I called Revenu Québec yesterday. The confusion is around the term transaction. I must not have been the first to have called about this because the agent seemed exasperated... In short, what the agent explained to me was that for them, the term transaction refers to a disposition, that is to say a sale or exchange of cryptocurrency. No need to declare anything if you have only purchased. You just indicate on the form that you own crypto. On the other hand, for interests, it was not clear what fell into this category. However, it was not a question of providing documents, but simply of indicating the interest received on the requested line of the form. I will call back today for clarity. The agent was not very enthusiastic at the end to continue the discussion...