I have been thinking of this for long and the reason being that a lot of bitcoin transaction is going online everyday in many countries and i think government can generate IGR from this if possible. I am not a programmer and i have a little knowledge about bitcoin technologies but i just want to know if it is possible.
It is possible to have tax in Bitcoin if you transact using centralized exchange that holds your identity and when you convert your Bitcoin to paper money, but I think it is impossible to put tax in all Bitcoin transactions especially if you use over the counter that is used to buy and sell massive amount of Bitcoin. There's nothing to worry about this if your country does't have a tax regulation about cryptocurrency gains but if IRS in your country declared it as an asset then you should pay your tax, and report to them every transaction you made.