In EU, the relating tax treatment of bitcoin for tax purposes differ depend on each EU country. However, purchasing and selling bitcoin does not incur VAT but bitcoin transactions may be subject to other taxes, such as income tax.
In no moment my question was about VAT. My question is related only to the profit you can make from converting Bitcoin to Euro, after you bought it for a cheaper price. Easy example: you buy 1 BTC for 1K EUR, you sell it six months later for 10K EUR. You made a profit of 9K EUR. I suppose you need to pay a tax for that 9K EUR profit.