Effect of tariffs

Tariffs are a tax placed by the government on imports. They raise the price for consumers, lead to a decline in imports, and can lead to retaliation by other countries.

  • They could be a specific amount (e.g. £1 per unit.)
  • Or they could be an ad valorem tax (e.g. 10% of the price)

Tariffs are an important barrier to free trade; they are often imposed to protect domestic industry from cheap imports. However, it often leads to retaliation with other countries placing tariffs on their exports.



  • In this case, the tariff is P1-P2.
  • The tariff leads to a decline in imports. Imports were Q4-Q1. After the tariff, imports fall to Q3-Q2.
  • Consumer surplus falls by 1+2+3+4
  • Government raises tariff revenue of area 3
  • Domestic suppliers gain an increase in producer surplus of area 1
  • The net welfare loss  is (1+2+3+4) – (1+3) = 2+4

Effect of tariffs


  • Without any trade, the equilibrium price is £1.80 and a quantity of 40 million
  • With a tariff of £0.40, the price of imports will be £1.60.
  • The quantity of imports at £1.60 is (50-30) = 20 million.
  • With free trade (no tariffs) the price would be £1.20 and quantity bought 60 million.

Government tariff revenue

  • Tariff revenue = tariff × q. of imports (£0.40 × 20 million) = £ 8 million

Consumer surplus

This is the difference between the price consumers pay and the price they are willing to pay; therefore we find the area of the triangle between demand curve and price

  • With no trade = (£3.20 – £1.80 × 40) /2 = (£1.40 ×40)/2 = £28 million
  • After tariff – (£3.20 – £1.60) × 50)/2 = £40 million
  • With no tariff (free trade)- £3.20 – £1.20 × 60)/2 = £60 million
  • Tariffs reduce consumer surplus by £20 million

Diagram showing the effect of tariffs on consumer surplus effect-tariffs-on-consumer-surplus

Tariffs lead to a decline in consumer surplus of 1+2+3+4.

Producer surplus

producer-surplus The difference between the price and the price firms are willing to supply at (supply curve

  • With no trade (£1.80 – £0.5) × 40)/2 = £24 million
  • With tariff (£1.60-0.50) × 30)/2 = £16.5 million
  • With free trade and no tariff (£1.20-0.50 × 20)/2 = £6 million.
  • Tariffs increase producer surplus by £10.5 million

Welfare effect of tariffs = gain in producer surplus (£9 m) + gain in tariff revenue (£8m) – loss of consumer surplus £20m)

  • Therefore net welfare loss = £3 million

Reasons for imposing tariffs

  1. Raise revenue. If a country produces no oil, levying a tax on oil imports will raise money as people have no alternative put to pay the import tariff.
  2. Environmental. A tariff could be placed on goods who may have negative externalities. e.g.
  3. Protectionism. The most common reason for a tariff. Imposing import tariffs makes domestic firms more competitive.

Reasons for removing tariffs

  1. Trade liberalisation involves removing barriers to trade such as tariffs on imports.
  2. Free trade areas will have no tariffs between member states, though they may have a common external tariff if it is a customs union.
  3. Lower prices for consumers
  4. Increase specialisation and benefits from economies of scale.
  5. Theory of comparative advantage states net welfare gain from free trade.
  6. The reduction of tariffs leads to trade creation.

Winners and losers of tariffs


Examples of tariffs

The US has tariffs on many imports, such as:

  • Most vegetables 20% tariff.
  • Asparagus and sweetcorn – 21.5%. See: UTSC for more
  • EU has tariffs on many food imports.
  • See: Examples of protectionism

See also:

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