Norbert Ladoux

Externalities and optimal taxation

This paper re-examines the optimal tax design problem (income and commodities) in the presence of externalities. The nature of the second-best, and the choice of the tax instruments, are motivated by the informational structure in the economy. The main results are: (i) environmental levies (linear or nonlinear) differ in formula from Pigouvian taxes by the expressions for the optimal tax on private goods; (ii) externalities do not affect commodity tax formulas (linear and nonlinear) for private goods; (iii) externalities do not affect the income tax structure if commodity taxes are nonlinear and affect it if commodity taxes are linear; and (iv) a general income tax plus strictly Pigouvian taxes are sufficient for efficient taxation if individuals of different types have identical marginal rates of substitution (at any given consumption bundle).

Environmental Taxes with Heterogeneous Consumers: An Application to Energy Consumption in France

Abstract This paper constructs a model with four groups of households who have preferences over labor supply, consumption of polluting (energy related) and non-polluting (non-energy) goods, and emissions. It quantifies the model for the French economy and computes its optimal tax equilibria under nine second-best tax regimes. We find that the redistributive role of environmental taxes requires the polluting goods to be taxed at a rate much below their marginal social damage. These goods may even require an outright subsidy if the society values equality ‘a lot’. Secondly, if environmental taxes that have an exclusively externality-correcting role, they benefit all types—although the gains are rather modest. The gains and losses become more substantial when environmental taxes have a redistributive role as well. Third, setting the environmental tax at its Pigouvian level, rather than its optimal externality-correcting-cum-redistributive level, benefits the high-income group at the expense of the low-income groups. Fourth, nonlinear taxation of polluting goods, and nonlinear commodity taxation in general, is a powerful redistributive mechanism. Fifth, introducing environmental taxes in the current French tax system, with its suboptimal income taxes, results in substantial welfare gains for the highest income group and a sizable loss for the least well-off persons.

Second-Best Pollution Taxes and the Structure of Preferences

We characterize optimal taxes on polluting and nonpolluting goods in Ramsey and Mirrlees second-best environments. The polluting good tax differs from the Pigouvian tax by Ramsey terms in the first and by Stiglitz/Mirrlees plus another adjustment term in the second. These terms can be positive, negative, or zero. If preferences are weakly separable in public and private goods, with the private good subutility weakly separable in labor and produced goods, nonpolluting goods are taxed uniformly and the concept of a tax differential between polluting and nonpolluting goods is well defined. The differential is then less than the Pigouvian tax in the Ramsey framework, but it can be greater, equal to, or smaller than the Pigouvian tax in the Mirrlees second best. In Mirrlees second best, if preferences are separable in labor supply and other goods, the second-best tax differential is identical to the Pigouvian tax.

Energy Taxes and Oil Price Shocks

Abstract This paper examines if an energy price shock should be compensated by a reduction in energy taxes to mitigate its impact on consumer prices. It shows that the consumer price should not increase by as much as the producer price, implying a small reduction in the energy tax in dollars. The energy tax rate, on the other hand, decreases sharply. This decline is primarily due to an adjustment in the Pigouvian component: A constant marginal social damage being divided by a higher producer price. The redistributive component of the tax remains at about 10% of the social cost of energy.

Income tax reform in France: a case study

This paper calibrates the graduated income tax system currently in place in France while assuming that the number of earning-ability types in the economy is four. It also computes the optimal linear and nonlinear income tax schedules for this economy. Its main finding is that while an optimal linear income tax is (in most scenarios) welfare-superior to the current tax system, the welfare gain may be small. On the other hand, an optimal general income tax leads to substantial welfare gains over the present system.