Common Transit Convention (CTC) – how the UK and EFTA operate outside the EU customs union

After the United Kingdom left the European Union in 2021, trade between Poland and the UK became considerably more complex. One of the key mechanisms that enables the smooth flow of goods across multiple countries without paying duties multiple times or declaring goods at every border is the Common Transit Convention — CTC for short. This arrangement, for many years primarily associated with intra-European traffic, took on an entirely new significance after Brexit. The UK joined the CTC as a third country — just like Norway, Switzerland, Iceland and Liechtenstein, which belong to the EFTA area. As a result, goods sent from the United Kingdom to Poland can travel under a single transit declaration through all countries along the route, without stopping at each border for customs purposes or paying local duties. In this article we explain exactly what the CTC is, how it works in practice, which countries are members of the convention, and when it makes sense to use CTC transit rather than standard import and export procedures.

What is the Common Transit Convention and how does it work

The Common Transit Convention is an international agreement governing the customs transit procedure between signatory countries. Its purpose is to simplify the crossing of borders by goods that are not intended for consumption or sale in the transit countries — they are travelling to another destination.

The CTC is based on two types of procedure:

Procedure	Code	Application
External transit	T1	Goods from outside the EU customs territory or non-Union goods
Internal transit	T2	Goods with Union status moving through countries outside the EU

For Polish companies exporting to the UK, the most commonly used procedure after Brexit is T1 — goods leave Poland (or another EU country), travel through transit countries, and arrive in the United Kingdom under a single declaration opened at the office of departure and closed at the office of destination.

The guarantee mechanism is a key element of the CTC. To open a transit procedure, a customs guarantee is required — a financial security that will cover any customs duties in the event of irregularities during transit. The guarantee may be individual (for a single consignment) or comprehensive (renewable, for regular principals).

Which countries belong to the CTC — full list of members

The CTC covers a considerably wider group of states than just the EU. After Brexit, the following countries are members of the convention:

Group	Countries
European Union	27 EU member states
EFTA	Norway, Switzerland, Iceland, Liechtenstein
Other European countries	Turkey, Serbia, North Macedonia
Middle East	Jordan
Post-Brexit	United Kingdom (as a third country from 2021)

The UK joined the CTC on 1 January 2021, which means that despite not belonging to the EU customs union it can make use of the common transit procedures. This is one of the rare examples where Brexit did not require building a new system from scratch — the UK acceded to the existing convention on the same terms as Switzerland or Norway.

How the UK acceded to the CTC after Brexit

The United Kingdom was a party to the CTC as a member of the EU. After leaving the EU it had to join the convention independently as a third country — which it did by agreement with the other signatories.

Practical consequences of the UK's accession to the CTC: - Goods destined for the UK can travel under a T1 procedure opened, for example, in Poland - The UK recognises transit declarations issued in the NCTS system by other CTC countries - Customs guarantees issued in the EU are accepted in the UK and vice versa - A company holding the status of Authorised Consignee in the UK can receive goods at its own warehouse without needing to present them physically at a customs office

This arrangement significantly reduced the post-Brexit chaos at the border for companies using regular deliveries between Poland and the UK.

The difference between CTC, TIR and NCTS

Many companies confuse these terms. Here is an explanation of the differences:

Element	CTC (T1/T2)	TIR	NCTS
Type	Customs procedure	Convention with IRU guarantee	IT system
Documents	e-AD, MRN	TIR Carnet (paper)	Electronic
Coverage	CTC countries	TIR Convention countries (wider)	System supporting CTC
Guarantee	National / comprehensive	Through IRU / hauliers' association	—
Used for	UK↔EU, European transit	Routes to countries outside CTC	Registration of T1/T2 declarations

NCTS (New Computerised Transit System) is the IT platform through which all transit declarations under the CTC are submitted. In Poland it is administered by the National Revenue Administration. NCTS is not a procedure — it is a tool for the electronic processing of T1 and T2 procedures.

TIR, on the other hand, is a separate convention based on the physical TIR Carnet (the green booklet), issued by national transport associations affiliated with the IRU. TIR makes sense primarily for routes to countries that are not members of the CTC — for example to Russia (when that connection was active), Iran or Morocco.

How the UK → Germany → Poland route works under the CTC procedure

A practical example of CTC transit for the UK → DE → PL route:

Step 1: Opening the T1 procedure in the UK The exporter or their customs agent submits a T1 declaration in the NCTS system and receives an MRN (Movement Reference Number). The goods are placed under the transit procedure — from this point no duty may be charged on them in any intermediate country.

Step 2: Transit through Germany The vehicle carrying the goods crosses the EU border. Germany, as a transit country, does not require the opening of a new procedure — it is sufficient to present the MRN or the barcode from the T1 declaration. The customs authority may carry out a check, but does not collect duty.

Step 3: Closing the T1 in Poland On arrival at the place of destination (for example a warehouse in Poland), the customs authority or an authorised consignee closes the transit procedure. Only at this point may the goods be released to free circulation (following submission of an import declaration and payment of any applicable customs duties and VAT).

This entire process takes place without the vehicle stopping at the borders of transit countries for customs purposes — a significant time saving for carriers.

Roles of participants in the CTC procedure

Several key roles exist within the CTC procedure:

Principal (procedure holder) The person or company responsible for the correct completion of the transit. They must hold a customs guarantee. This is often a customs agency acting on behalf of the exporter or importer.

Declarant The entity actually submitting the declaration in NCTS — may be the same as the principal or may act as their representative.

Carrier The transport company physically conveying the goods. The carrier is not responsible for the guarantee, but is obliged to present transit documents on request from the customs authorities.

Consignee The entity receiving the goods at the place of destination. If they hold Authorised Consignee status, they may close the transit procedure at their own warehouse.

When CTC offers more value than standard import/export at each border

CTC delivers the greatest added value when:

1. Goods pass through more than one country — for example UK → France → Germany → Poland. Without the CTC, each border crossing would require separate formalities.

2. The company uses regular deliveries — holding a comprehensive guarantee and Authorised Consignee status drastically reduces customs processing time.

3. Delivery time is critical — the T1 procedure allows customs queues at the border to be avoided. Goods travel without stopping.

4. The route includes EFTA countries — for example export through Switzerland to EU countries or the UK. Without the CTC, Switzerland would require a separate procedure.

5. Consolidation of consignments — a single vehicle carrying goods for different consignees can travel under one T1 declaration.

For a single consignment with no transit through intermediate countries, standard export plus import may be simpler. However, for regular UK → PL routes passing through several countries, the CTC is the optimal solution.