my friend had some income in US and it was very very small so he forgot about it completely, until the letter from his country (non-US) tax authority arrived and they told him: "hey, you had this income in US. Why don't you tax it with us too?" and then he remembered. He paid the due tax, it was no big deal, the sum was very low. What I want to tell, is that it is not necessarily your country that must implement measures to tax bitcoin, but if you use the US-based exchange than you are in trouble too, your country may/will learn about it, because US has already implemented such measures (KYC and others) and the tax authorities collaborate very closely.