No, bitcoin is not subjected to tax. The government will not be able to get any tax from bitcoin not unless they will be legalizing it which I don't think will be favorable to us users because that will be meaning that there will be other fees aside from the transaction fees that we already are paying.
Indeed, if they want to apply a tax on bitcoins, they must legalize it, however, in order to do so, they need to manage it well, and that is something that not every country can.