Microeconomic Policy and Applications of Elasticity Review for AP Economics (page 2)
Review questions for this study guide can be found at:
Main Topics: Excise Taxes, Government Subsidies, Price Floors, Price Ceilings
Government occasionally imposes an excise tax on the production of a good or service. Because it is a per unit tax on production, the firm responds as if the marginal cost of producing each unit has risen by the amount of the tax. Graphically this results in a vertical shift in the supply curve by the amount of the tax. The reasons for this tax are usually twofold: (1) to increase revenue collected by the government and/or (2) to decrease consumption of a good that might be harmful to some members of society. For these reasons, tobacco is a good example of an excise tax. Can an excise tax on tobacco raise money for government? Can it deter people from smoking? Let's use our two extreme demand curves to see where these goals might, or might not, be achieved, and how the price elasticity of demand plays a critical role on where the burden, or incidence, of the tax rests. Economists commonly express the incidence of the tax as the percentage of the tax paid by consumers, in he form of a higher price.
Demand is Perfectly Inelastic
If the demand for cigarettes is perfectly inelastic (Ed = 0) then the demand curve (D0) is vertical. With an untaxed supply (S0) of cigarettes, the initial price of a pack of cigarettes is P0 and Q0 packs of cigarettes are consumed every day. If a per unit tax of T is imposed on the producers of cigarettes, the supply curve shifts upward by T. Be careful! This is not an "increase in supply"! Because the demand is perfectly inelastic, the equilibrium quantity remains at Q0, but the new price rises to P0 +T. Total dollars spent on cigarettes increases from P0 * Q0 to (P0+T) * Q0. The revenue collected by the government is equal to the area of the rectangle T * Q0.
Did our excise tax accomplish our goals? Since quantity remained constant, the tax did nothing to decrease the harmful effects of smoking in society and only increased tax revenues for the government. In fact, because the quantity demanded did not fall, this scenario creates the largest revenue rectangle collected by the government. Who paid the burden of the tax? In Figure 7.7, you can see that the entire tax was paid by consumers in the form of a new price exactly equal to the old price plus the tax.
Demand is Perfectly Elastic
Figure 7.8 shows that if the demand for cigarettes is perfectly elastic (Ed = ∞), then the demand curve (D0) is horizontal. With an untaxed supply (S0) of cigarettes, the initial price of a pack of cigarettes is P0 and Q0 packs of cigarettes are consumed daily. The per unit tax of T shifts the supply curve upward by T, but with a perfectly elastic demand curve, the equilibrium price of cigarettes does not change, while equilibrium quantity demanded falls to Q1. Total spending by consumers falls to the area P0 * Q1. Tax revenue for the government is a much smaller rectangle T * Q1.
Who paid for the tax in this case? Because the price of a pack of cigarettes did not increase after the tax, it was not the consumers. Each producer receives a price of P0 but must then pay T to the government so the net price received from each pack of cigarettes is (P0 – T). So the producer pays the entire share of the tax when demand is perfectly elastic. Compared to the perfectly inelastic scenario, the government collected much fewer tax revenue dollars, but the maximum decrease in harmful cigarette consumption is a definite plus.
With these two extreme cases as benchmarks, we can conclude that as demand is more inelastic, consumers pay a higher share of an excise tax. Government revenues from the excise tax increase with inelastic demand, but the goal of decreasing consumption sees only minimal success. Table 7.3 summarizes the effects of a higher excise tax and how these depend upon the price elasticity of demand.
Since cigarette demand is usually inelastic, significant improvements in the health of consumers is probably not the primary outcome of higher excise taxes, although they would seem to be effective revenue generating devices. Ironically, although the tax is actually imposed on suppliers of cigarettes, most of the burden of the tax falls upon consumers. Figure 7.9 illustrates an inelastic demand for cigarettes, before and after an excise tax.
The Role the Supply Curve Plays in the Impact of an Excise Tax
We have seen that the greater the price elasticity of demand, the smaller the portion of the tax paid by consumers. It is also true that the price elasticity of supply plays a role in determining how much a tax will cause the price to increase and therefore helps to determine which group, consumers or producers, pay a higher burden of a tax.
It again helps to see if we look at two extremes: a perfectly elastic supply curve and a perfectly inelastic supply curve.
A perfectly elastic, or horizontal, supply curve tells us that even a very small change in the price will cause an infinitely large change in the quantity supplied. A per unit tax T imposed on suppliers causes this horizontal supply curve to shift upward by the amount of the tax. In Figure 7.10, you can see that the new equilibrium price is exactly T higher than the old price P0 so consumers pay the entire burden of the tax. The equilibrium quantity decreases from Q0 to Q1 and the government collects tax revenue equal to T*Q1.
A perfectly inelastic, or vertical, supply curve illustrates the special case where any change in the price creates absolutely no change in quantity supplied. Figure 7.11 shows that in this case, the supply curve cannot vertically shift. At the equilibrium quantity Q0, suppliers would like to charge a higher price than P0, but any price above P0 creates a surplus, and this surplus will clear only at the equilibrium price P0. Therefore the firms must pay T to the government for each of the Q0 units that are sold and consumers continue to pay the original price of P0. In this special case, producers pay the entire burden of the tax because, after paying the tax, they receive only (P0 – T) on each unit. The government collects total revenue equal to T*Q0.
Table 7.4 summarizes the effects of a higher excise tax and how these depend upon the price elasticity of supply.
By now you are probably wondering: "How can I keep all of this straight?" If we consider the extreme cases of perfectly elastic and perfectly inelastic demand and supply curves, we can draw some general conclusions.
- As the price elasticity of demand falls, and the price elasticity of supply rises, the greater the consumer's share of a per unit excise tax. Why? Because this describes a situation where the consumer response to a higher price is negligible and the producer's response is sizeable. The group that has the best ability to respond to the higher post-tax price is going to make out better.
- Conversely, as the price elasticity of demand rises, and the price elasticity of supply falls, the greater the producer's share of a per unit excise tax.
Loss to Society
There is also a cost to society when an excise tax is imposed on a competitive market. In the hypothetical soda market depicted in Figure 7.12, the equilibrium quantity is 100 and the equilibrium price is $1. At this point, the marginal benefit to society exactly equals the marginal cost and net benefit; total welfare (combined consumer and producer surplus) is the greatest. When a $l excise tax is imposed, the price of sodas increases to $1.80 and the amount of sodas consumed decreases to 80. The government collects $80 = $1 * 80 in tax revenue. With the tax, consumers and producers demand and supply 20 fewer units than without the tax. For these 20 units that go unproduced, the marginal benefit to consumers exceeds the marginal costs to producers. The fact that these 20 units go unproduced and unconsumed results in an inefficient outcome. The triangle labeled DWL used to be earned by society in the form of consumer and producer surplus. With the excise tax, society loses this area; it goes to no one. Economists call this area dead weight loss (DWL) or the net benefit sacrificed by society when such a per unit tax is imposed. Since the key to dead weight loss is a large decrease in quantity below the untaxed outcome, the area of dead weight loss to society increases as the demand or supply curves get more elastic.
Note: Taxes such as these are not the only sources of distortions away from market efficiency. For example, production often generates pollution (a negative externality), which creates a situation where harmful spillover costs are incurred by third parties. Left unregulated, these costs are not captured by the market price and the market will not produce the "correct" amount of a good. These sources of inefficiency, or market failures, are addressed in Chapter 11.
- Taxes create lost efficiency by moving away from the equilibrium market quantity where MB = MC to society.
- The area of dead weight loss (triangle DWL) increases as the quantity moves further from the competitive market equilibrium quantity.
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