According to
The National Post, Canada's tax agency is asking the court to oblige the country's leading cryptocurrency exchange Coinsquare to transfer the data of all its users since 2013.
The CRA sent a corresponding appeal – the first in the history of Canada-in September. In it, the Agency States that this information is necessary in order to make sure that Coinsquare customers "comply with their obligations" under the country's tax laws.
In other words, the CRA wants to check whether all customers have paid taxes and whether cryptocurrencies have been used to hide assets. It is assumed that this will be done on the basis of tax returns for previous years.
Tax lawyer David Piccolo explained that if discrepancies are found in relation to the trader, a larger audit may be initiated. He noted the importance of the CRA's appeal to the court, since this is the first active action on the part of the Agency aimed at obtaining such a large amount of information about the clients of the cryptocurrency exchange.
source:
https://nationalpost.com/news/politics/cra-goes-after-client-details-of-major-canadian-cryptocurrency-marketplace-in-battle-against-underground-economy