The importance of distributional aspects of environmental policy has become even more evident over time. This paper deals with how to handle distributional aspects of public good provision optimally from a social welfare point of view, when distributional issues can also be handled through optimal non-linear income taxes. The analysis is based on a perturbation, or sufficient statistics, approach and we demonstrate that an optimally modified Samuelson rule, for the provision of public goods, can often be expressed in terms of a few estimable elasticities. In particular, we show the crucial role of the difference between the cross-sectional and individual income elasticity of the marginal willingness to pay for the public good.