税の楔（ワッジ）とその負担者
導入済み| English | 意味 |
|---|---|
| specific tax/spəˈsɪfɪk tæks/ | 量税 |
| tax incidence/tæks ˈɪnsɪdəns/ | 租税帰着 |
A decision you can investigate
- A tax is legally collected from sellers, but buyers can still pay part of its economic burden.
- Legal responsibility for remitting the tax does not settle who bears the price change.
Build the explanation
- A specific tax 从量税 creates a wedge: buyer price Pb minus seller receipt Ps equals tax t. Demand depends on Pb; supply on Ps. Government receipts are t times the quantity actually traded after the tax.
- Relative elasticities determine the price burden in the competitive model. The less responsive side tends to bear more because it has fewer effective ways to leave or adjust. An ad-valorem tax instead changes the cash wedge with taxable value; use its stated tax base.
Work through the evidence
- Initially Qd=120−2P and Qs=2P give P=30,Q=60. With tax 12, Pb=Ps+12. Solve 120−2(Ps+12)=2Ps: Ps=24, Pb=36 and Q=48.
- Buyers pay 6 more per unit; sellers receive 6 less. Government revenue = 12 × 48 = 576, not 12 × 60. CS=½ × (60−36) × 48=576; PS=½ × 24 × 48=576. Including revenue gives 1728 versus initial gains of 1800: the lost trades create loss 72 here, assuming no externality correction.
税後の売主単価受取額はいくらか？
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供給曲線の販売者価格を用い、Pb = Ps + 12 とする。
課税後の収入は何か？
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12 × 48 = 576.
販売者が法的に納付する税金は、すべて販売者が負担しなければならない。
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市場価格の調整により、負担の一部を生じ物へ移転できる。
Test the limits
- The equal split comes from this symmetric model, not a universal tax rule. With relatively inelastic demand, buyers tend to bear more; with relatively inelastic supply, sellers tend to bear more. Perfectly inelastic supply is an extreme case of seller burden when demand is otherwise responsive.
- A tax can improve social allocation when it corrects an external cost; this no-externality arithmetic cannot establish that all taxes reduce welfare. Administration, evasion, revenue use and distribution also matter.
相対的に非弾力的な反応を示す側が通常より多くの負担を負うのはどちらか？
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調整の限界は、その側への経済的負担を増加させる。
Apply and explain your answer
- Why is government revenue calculated on 48 units rather than 60?
- Only the post-tax traded quantity is taxed under the stated per-unit rule.
用語とそれぞれの意味を結びつけよ。
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各用語を、その明示された経済的関係に用いること。
Use the terms precisely
- tax incidence 税负归宿: The distribution of the economic burden of a tax.
- specific tax: A fixed tax amount per unit of a good.
Initially Qd=120−2P and Qs=2P give P=30,Q=60. With tax 12, Pb=Ps+12. Solve 120−2(Ps+12)=2Ps: Ps=24, Pb=36 and Q=48. Buyers pay 6 more per unit; sellers receive 6 less. Government revenue = 12 × 48 = 576, not 12 × 60. CS=½ × (60−36) × 48=576; PS=½ × 24 × 48=576. Including revenue gives 1728 versus initial gains of 1800: the lost trades create loss 72 here, assuming no externality correction.
The equal split comes from this symmetric model, not a universal tax rule. With relatively inelastic demand, buyers tend to bear more; with relatively inelastic supply, sellers tend to bear more. Perfectly inelastic supply is an extreme case of seller burden when demand is otherwise responsive. A tax can improve social allocation when it corrects an external cost; this no-externality arithmetic cannot establish that all taxes reduce welfare. Administration, evasion, revenue use and distribution also matter.
A specific tax creates a wedge: buyer price Pb minus seller receipt Ps equals tax t. Demand depends on Pb; supply on Ps. Government receipts are t times the quantity actually traded after the tax.