If i sell my bitcoins to a site like coinbase at the end of the year do I need to declare that sale to the vat department and pay the 20% on what i received from coinbase ?
Don't do this. Don't sell bitcoins. And don't pay taxes. Just use bitcoins as a currency. Buy and sell with bitcoins. And fuck banks and goverments.
OP should keep a copy of this for his defense in court. "Your honor, I am not subject to the laws of my country. My online tax consultant tells me I don't have to pay taxes."