The UK may be following the IRS playbook on cryptocurrency as HRMC has requested exchanges to provide customer data for the period from April 2017 to April 2019. If you recall, back in 2016 the IRS sued Coinbase for customer data and, just recently, announced plans to send 40,000 “educational” letters to cryptocurrency traders, making clear that any trading gains should have resulted in proper tax filings. HRMC may follow suit.
“Under HMRC rules, taxpayers who fail to disclose their gain could face a 20% capital gains tax plus any interest and penalties of up to 200% of any tax due. Those found to have evaded the tax could also face criminal charges and jail terms.” 1
1Bloomberg Tax, August 14, 2019 You Didn’t Pay U.K. Tax on Big Crypto Gains-Own Up to It