The TIR Customs transit system is based on 6 essential principles, or basic requirements – the 6 pillars of the TIR System. These are :

• Goods should travel in secure vehicles or containers;
• Throughout the journey, duties and taxes at risk should be covered by an internationally valid guarantee;
• Goods should be accompanied by an internationally accepted customs document – the TIR Carnet, opened in the country of departure and serving as a customs control document in the countries of departure, transit and destination;
• Customs control measures taken in the country of departure should be accepted by all countries of transit and destination;
• Access to the TIR procedure shall be dependent on prior authorisation by national authorities (Customs).
• The sixth principle, SafeTIR was ratified in August 2006 (as Annex 10 to the TIR Convention). SafeTIR information should be sent by customs to confirm the unloading of goods on termination of a TIR operation.

1. Secure Vehicles or Containers

Goods are carried in containers or load compartments that are constructed so that :

• There is no access to the interior after being externally sealed with a Customs seal; and
• If tampered with, this will be clearly visible.

The TIR Convention sets out technical standards of construction and approval procedures.

If the container or load compartment meets the requirements, national inspection/approval authorities (usually Customs) issue 'approval certificates'. An approval certificate is valid for two years and can be renewed.

Goods may only be carried under a TIR Carnet if the sealed container or load compartment has a valid approval certificate, unless "heavy and bulky goods" are being transported.

2. International Guarantee Chain

If goods are not transported and delivered securely to the Customs at destination, the TIR holder may be liable for Customs duties and taxes payable within countries of transit.

The TIR System ensures that customs duties and taxes at risk are covered for the duration of the transit operation. The national guaranteeing association acts as guarantor if the customs debt cannot be recovered from the TIR holder or other persons that are directly liable.

In every country where TIR operates there is an Association representing the interests of the transport sector.

This National Association is authorised by the Customs administration of that country to guarantee up to a fixed amount any customs duties or taxes that may become due to the national customs administration, in the course of a TIR operation.

The National Association's guarantee extends to TIR operations using TIR Carnets issued by Associations in other countries.

Each National Issuing and Guaranteeing Association is contractually bound to the IRU and is thus a participant in the International Chain of Guarantee.

3. TIR Carnet

The TIR Carnet is an internationally standardised customs document used to :

• Give proof of the existence of an international 'guarantee'
• Facilitate customs control of the transit movement
• Act as evidence of the termination of each TIR operation

The TIR Carnet is a strictly accountable document and there are strict rules for the secure handling of TIR Carnets.

• Each authorized National Association issues TIR Carnets to approved transport companies in its own country.
• TIR Carnets will only be accepted in authorised Customs offices.

4. Reciprocal Recognition of Customs Controls

The principle is :

Customs in the country of departure take control measures, such as :

• Checking the condition (security) of the load compartment;
• Inspection of the goods; and
• Affixing seals to the vehicle's load compartments.

This check by the Customs office of departure is recognised and accepted by all other Customs offices during the transit operation.

This means Customs offices of transit do not routinely re-examine goods sealed and transported under TIR procedures.

5. Controlled Access by Customs and IRU

The TIR Convention sets out rules and conditions that provide for :

• National authorities (e.g. Customs) to authorise Associations to issue and guarantee TIR Carnets
• Transport companies to meet minimum conditions and requirements
• Transport companies to make a written commitment to the TIR Carnet Issuing Association, specifying responsibilities; and
• Transport companies to be authorised by Customs before gaining access.

6. Safe TIR Electronic Termination

The TIR Convention ratified a set of rules and conditions in August 2006 that provide for :

• National authorities (e.g. Customs) to send electronic information to the IRU to confirm the details on the termination of a TIR operation when goods have been unloaded
• This SafeTIR information to be processed and made available for viewing by Customs authorities, Associations, and other authorised persons
• Secure transmission and processes to guard the integrity of the SafeTIR information