Base from my recent post "Does bitcoin could be call a job?" I have read your opinions regarding to that. Doing these things is a form of earning money basically we have income. So does it need to be taxed? Because this is also a source of income, and we might call it as a job?
It depends on the country, but there are somewhere you will need to pay taxes when you sell your BTC. For instance, in Spain apparently, you will need to pay 16% once you make cash your BTC and put it in your bank account. 16% is the payment from 0 to 6.000 euros, 21% when you sell between 6.000 and 21.000, and so.
I don't know how Spanish government is going to manage the taxes, a mean, what kind of papers do you need to deliver to the institution, but I'm quite sure next year probably BTC is going to appear in some official taxes declarations documents.