The issue of cryptocurrency and tax has recently become popular. States may want to derive a tax income from this situation. But this is not a simple matter. How will they get the tax as bitcoin? This is a very complicated issue. I don't think it's possible for now.
I don't think we should even think about it but there are countries that already taxed Bitcoin.
This depends though on how they are using Bitcoin. If they are using Bitcoin in a company and they are accepting it as a payment or salary, they would be under the law of income tax and that would obviously be taxed.