I cannot pay my tax in such place with bitcoin, when I don't earn in bitcoin. Assuming, I am paid in bitcoin, I don't see it as any problem to me. My bitcoin is very precious to me, so I will rather use it as an investment than giving it to the government.
If I have bitcoin and my government accepts bitcoin as a tax payment method, I will still not use my bitcoins to pay tax.
Because if I am not careful, I will break my privacy to tax governmental agency. With Bitcoin, I have my own bank and privacy if I have good practice. Use my bitcoins to pay tax, is one of bad practice, that I will not do.