EXTERNALITIES AND PARTIAL TAX REFORM: DOES IT MAKE SENSE TO TAX ROAD FREIGHT (BUT NOT PASSENGER) TRANSPORT? *

Externalities such as pollution and road congestion are jointly produced by the use of intermediate inputs by firms and the consumption of final goods by households. To cope with such externalities, policy proposals often suggest partial tax reforms. This paper uses a simple general equilibrium model to explore the effects of a reform of taxes on freight transport in a second‐best setting. The theoretical model shows that the welfare effect of higher freight taxes is positive, unless passenger transport is severely under‐taxed and the tax reform attracts substantially more passenger transport. Moreover, the optimal freight tax may be below or above marginal external cost. Budgetary neutral tax reform exercises with a numerical simulation model for the U.K. suggest that, under a wide variety of parameter values, higher freight transport taxes are indeed welfare increasing. The welfare gain of freight tax reform rises with the level of the passenger tax, but the optimal freight tax declines at higher taxes on passenger transport. Substantial net benefits of tax reform are obtained only under labor tax recycling of the revenues.