I ran across this video a while ago on what can happen to you if you don't pay your taxes. At some point during your Bitcoin career, the cryptocoin will be converted to fiat and that's how they will catch you.
https://www.youtube.com/watch?v=hf2fNEUPjQwWell if you will just research about bitcoin, it is not register on the central bank of every country because government aer opposed on this so basically there are no taxes from bitcoin and the people who uses bitcoin doesn't pay tax anymore. And I think that is one of the reasons why government don't want bitcoin in there country.