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M09.L03 — Taxes: Incidence, Deadweight Loss, and the Role of Elasticity

Module: Module 09 — Price Regulation, Taxes, and Subsidies Lesson: L03 of 05 Duration: ~30 minutes Level: Introductory Provenance: Khan Academy Microeconomics | OpenStax Principles of Microeconomics 3e

Learning Objective

Explain how taxes affect market outcomes and why elasticity determines who bears the burden.

Tax Incidence in Australia

A per-unit tax (e.g., fuel excise at ~49c/L) shifts the supply curve upward by the tax amount. Consumers pay a higher price, producers receive a lower net price, and the tax burden falls more heavily on the side with inelastic demand or supply. Deadweight loss occurs because the tax reduces mutually beneficial trade.

Worked Example

Fuel Excise Tax

  1. Pre-tax equilibrium: Price = $1.50/L, Quantity = 10M liters.
  2. Tax imposed: $0.49/L.
  3. New equilibrium: Consumer price = $1.80/L, Producer price = $1.31/L, Quantity = 8M liters.
  4. Incidence: Consumers pay $0.30 more, producers receive $0.19 less. Deadweight loss = loss of 2M liters traded.

Common Misconception

"Consumers always bear the full burden of taxes."

Tax incidence depends on elasticity: if demand is elastic, producers bear more of the burden; if supply is elastic, consumers do.

Key Takeaways

  • Taxes create a wedge between consumer and producer prices.
  • The more inelastic side bears more of the tax burden.
  • Deadweight loss represents lost gains from trade.
  • Australian examples include GST (broad-based) and tobacco taxes (targeted).

Practice

  1. How does a tax affect the equilibrium price and quantity?
  2. Why does deadweight loss occur with taxes?
  3. How does elasticity determine tax incidence?

Further Resources

Provenance: Khan Academy Microeconomics | OpenStax Principles of Microeconomics 3e