Pigouvian Taxes: Making Polluters Pay

How taxes on harmful activities can correct externalities, the idea's origins with Arthur Pigou, and practical examples from fuel to plastic.

When an activity harms others without the harm being paid for, economists call it a negative externality. Pigouvian taxes try to fix this.

The idea

In 1920, British economist Arthur Pigou argued that governments should tax activities that cause harm, setting the tax equal to the external cost. This makes the person causing the harm consider its full cost.

Why it works

A factory polluting a river doesn’t pay for the damage downstream.
A tax equal to the damage makes pollution costly, so the factory cuts pollution where cheapest.
The market then produces closer to the socially efficient amount.

Double benefit

Unlike most taxes, which distort behaviour, Pigouvian taxes improve outcomes by correcting behaviour, while also raising revenue. Some economists call this a “double dividend”.

Examples

Carbon taxes on fossil fuels.
Tobacco and alcohol taxes, partly for health costs.
Congestion charges on driving in busy areas.
Plastic bag charges.
Sugar taxes.

Challenges

Measuring the external cost precisely.
Political resistance: people dislike new taxes.
Regressivity: fuel taxes may hurt poorer households, which revenue can offset through transfers.

Pigouvian subsidies

For positive externalities, such as vaccines or research, governments can subsidise activities to encourage more of them.

The plastic bag charge

A city introduces a small charge for plastic bags at shops. Many shoppers start carrying cloth bags, and plastic bag use drops sharply, with less litter and blocked drains.

Thinking all taxes reduce economic efficiency

Pigouvian taxes can improve efficiency by correcting harmful externalities.

Key takeaways

Arthur Pigou (1920) proposed taxing harmful activities by their external cost.
Pigouvian taxes correct behaviour and raise revenue.
Examples include carbon, tobacco, congestion and plastic bag charges.
Measuring external costs and fairness are challenges.