Being the exclusive currency accepted for tax payment is an important part of what makes fiat currencies money.
The government is going to have to suck it up and accept taxes in cryptocurrency. In my country such laws have already been proposed.
I say have to as otherwise a rich private currency economy will grow unmolested by tax collectors.
Honestly I wouldn't mind that either. Governments in general are absurdly corrupt and taxes finance that corruption the same way drug users finance cartels.
Being the exclusive currency accepted for tax payment is an important part of what makes fiat currencies money.