it depend on the area and the country where you are living, if your country has imposed tax on bitcoin they you have to pay tax but i thin still not a single country has yet consider bitcoin as legal currency therefore there is still no tax on bitcoin.
That is absolutely incorrect. Bitcoin doesn't have to be a currency for taxes to be imposed on it.
Taxes are imposed on income / profits and you definitely can profit using bitcoins.
but i think it is up to your country policy, if your country consider bitcoin as legal and then impost tax on it then you must have to pay tax on it ans you will have no other choice.