3. Corrective Tax (Pigouvian Tax)

Based on Dr. Said's Figure 6 + Carbon Tax Application (slides pp. 58-63)

How It Works

Government imposes a tax on producers equal to the MEC per unit. This internalizes the external cost into producers' decisions.

Corrective Tax = MEC per unit (also called Pigouvian Tax, named after economist Arthur Pigou)

Why does the tax work? Before the tax, producers only see MPC. After the tax, their effective cost becomes MPC + Tax = MPC + MEC = MSC. Now they're making decisions based on the TRUE social cost. The supply curve shifts up from S1 (MPC) to S2 (MPC + Tax = MSC), and the new equilibrium naturally occurs at the efficient point!

Interactive Chart

Tax Revenue Price Labels
$10

Step-by-Step Explanation

Results of Corrective Tax (Figure 6)
  • Equilibrium changes: E1 to E2. Quantity decreases from q1 to q2. Price increases from P1 to P2.
  • Consumers: Consume less (q2), pay more (P2). Consumer surplus decreases.
  • Producers: Produce less (q2), receive less (P3 = P2 - Tax). Producer surplus decreases.
  • 3rd parties: Less pollution damage. Gain from reduced externality.
  • Government: Collects tax revenue = Tax * q2. Can compensate affected parties or fund public services.
  • Net effect: Efficiency gains (the former DWL triangle becomes gains).
Does the Tax Eliminate Pollution?

No! The corrective tax does NOT reduce pollution to zero. As Dr. Said's slides explain:

"The corrective tax does not reduce the pollutants in the streams to zero. It merely rises the cost of using the stream to reflect the marginal damage done to alternative users."

After the tax, producers compare the tax cost with alternatives: recycling waste, purifying waste before disposal, or reducing output. They choose whichever maximizes profit.

Tax Revenue Uses

The tax revenue can be used for:

  • Compensating those harmed by remaining pollution (fishers, recreational users)
  • Improving government services
  • Reducing other taxes
  • Example: Washington State carbon revenue (2017): Transportation $400M, Education $380M, Low-Income $124M

Carbon Tax Application

Global warming from CO2 emissions is a classic negative externality. A corrective tax on carbon emissions can reduce the greenhouse effect. (Dr. Said's slides pp. 58-63)

Investopedia: Pigouvian Tax World Bank: Carbon Pricing Dashboard