Application:
The Costs of Taxation
应用: 税收的成本
Chapter 8
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Application: The Costs of Taxation
Welfare economics is the study of how
the allocation of resources affects
economic well-being.
n Buyers and sellers receive benefits from taking
part in the market.
n The equilibrium in a market maximizes the
total welfare of buyers and sellers.
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应用: 收税的成本
福利经济学——研究资源配置如何影
响经济福利 。
n 买者和卖者可以从参与市场活动中获得利
益。
n 市场均衡可以使买者和卖者的总利益最大
化。
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THE DEADWEIGHT LOSS OF TAXATION
税收的无谓损失
How do taxes affect the
economic well-being of
market participants?
税收如何影响市场参与
者的经济福利?
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THE DEADWEIGHT LOSS OF TAXATION
It does not matter whether
a tax on a good is levied on
buyers or sellers of the
good…the price paid by
buyers rises, and the price
received by sellers falls.
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税收的无谓损失
一种物品的税收是向买者
征收还是向卖者征收是不
重要的…，结果都是买者
支付的价格上升，而卖者
得到的价格下降。
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The Effects of a Tax...
Price
0 QuantityQuantity
without tax
Supply
Demand
Price
without tax
Price buyers
pay
Quantity
with tax
Size of tax
Price sellers
receive
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税收效应
价格
0 数量税前的需求量
供给
需求
没有税收
时的价格
买者支付
的价格
税后的需求
量
税收规模
卖者得到
的价格
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How a Tax Affects Market Participants
uA tax places a wedge between the price
buyers pay and the price sellers receive.
uBecause of this tax wedge, the quantity
sold falls below the level that would be
sold without a tax.
uThe size of the market for that good
shrinks.
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税收如何影响市场参与者
u税收在买者支付的价格和卖者得到的价
格之间打入了一个楔子。
u由于这种税收楔子，销售量低于没有税
收时应该达到的水平。
u对一种物品征税使这种物品的市场规模
收缩。
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Tax Revenue 税收收入
T = the size of the tax
T=税收规模
Q = the quantity of the good sold
Q=物品销售量
TQ = the government’s tax revenue
TXQ=政府的总税收收入
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Tax Revenue...
Price
0 QuantityQuantity
without tax
Supply
Demand
Price sellers
receive
Quantity
with tax
Size of tax (T)
Quantity
sold (Q)
Tax
Revenue
(T x Q)
Price buyers
pay
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税收收入...
价格
0 数量税前数量
供给
需求
卖者得到
的价格
税后数量
税收规模 (T)
销售量 (Q)
税收收入
(T x Q)
买者支付
的价格
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How a Tax Affects Welfare...
Quantity0
Price
Demand
Supply
Q1
A
B
C
F
D E
Q2
Tax reduces consumer surplus by (B+C)
and producer surplus by (D+E)
Tax revenue = (B+D)
Deadweight Loss = (C+E)
Price
buyers
pay = PB
P1
Price
without
tax
=
PSPrice
sellers
receive
=
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税收如何影响福利...
数量0
价格
需求
供给
Q1
A
B
C
F
D E
Q2
征税减少了消费者剩余 (用面积B+C代表)和
生产者剩余 (用面积D+E代表)
税收 = (B+D)
无谓损失 = (C+E)
买者支
付的价
格 = PB
P1
没有税收
时的价格 =
PS卖者得
到的价
格
=
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How a Tax Affects Market Participants
税收如何影响市场参与者
n Changes in Welfare 福利的变化
äA deadweight loss is the fall in total
surplus that results from a market
distortion, such as a tax.
无谓损失——市场扭曲（比如收税）引
起的总剩余减少。
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How a Tax Affects Welfare
Without Tax With Tax Change
Consumer Surplus A + B + C A - (B + C)
Producer Surplus D + E + F F - (D + E)
Tax Revenue none B + D + (B + D)
Total Surplus A + B + C + D + E + F A + B + D + F - (C + E )
The area C+E shows the fall in total surplus and
is the deadweight loss of the tax.
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税收如何影响福利
没有税收时 有税收时 变动
消费者剩余 A + B + C A - (B + C)
生产者剩余 D + E + F F - (D + E)
税收收入 无 B + D + (B + D)
总剩余 A + B + C + D + E + F A + B + D + F - (C + E )
C+E 的面积表示总剩余减少，而且是税收的
无谓损失。
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How a Tax Affects Welfare
The change in total welfare includes:
uThe change in consumer surplus,
uThe change in producer surplus,
uThe change in tax revenue.
uThe losses to buyers and sellers exceed
the revenue raised by the government.
uThis fall in total surplus is called the
deadweight loss.
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税收如何影响福利
总福利的变动包括：
u消费者剩余的变动,
u生产者剩余的变动,
u税收收入的变动。
u买者和卖者由税收受到的损失大于政
府筹集到的收入。
u无谓损失——税收引起的总剩余减少。
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Deadweight Losses and the Gains from Trade
无谓损失与贸易的好处
Taxes cause deadweight losses because
they prevent buyers and sellers from
realizing some of the gains from trade.
税收引起无谓损失是因为它使买者与卖者
不能实现某些贸易的好处。
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The Deadweight Loss...
Quantity0
Price
Demand
Supply
Q1
PB
Price = P1
without tax
P
S
Q2
Size of tax
Lost gains
from trade
Cost to
sellers
Value to
buyers
Reduction in quantity due to the tax
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无谓损失...
数量0
价格
需求
供给
Q1
PB
没有税收 P1
时的价格
P
S
Q2
税收规模
损失的贸易好处
卖者的
成本
买者的评价
由于税收引起的数量减少
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Determinants of Deadweight Loss
What determines whether the deadweight
loss from a tax is large or small?
uThe magnitude of the deadweight loss
depends on how much the quantity
supplied and quantity demanded
respond to changes in the price.
uThat, in turn, depends on the price
elasticities of supply and demand.
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无谓损失的决定因素
什么因素决定税收的无谓损失是大还
是小？
u无谓损失的大小决定于供給量和需求
量对价格变动的反应程度。
u也就是说，决定于供给和需求的价格
弹性。
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Tax Distortions and Elasticities...
税收扭曲与弹性…
Quantity 数量
Price
Demand 需求
Supply
供给
0
When supply is
relatively inelastic,
the deadweight loss
of a tax is small.
当供给比较缺乏弹性时，
税收的无谓损失小。
(a) Inelastic Supply
缺乏弹性的供给
Size
of tax
税收
规模
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Tax Distortions and Elasticities...
税收扭曲与弹性…
Quantity 数量
Price
价格
Demand 需求
Supply
供给
0
Size
of tax
税收
规模
When supply is
relatively elastic,
the deadweight loss
of a tax is large.
当供给比较富有弹性时，
税收无谓损失大。
(b) Elastic Supply 富有弹性的供给
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Tax Distortions and Elasticities...
税收扭曲与弹性…
Quantity 数量
Price
价格
Demand
需求
Supply 供给
0
When demand is
relatively inelastic,
the deadweight loss
of a tax is small.
当需求比较缺乏弹性时，
税收的无谓损失小。
(c) Inelastic Demand 缺乏弹性的需求
Size
of tax
税收
规模
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Tax Distortions and Elasticities...
税收扭曲与弹性…
Quantity 数量
Price
价格
Demand 需求
Supply 供给
0
Size
of tax
税收
规模
When demand is
relatively elastic,
the deadweight loss
of a tax is large.
当需求比较富有弹性时，
税收的无谓损失大。
(d) Elastic Demand 富有弹性的需求
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Determinants of Deadweight Loss
无谓损失的决定因素
The greater the elasticities of demand
and supply:
供给和需求的弹性越大：
u the larger will be the decline in
equilibrium quantity and,
均衡数量下降的越多，
u the greater the deadweight loss of a tax.
税收的无谓损失也就越大。
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The Deadweight Loss Debate
无谓损失的争论
Some economists argue that labor
taxes are highly distorting and believe
that labor supply is more elastic.
一些经济学家认为劳动税引起严重扭
曲，他们相信劳动供给是较为富有弹
性的。
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The Deadweight Loss Debate
Some examples of workers who may
respond more to incentives:
uWorkers who can adjust the number of
hours they work
uFamilies with second earners
uElderly who can choose when to retire
uWorkers in the underground economy
(. those engaging in illegal activity)
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无谓损失的争论
一些对激励反应较大的工人:
u许多可以调整工作时间长短的工人
u一些有第二个赚钱人的家庭
u许多老年人可以选择什么时候退休
u从事地下经济活动的工人 (如从事非法
活动的人)
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Deadweight Loss and Tax Revenue as Taxes Vary
无谓损失和税收收入随税收变动而变动
With each increase in the tax rate, the
deadweight loss of the tax rises even
more rapidly than the size of the tax.
随着每一次税率增加，税收无谓损失的
增加要快于税收规模。
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Deadweight Loss and Tax Revenue...
无谓损失与税收收入…
PB
Quantity 数量Q20
Price
价格
Q1
Demand 需求
Supply 供给
Tax revenue
税收收入PS
Deadweight
Loss 无谓损失
(a) Small Tax 小额税
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Demand 需求
Supply 供给
Tax
Revenue
税收收入
PB
Quantity 数量Q20
Price
价格
Q1
PS
Deadweight
Loss 无谓损失
Deadweight Loss and Tax Revenue...
无谓损失与税收收入…
(b) Medium Tax 中额税
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T
a
x
r
e
v
e
n
u
e
PB
Quantity 数量Q20
Price 价格
Q1
Demand 需求
Supply 供给
PS
Deadweight
loss
Deadweight Loss and Tax Revenue...
无谓损失与税收收入…
(c) Large Tax 大额税
税
收
收
入
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Deadweight Loss and Tax Revenue
uFor the small tax, tax revenue is
small.
uAs the size of the tax rises, tax
revenue grows.
uBut as the size of the tax continues to
rise, tax revenue falls because the
higher tax reduces the size of the
market.
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无谓损失与税收收入
u收小额税时，税收收入少。
u随着税收规模增加，税收收入增加。
u但随着税收规模继续增加，税收收入
反而减少，这是因为较高的税收规模
减少了更多的市场规模。
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Deadweight Loss and Tax Revenue as Taxes Vary
无谓损失和税收收入随着税收规模而变动
(a) Deadweight Loss
无谓损失
Deadweight
Loss
无谓损失
0
Tax Size 税收规模
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Deadweight Loss and Tax Revenue as Taxes Vary
无谓损失和税收收入随着税收规模而变动
(b) Revenue (the Laffer curve)
税收收入（拉伐曲线）
Tax
Revenue
税收收入
0 Tax Size 税收规模
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Deadweight Loss and Tax Revenue
as Taxes Vary
uAs the size of a tax increases, its
deadweight loss quickly gets larger.
uBy contrast, tax revenue first rises
with the size of a tax; but then, as the
tax gets larger, the market shrinks so
much that tax revenue starts to fall.
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无谓损失和税收收入随税收规模而变动
u随着税收规模提高，无谓损失迅速
增大。
u相反，随着税收规模提高，税收收
入先是增加，然后随着税收规模越
来越大，市场规模收缩非常之大，
以至于收入开始减少。
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The Laffer Curve and
Supply-Side Economics
uThe Laffer curve depicts the relationship
between tax rates and tax revenue.
uSupply-side economics refers to the views
of Reagan and Laffer who proposed that
a tax cut would induce more people to
work and thereby have the potential to
increase tax revenues.
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拉伐曲线与供给学派经济学
u拉伐曲线 说明税率和税收之间的关
系。
u供给学派经济学 是指里根和拉伐的
观点，他们认为减税能激励更多的
人工作，或许甚至可能增加税收。
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Summary 小结
uA tax on a good reduces the welfare
of buyers and sellers of the good.
And the reduction in consumer and
producer surplus usually exceeds the
revenues raised by the government.
向一种物品征税减少了该物品买者与卖
者的福利，而且消费者和生产者剩余的减
少通常超过了政府筹集到的收入。
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Summary 小结
uThe fall in total surplus – the sum of
consumer surplus, producer
surplus, and tax revenue – is called
the deadweight loss of the tax.
总剩余（消费者剩余、生产者剩余
和税收收入之和）的减少被称为税
收的无谓损失。
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Summary
uTaxes have a deadweight loss
because they cause buyers to
consume less and sellers to produce
less.
uThis change in behavior shrinks
the size of the market below the
level that maximizes total surplus.
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小结
u税收有无谓损失是因为它引起买者
少消费和卖者少生产。
u这种行为变化使市场规模缩小到使
总剩余最大化的水平之下。
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Summary
uAs a tax grows larger, it distorts
incentives more, and its deadweight
loss grows larger.
uTax revenue first rises with the size
of a tax.
uEventually, however, a larger tax
reduces tax revenue because it
reduces the size of the market.
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小结
u随着税收增加，它对激励的扭曲
越来越大，而且无谓损失也越来
越大。
u税收收入起初随着税收规模增加
而增加。
u但是，最终由于高税收减少了市
场规模，也就减少了税收收入。
