how do you calculate a pigovian tax 
calculating a pigovian tax is notoriously difficult to get right in theory the amount of the tax should be exactly equal to the net cost of the externality it seeks to remedy thus the tax represents the difference between the social cost and the marginal private cost at a given level of production 3the bottom linewhile few consumers except for professional economists may recognize the name pigovian taxes are in wide use today there are however some doubts about their effectiveness 