Pigouvian tax

Tax on activities generating negative externalities

A Pigouvian tax is a tax on any market activity that generates negative externalities. A Pigouvian tax is a method that tries to internalize negative externalities to achieve the Nash equilibrium and optimal Pareto efficiency. The tax is normally set by the government to correct an undesirable or inefficient market outcome and does so by being set equal to the external marginal cost of the negative externalities. In the presence of negative externalities, social cost includes private cost and external cost caused by negative externalities. This means the social cost of a market activity is not covered by the private cost of the activity. In such a case, the market outcome is not efficient and may lead to over-consumption of the product. Often-cited examples of negative externalities are environmental pollution and increased public healthcare costs associated with tobacco and sugary drink consumption.

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