8.1 surplus with a tax

The video begins by reviewing consumer surplus (the area below the demand curve and above the price) and producer surplus (the area below the price and above the supply curve). Total surplus is the sum of these two.

A tax creates a wedge between the price buyers pay and sellers receive, reducing the quantity. This tax wedge is represented graphically, and the resulting tax revenue is shown as a rectangle.

With a tax, consumer surplus decreases to a smaller triangle (below the demand curve and above the new consumer price). Similarly, producer surplus also decreases to a smaller triangle (below the new producer price and above the supply curve).

The introduction of a tax also creates a deadweight loss. This represents economic activity that previously occurred but no longer does because of the tax, signifying lost welfare for both consumers and producers. Total surplus with a tax is less than without a tax.

The video then labels specific areas on the graph (A, B, C, D, E, F) to precisely break down how consumer surplus, tax revenue, producer surplus, and deadweight loss are composed both before and after the tax is implemented. This framework helps analyze the effects of taxation on surplus.