Under the CARF rules cryptocurrency service providers will have to provide details on all of their users, their transactions, and their held assets, reporting the data to HMRC, and if they are located outside to their relevant tax authority.

This means that tax authorities will be able share relevant data between jurisdictions depending on where the individual crypto investor is a resident for tax purposes. 

The tough regime will go live in 18 months with the first UK reporting required from 31 May 2027, and then international sharing of data between international tax authorities starting later in 2027.