It purely depends upon the country which you live. Because as far as i know there is no tax for bitcoin. If the government announced to pay tax means then you have to pay only. Paying tax is good for economic growth of the country. Once it is legalized by government then automatically tax will be compulsory. At the same time U.S. government collect tax from the people for bitcoin.
How difficult it is to understand that Bitcoin doesn't need to be legalized or categorized in order for people to pay tax over their crypto holdings and profits? It's a common misconception that will end up making people run into legal problems with how they use their exchange for trading and storage purposes. It won't take long before governments will make sure that every centralized exchange shares user data on a daily or weekly basis with them. It's a threat not many people think about, but it's going to happen, and maybe it has already happened but we don't know it yet....