Office of transit and the guarantee in transit through third countries

Four offices in the transit procedure

A movement under the common transit procedure (CTC/NCTS) passes through several kinds of customs office. It is worth distinguishing their roles:

• Office of departure — this is where the movement begins: the declaration is accepted, the NCTS issues the MRN number and grants release for transit.
• Office of transit — the customs office at the border through which the goods enter or leave the territory of the next party to the convention during the journey.
• Office of destination — this is where the movement ends: the arrival of the goods is notified and the procedure is discharged.
• Office of guarantee — responsible for guarantees; in the UK this function is performed by an HMRC team (the Central Community Transit Office, CCTO), which issues authorisations and guarantee numbers.

The office of transit — what it is and when you pass through it

The office of transit is the customs office at the border through which goods placed under common transit enter or leave the territory of a new party to the convention. In other words: it appears at every crossing of the external border of the common transit area. In practice this includes, among others, the EU–UK border (in both directions), borders with EFTA countries or transit through a country outside the area. If the whole journey takes place within a single customs territory (e.g. entirely within the EU), there is no office of transit to pass through.

What the driver does at the border

At the office of transit you must present the movement — that is, show the MRN number. How depends on the port:

• Ports operated by GVMS (e.g. Dover, Folkestone, Eurotunnel) — the MRN is passed electronically via GVMS before clearance; the driver does not need a paper document.
• Ports without GVMS — the MRN must be shown as a barcode or a paper Transit Accompanying Document (TAD).

Border services (Border Force in the UK or the competent office on the EU/EFTA side) verify that the declaration data matches, whether the prescribed route has been followed where applicable, and the integrity of the customs seals. After a successful check the movement continues.

The guarantee in common transit

The second key element is the guarantee. The requirement to hold one follows from the nature of transit: since the goods travel with duty and VAT suspended, there must be security for the customs debt that would arise if the load did not reach the office of destination correctly. The guarantee must cover the full possible amount of the debt across all movements open at the same time — which is why the system keeps track of current usage of the limit. We describe this mechanism in more detail in our article on the CTC transit guarantee.

Types of guarantee

• Comprehensive guarantee (in the UK: CCG) — covers multiple movements up to a reference amount; the standard for operators that use transit regularly.
• Guarantee waiver — for authorised operators, with the reference amount reduced even down to zero.
• Individual guarantee — for a single movement, for instance where someone moves goods under transit only occasionally or has to cover an exceptionally high debt.

Holders of a comprehensive guarantee may — once the conditions are met (among others, no serious customs breaches and regular use of the procedure) — apply for a reduction in the required amount: to 50%, to 30% or a full waiver. The details and conditions are set out on gov.uk.

GRN and access code — without them the declaration will not go through

After the guarantee is authorised, the holder receives two items from HMRC: the GRN (Guarantee Reference Number) — the guarantee reference number — and an access code. Both values are entered with every transit declaration in the NCTS; the system validates them against the declarant's data (e.g. the EORI number) and rejects the declaration if there is an error. Using another operator's guarantee requires the office of guarantee to set up a separate access code.

Releasing the guarantee after the movement is discharged

The guarantee is not released until the goods are recorded as "arrived" at the office of destination and the movement is correctly discharged. Once discharged, the amount returns to the available limit. If a movement stays open (an undischarged transit movement), part of the guarantee is blocked until the matter is resolved — and exhausting the limit makes it impossible to start further movements.

NCTS Phase 5 — what changed

With the rollout of the NCTS Phase 5 final state (for the parties to the convention, from 21 January 2025), several important things changed regarding offices of transit and the handling of movements:

• The paper accompanying document (TAD) is no longer mandatory — the MRN can be presented electronically (via GVMS, on a phone, or as a printed barcode).
• The office of transit receives an electronic record in advance of the expected movement, so it can compare the MRN presented with the announced data.
• Incidents en route (e.g. a broken seal, transhipment, a deviation from the route) are recorded in the system in real time by the competent office.
• Among other things, mandatory commodity codes (the first 6 digits of the HS code) for items in the declaration have been introduced.

We write more about the system change itself in our article on NCTS Phase 5.

What happens when something goes wrong

If an incident occurs en route (a data discrepancy, a breach of seals, transhipment), it must be reported to the nearest customs office. For minor irregularities the office records the event, applies new seals if needed and confirms the movement. For serious ones — for example a significant shortage of goods — the movement may be ended at the office where the incident occurred, which then becomes the actual office of destination. Smooth use of the procedure is helped by simplifications: authorised consignor and authorised consignee status lets you open and close movements at approved places, without a physical visit to a customs office.

The role of the customs agent

Correctly identifying the offices of transit along the route, setting up and managing the guarantee (GRN, access code, limit) and discharging movements on time are areas where a costly mistake is easy to make — and a blocked guarantee can hold up further movements. Easy Clearance handles transit on the UK side: opening and closing NCTS movements, guarantees and border documentation. Get in touch if you are planning transit across the borders of the common transit area.

What follows from the current rules

The office of transit is the customs office at the border through which goods under common transit enter or leave the territory of the next party to the convention — in practice it appears at every crossing of the border of the common transit area, e.g. EU–UK. At the border you present the MRN (via GVMS or as a barcode/TAD). The second pillar of the procedure is the guarantee securing the customs debt: in the UK most often a comprehensive guarantee (CCG) with a GRN number and an access code, with reductions possible for authorised operators. The guarantee is released only after the movement is correctly discharged. NCTS Phase 5 (the final state from 21 January 2025) removes the requirement for a paper TAD, introduces electronic notification of offices of transit and the recording of incidents in real time. This article reflects the position as at 2026-06-13. Contact a customs agent before taking any action.

FAQ — frequently asked questions

What is the office of transit?

It is the customs office at the border through which goods placed under common transit enter or leave the territory of the next party to the convention. The movement (the MRN) is presented there, and the NCTS records the border crossing. It appears at every crossing of the external border of the common transit area, e.g. EU–UK.

When do you have to pass through the office of transit?

Every time goods under common transit cross the border between two parties to the convention — for example entering or leaving the UK, the EU–EFTA border or transit through a country outside the area. At the border you show the MRN (electronically via GVMS or as a barcode / TAD document).

What is the guarantee for in common transit?

It secures the customs debt (duty, VAT, excise) that could arise if the goods did not reach the office of destination correctly. It must cover the full possible amount of the debt across all open movements. Once the movement is correctly discharged the guarantee is released.

What are the GRN and the access code in the NCTS?

The GRN (Guarantee Reference Number) is the guarantee reference number, and the access code is the password linked to it. Both are entered in the transit declaration in the NCTS — without the correct pair the declaration is rejected. In the UK, guarantees are issued by an HMRC team (CCTO).

What did NCTS Phase 5 change for offices of transit?

In the final state (from 21 January 2025) the paper accompanying document is no longer mandatory — the MRN can be presented electronically. The office of transit also receives an electronic record of the expected movement in advance, and incidents en route are recorded in the system in real time.

Official sources

• Transit Manual Supplement — Common/Union Transit (offices of transit) — gov.uk — GOV.UK
• Transit Manual Supplement — Guarantees (CCG, GRN, reductions) — gov.uk — GOV.UK
• Apply for a customs comprehensive guarantee to cover customs debts — gov.uk — GOV.UK
• New Computerised Transit System (NCTS) — European Commission — European Commission
• The Customs Transit Procedures (EU Exit) Regulations 2018 — definitions of the offices — legislation.gov.uk — legislation.gov.uk