Customs union

Topic: International Trade Policy, WTO and Intellectual Property · NCERT: Beyond NCERT

Meaning

A customs union is a group of countries that remove tariffs on trade among themselves and also charge one common external tariff (CET) on imports from non-members. A CET means every member charges the same customs duty on goods coming from outside the group.

It matters because it is the stage where members stop running separate trade policies towards the outside world. Because the outside tariff is the same everywhere, a customs union does not need internal rules of origin, while a free trade agreement (FTA) does.

Customs union = FTA (no tariffs inside) + common external tariff (same tariff outside)

Explanation

Where it sits in Balassa's stages (1961)

Bela Balassa ranked economic integration from shallow to deep. Each stage keeps everything from the stage before it and adds one new feature.

• Preferential trade agreement (PTA): tariffs are reduced, not removed, on an agreed list of goods. Examples: APTA, SAPTA.
• Free trade agreement (FTA): tariffs are removed on substantially all trade, but each member keeps its own external tariff. Examples: SAFTA, India–Sri Lanka.
• Customs union: FTA + common external tariff. Examples: SACU, Mercosur, EU (1968).
• Common market: customs union + free movement of labour and capital. Example: EU Single Market (1993).
• Economic union → Monetary union → Complete integration come after it.
• So a customs union is the third stage. It goes deeper than an FTA, but people and money still cannot move freely, as they can in a common market.

Why a common external tariff removes the need for rules of origin

• In an FTA, each member keeps a different outside tariff.
• Traders can bring goods in through the member with the lowest outside tariff.
• They then send the goods duty-free to the member with the higher tariff.

• This is called trade deflection. To stop it, an FTA needs rules of origin: rules that decide which country a product "comes from".

• In a customs union, the outside tariff is the same everywhere.

• Entering through one member instead of another saves nothing.

• So there is no reason to reroute goods, and internal rules of origin are not needed.

• The cost of this: no member can set its own import duties any more. Outside tariffs are decided jointly, and the group negotiates trade deals with other countries as one unit.

Legal basis in the WTO

• A customs union is discriminatory: members pay zero duty inside the group, while outsiders pay the CET. This breaks the most-favoured-nation (MFN) principle (a tariff cut given to one WTO member must be given to all).
• The WTO allows it under GATT Article XXIV (paras 4–10, clarified by the 1994 Understanding). This covers customs unions and free-trade areas in goods, and all members can use it [2].
• Customs unions count as regional trade agreements (RTAs), which means reciprocal trade deals notified to the WTO. Since the end of 2006, every RTA goes through the same WTO Transparency Mechanism review [1].

Welfare effects: trade creation vs trade diversion (Jacob Viner, 1950)

A customs union does not always make its members better off.

• Trade creation: a costly home producer is replaced by a cheaper partner. Welfare rises.
• Trade diversion: imports shift away from a cheaper outsider to a costlier partner, only because the partner now pays no duty. Welfare can fall.

Worked example: suppose India and Vietnam form a customs union, and the tariff on outsiders is 25%.

Supplier	Cost price	Price in India before	Price in India after the union
Domestic producer	₹110	₹110	₹110
China (outsider)	₹80	₹80 + 25% = ₹100 ← bought	₹100
Vietnam (partner)	₹90	₹90 + 25% = ₹112.5	₹90 ← bought

• Result: trade diversion. India switches from China, the cheapest producer, to Vietnam.
• The real cost to the world rises from ₹80 to ₹90, a loss of ₹10 per unit.
• The government loses ₹20 per unit in customs duty.

• Consumers gain ₹10 per unit (₹100 → ₹90).

• Rule of thumb: diversion is more likely when the common external tariff is high and the partner is not the lowest-cost producer in the world.

In India

• India is not a member of any customs union. Its deals are PTAs (APTA 1975, SAPTA 1995, India–Chile 2007, India–MERCOSUR 2009), FTAs (India–Sri Lanka 2000, SAFTA 2006, India–ASEAN TIGA 2010), and deeper CECA/CEPA-type deals.
• Because every member of an FTA keeps its own tariff, India has to rely on rules of origin.
• CAROTAR 2020 was notified on 21 August 2020 and came into force on 21 September 2020. It puts the burden of proving origin on the importer [3].

• Its aim is to stop Chinese goods coming in through ASEAN and other FTA partners. A customs union would not face this problem.

• India trades with customs unions as single partners.

• Mercosur is a customs union, and India has a PTA with it (2009).
• The EU has been a customs union since 1968. The India–EU FTA was concluded on 27 January 2026, and the EU became India's 22nd FTA partner [4].
• When the deal comes into force, EU tariffs of up to 10% on about US$33 bn of Indian exports fall to zero, helping textiles, leather, footwear, gems & jewellery and marine products [4].
• The same tariff applies across the whole EU, so Indian goods face one duty in every EU member.

Don't confuse with

• Free trade agreement (FTA): in an FTA, each member keeps its own outside tariff, so it needs rules of origin. A customs union has a common outside tariff, so it does not.
• Common market: a common market is a customs union plus free movement of labour and capital (e.g. EU Single Market, 1993). A customs union frees only the movement of goods.
• Preferential trade agreement (PTA): a PTA only reduces tariffs on a list of goods (e.g. SAPTA). A customs union removes internal tariffs and also sets a CET.
• Open regionalism: this is integration that does not raise barriers against outsiders (e.g. APEC, 1989). A customs union keeps a CET against outsiders.

Prelims Hooks

• Only a customs union (among the early Balassa stages) has a common external tariff. An FTA does not, and so it needs rules of origin to stop trade deflection.
• Balassa order (1961): PTA → FTA → Customs union → Common market → Economic union → Monetary union → Complete integration.
• Examples of customs unions: SACU, Mercosur, EU (1968). SAFTA and India–Sri Lanka are FTAs, not customs unions.
• WTO legal basis: customs unions and FTAs in goods are allowed under GATT Article XXIV [2]. Deals in goods among developing countries can use the Enabling Clause (1979), and services deals use GATS Art. V [2].
• Trade creation vs trade diversion is Jacob Viner (1950). "Building blocks vs stumbling blocks" and the "spaghetti bowl effect" are Jagdish Bhagwati.
• Trap: India–MERCOSUR (2009) is a PTA, even though Mercosur itself is a customs union.

Mains Points

• Why India prefers FTAs to a customs union:
• A customs union would force India to give up its own tariff policy. It could no longer protect sensitive farm and dairy products or use tariffs as an industrial policy tool.
• FTAs let India keep that freedom. The cost is complex rules of origin, CAROTAR-type enforcement [3], and the spaghetti bowl of overlapping rules.

• This trade-off explains India's choice of FTAs, CEPAs and TEPAs over deeper integration such as a South Asian customs union.

• Building block or stumbling block?

• A customs union with a high common external tariff raises the risk of trade diversion and hurts outsiders.

• When India negotiates with customs unions such as the EU (India–EU FTA, 2026 [4]), it wins access to the whole bloc on one tariff schedule. It also has to phase its own tariff cuts over 5, 7 or 10 years to protect domestic producers [4].

• Regional integration in South Asia (GS-II): SAFTA (2006) has stayed at the FTA stage. Moving to a customs union would need members to agree on a common tariff, which is politically hard given India–Pakistan tensions and the large gaps in members' tariff structures.

Related concepts

• Stages of economic integration
• Preferential trade agreement
• Free trade agreement
• Common market
• Economic union
• Monetary union
• Trading bloc
• Regional economic groupings
• Regionalism
• Open regionalism

Read more

• Regionalism: stages of integration, FTAs and rules of origin