain the process, and how we support you through it, on our HMRC crypto voluntary disclosure page.
Frequently asked questions
Has Coinbase already given my details to HMRC?
Possibly. In 2020 Coinbase notified UK customers whose accounts had received more than £5,000 in cryptoassets during the 2019/20 tax year that their details were being shared with HMRC, with further notifications in 2021. From January 2026, reporting becomes automatic under CARF.
Do other exchanges report to HMRC too?
Yes. HMRC already receives data from major exchanges serving UK customers, and from January 2026 the Cryptoasset Reporting Framework obliges cryptoasset service providers to report user and transaction data routinely.
Will HMRC know if I only made small trades?
Under CARF, reporting is not limited to large accounts, so assume your activity is visible. Whether tax is actually due depends on your gains, income and allowances, including the £3,000 Capital Gains Tax annual exempt amount.
I traded on Coinbase years ago and never declared anything. What should I do?
Check whether you had taxable gains or income in those years, and if so consider a voluntary disclosure through HMRC’s cryptoasset disclosure facility. Coming forward before HMRC writes to you generally means lower penalties.
Does moving crypto to a private wallet hide it from HMRC?
No. The withdrawal itself is recorded by the exchange, which links your wallet address to your verified identity, and public blockchains let analysts follow the funds from there.
Speak to us
Not sure what your Coinbase history means for your tax position? We work with a specialist crypto tax accountant UK clients rely on to review exchange records, calculate what is owed and, where needed, prepare a disclosure. Book a free, no-obligation consultation via our contact page.
This article is general guidance, not personal tax or financial advice. Tax treatment depends on your individual circumstances and rules can change. Crypto Asset Consultants does not provide FCA-regulated financial advice.