Price limits, tax and subsidy choices
| English | Français |
|---|---|
| binding price ceiling/ˈbaɪndɪŋ praɪs ˈsiːlɪŋ/ | binding price ceiling |
| guaranteed minimum price/ˌɡærənˈtiːd ˈmɪnɪməm praɪs/ | guaranteed minimum price |
A decision you can investigate
- A low legal maximum may make a listed price affordable while leaving too few units available. A guaranteed minimum may support producers while requiring public purchases.
- The price rule and how it is enforced determine the outcome.
Build the explanation
- A maximum price below equilibrium can create excess demand; a minimum above equilibrium can create excess supply. A non-binding limit does not change the competitive equilibrium. Rationing, queues, quality changes or informal markets may follow; a posted low price does not ensure access.
- A guaranteed minimum differs from a legal floor without purchases: the government may buy surplus to sustain the price. Storage, disposal and incentives to produce then matter. A specific tax is fixed per unit; an ad-valorem tax is a percentage of a stated value. A subsidy may lower the buyer price and raise the supplier receipt. Use the earlier two-price incidence models rather than assuming who legally pays receives the whole burden or benefit.
Work through the evidence
- For Qd=120−2P and Qs=2P, equilibrium isP 30,Q 60. A maximumP 20 gives Qd 80,Qs 40: shortage 40, with at most 40 units supplied under the static model. A guaranteed minimumP 40 gives Qd 40,Qs 80: surplus 40. If government buys all surplus at 40, expenditure=40 ×40=1600; consumers buy 40 and government buys 40.
- A specific tax of 3 on a unit priced 20 is 15% of that value; a 10% ad-valorem tax is 2 at value 20 but 3 at value 30. A corrective tax should respond to the marginal external harm, not simply reproduce the same percentage for every context. In the earlier constant-MEC 20 production case, a specific tax 20 can move private output from 40 toward the modeled social 30.
What is the modeled shortage under the price 20 ceiling?
Demand 80 minus supply 40 equals 40.
How much does government spend buying all surplus at the guaranteed price 40?
It buys 40 surplus units at 40, not all 80 units.
Every statutory price ceiling necessarily causes a shortage.
A maximum at or above the unregulated equilibrium can be non-binding.
Test the limits
- A housing rent ceiling can help sitting tenants while reducing maintenance or new supply, depending on rules and elasticities. Energy or transport price caps can protect users but may weaken conservation incentives or require funded supplier compensation. Agricultural or commodity guarantees can stabilize producer receipts while encouraging surplus and costly storage.
- Health or education subsidies may address external benefits or access, but eligibility, opportunity cost and provider capacity matter. Compare targeted transfers, provision or regulation where appropriate. A floor without a purchasing guarantee need not result in 80 units actually sold.
Which describes an ad-valorem tax?
Its amount varies with the stated value base.
Apply and explain your answer
- Why is 1600 a government purchase cost rather than the total social cost of the minimum-price policy?
- It records money spent on the 40 surplus units; storage, opportunity costs, distribution and net social gains/losses require separate analysis.
Match the terms to their meanings.
Use each term for its stated economic relationship.
Use the terms precisely
- binding price ceiling 有约束力的最高限价: A maximum below the otherwise-clearing price, restricting legal price adjustment.
- guaranteed minimum price 保证最低价格: A supported minimum at which eligible supply is purchased under the stated guarantee.
For Qd=120−2P and Qs=2P, equilibrium isP 30,Q 60. A maximumP 20 gives Qd 80,Qs 40: shortage 40, with at most 40 units supplied under the static model. A guaranteed minimumP 40 gives Qd 40,Qs 80: surplus 40. If government buys all surplus at 40, expenditure=40 ×40=1600; consumers buy 40 and government buys 40. A specific tax of 3 on a unit priced 20 is 15% of that value; a 10% ad-valorem tax is 2 at value 20 but 3 at value 30. A corrective tax should respond to the marginal external harm, not simply reproduce the same percentage for every context. In the earlier constant-MEC 20 production case, a specific tax 20 can move private output from 40 toward the modeled social 30.
A housing rent ceiling can help sitting tenants while reducing maintenance or new supply, depending on rules and elasticities. Energy or transport price caps can protect users but may weaken conservation incentives or require funded supplier compensation. Agricultural or commodity guarantees can stabilize producer receipts while encouraging surplus and costly storage. Health or education subsidies may address external benefits or access, but eligibility, opportunity cost and provider capacity matter. Compare targeted transfers, provision or regulation where appropriate. A floor without a purchasing guarantee need not result in 80 units actually sold.
A maximum price below equilibrium can create excess demand; a minimum above equilibrium can create excess supply. A non-binding limit does not change the competitive equilibrium. Rationing, queues, quality changes or informal markets may follow; a posted low price does not ensure access.