The IRS knows about the cryptocoins and wants you to pay taxes on them. The Wall Street Journal reports that the warning letters are going out.
An IRS spokesman declined to say whether the letters stem from information turned over by digital-currency platform Coinbase. In mid-March of 2018, Coinbase provided data—under a federal court order—on about 13,000 accounts requested by the IRS. … The Coinbase customers whose information was turned over bought, sold, sent or received digital currency worth $20,000 or more between 2013 and 2015. For federal tax purposes, cryptocurrencies such as as bitcoin are treated as investment property akin to stock shares or real estate.
You may not be interested in paying taxes, but the government is interested in the companies that helped you not pay taxes and it turns out those companies are happy to help the government help you pay your taxes. QED!