In order to answer that we need to be clear what Marx said. Your earlier statement that "Marx envisaged that in the higher phase of communism, the state would 'wither away,'" is false, though it is popular with people of a Leninist disposition. For Marx, communism was communism. He never said that its lower phase involved a state.
A subtler distinction: Marx tended to have a bureaucratic conception of the state, whereas Engels argued for the class nature of the state. Thus it is incorrect to say that Marx was interested merely in the "coercive aspect of the state". Engels was interested in that aspect of the state, but Marx had a more thoroughgoing rejection of the state as "inhuman". But the end result is the same: for Marx and Engels the state is transcended in post-capitalist society.
So, no: there will be no taxes, value or state in post-capitalist society. But there will be common ownership of the means of production, their democratic control, with production solely for use.
-- Lew