Optimum Commodity Taxation in Pooling Equilibria.


This paper extends the standard model of optimum commodity taxation (Ramsey (1927)and Diamond-Mirrlees (1971)) to a competitive economy in which markets are inefficient due to asymmetric information. Insurance markets are prime examples: consumers impose varying costs on suppliers but firms cannot associate costs with individual customers and consequently all are charged equal prices. In such a competitive pooling equilibrium, the price of each good is equal to the average of individual marginal costs weighted by equilibrium quantities. We derive modified Ramsey Boiteux Conditions for optimum taxes in such an economy and show that, in addition to the standard formula, they [...]