Transit MRN vs Import MRN – how to tell them apart and avoid costly mistakes in the UK

The abbreviation MRN (Movement Reference Number) appears in customs documents in two entirely different contexts — and that is precisely the source of one of the most common and most costly operational errors in road transport between Poland and the United Kingdom. A Transit MRN is the number that identifies a T1/T2 transit procedure in the NCTS system, whereas an Import MRN is the number of an import declaration registered in the CDS (Customs Declaration Service). Both numbers look similar, both are routinely called "MRN" in everyday industry jargon, and both appear on documents accompanying a shipment. When a driver or operator enters the wrong MRN into GVMS when creating a GMR, the result is document rejection, an inability to clear the goods at the border, and — in the worst case — having to turn the lorry around. This article explains exactly how the two numbers differ, how to tell them apart, when to use each one, and what to do when the wrong MRN has been entered.

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What is an MRN and why are there two different types?

An MRN (Movement Reference Number) is a unique alphanumeric number assigned by the customs system at the moment an electronic declaration is accepted. It is effectively the "identity document" of every customs operation — without it, the declaration cannot be identified or tracked in the system.

The problem arises because two different customs systems operate in the UK, each generating its own MRN numbers:

1. NCTS (New Computerised Transit System) — the transit system. It generates a Transit MRN when a T1/T2 procedure is opened.
2. CDS (Customs Declaration Service) — the import/export system. It generates an Import MRN (Entry Reference Number) when an import declaration is submitted.

Historically, both systems used similar numeric formats. In industry communications, both numbers are often simply called "MRN", which leads to confusion — particularly when the same documents (CMR, driver instructions) contain both numbers without clear labelling.

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What does a Transit MRN look like and how do you recognise it?

A Transit MRN is generated by NCTS at the point of acceptance of the transit declaration (message IE028 or its Phase 5 equivalent). It is the number assigned to a specific T1/T2 movement.

Transit MRN format (NCTS Phase 5 — UK):

YY CC XXXXXXXXXXXXXXC

Where: - YY — 2-digit year of opening (e.g. 24 for 2024) - CC — 2-letter country code where the transit was opened (e.g. GB for UK, PL for Poland) - XXXXXXXXXXXXXX — 14 alphanumeric characters of the unique identifier - C — 1 check digit

Example Transit MRN: 24GB12345678901234

Where you will find the Transit MRN: - On the T1 declaration printout (transit document) - On the TAD (Transit Accompanying Document) — the document handed to the driver - In the NCTS system of the customs agent or principal - In the email/PDF from the customs agent confirming that the T1 has been opened

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What does an Import MRN look like and how do you recognise it?

An Import MRN (Entry Reference Number, ERN) is generated by the CDS system at the point of acceptance of the import declaration. In the context of road transport to the UK, it appears in two scenarios:

1. Pre-lodged declaration — a declaration submitted before the goods arrive in the UK
2. Arrived declaration — a declaration submitted after the goods have arrived

Import MRN format (CDS UK):

YYCC XXXXXXXX C

The structure is slightly different from the Transit MRN, although both contain 18 characters: - Contains an Entry number in the format characteristic of CDS - Often begins with "GB" + a customs port number + a sequence

Example Entry Reference Number (CDS): 24GB1234567890ABCD

Key visual difference: The numbers can look very similar — both are 18 characters, both contain a country code (GB). The only reliable distinguishing factor is the context of the document on which it appears: if it is a transit document (T1, TAD) — it is a Transit MRN. If it is a confirmation of an import declaration from CDS — it is an Import MRN.

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When do you use a Transit MRN — linking it to a GMR in GVMS

A Transit MRN is required in the GVMS (Goods Vehicle Movement Service) system in one specific, strictly defined scenario: when goods are entering the UK under a T1 transit procedure.

Transit MRN usage scenario in GVMS:

Goods are loaded in Poland and placed under a T1 procedure (opened in the NCTS system). The T1 movement covers transit through the EU and entry into the UK, where the goods are to be cleared for import or transferred to the next stage of transit.

When creating a GMR (Goods Movement Reference) in GVMS, the operator indicates that the goods are "under transit" and enters the Transit MRN — the T1 number from the NCTS system. GVMS verifies this number against NCTS, checking whether: - A T1 movement with that number actually exists - The movement status is active (not closed, not cancelled) - The country of opening and country of closing are consistent with the transport route

Only after a successful verification is the GMR "green" and the vehicle may enter the GVMS port.

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When do you use an Import MRN — arrived and pre-lodged declarations

An Import MRN appears in GVMS in a different scenario: when the goods are not under a T1 transit procedure but are being cleared for import on arrival in the UK.

Pre-lodged declaration (before arrival):

The importer or customs agent submits an import declaration in CDS before the vehicle arrives in the UK. The CDS system assigns an Import MRN. That number is then entered into the GMR in GVMS, allowing the port to identify the declaration when the vehicle arrives.

Arrived declaration (after arrival):

A declaration submitted after the vehicle has actually arrived in the UK. In this case the Import MRN is assigned once the goods are already there — which means the GMR must either contain a pre-lodged MRN generated earlier, or the goods are cleared by another mechanism.

Important rule: A single GMR cannot mix Transit MRN and Import MRN. A GMR for goods under transit contains a Transit MRN; a GMR for imported goods contains a pre-lodged Import MRN. If one lorry carries both transit goods and import goods, separate GMRs are required for each group, or a special GVMS configuration must be used.

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How to check which MRN you have — NCTS vs CDS format

When you are uncertain which MRN you are holding (on paper or on screen), check the source document:

Diagnostic question	Transit MRN	Import MRN
On which document does it appear?	T1 / TAD	CDS confirmation / Entry Acceptance
Which system generated it?	NCTS	CDS
Who sent it?	Customs agent (as T1 principal)	Importer / customs agent (CDS)
What country prefix?	Country where transit was opened (e.g. PL, GB, FR)	Usually GB (UK)
What accompanying document?	TAD (Transit Accompanying Document)	E2 Entry Acceptance or equivalent

Quick practical test: Call the customs agent and read out the number — ask them in which system they can find it. If NCTS — it is a Transit MRN. If CDS — it is an Import MRN.

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What happens when you enter the wrong MRN into a GMR — GVMS errors

Entering the wrong MRN into a GMR in GVMS is one of the most frequent errors in the day-to-day work of freight forwarders and drivers. The consequences vary depending on the type of error.

Scenario 1 — a Transit MRN was entered instead of an Import MRN (or vice versa):

GVMS verifies the MRN against the appropriate system (NCTS or CDS). If the number does not exist in the expected system, the GMR is rejected with an error message. A driver arriving at the port with a "red" GMR is stopped and must wait for the correction.

Scenario 2 — the correct type of MRN was entered but with a typo:

NCTS or CDS does not recognise the number — the GMR is rejected. An immediate correction by the GVMS operator is required.

Scenario 3 — a Transit MRN that is already closed was entered:

NCTS confirms the number exists, but the status is "discharged" — GVMS rejects the GMR because the transit movement has already ended.

Scenario 4 — a Transit MRN from a different movement was entered (correct format, wrong number):

NCTS confirms the number exists, but the goods data does not match. GVMS may accept the GMR, but a discrepancy will appear during the physical check — a serious customs problem.

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How to correct an MRN error in a GMR — the correction procedure

If a GMR contains the wrong MRN, the correction procedure depends on the stage at which the error was discovered.

Before the driver leaves the loading point:

The GVMS operator deletes the incorrect GMR and creates a new one with the correct MRN. No problem — the correction takes a few minutes.

The driver is en route but has not yet reached the port:

The GVMS operator can update the GMR (cancel and create a new one) up to the point of "check-in" on the carrier portal. The driver must receive the new GMR number before arriving at the port.

The driver is already at the port or in the queue:

Immediate contact with the port operator (port support desk) and the customs agent is required. At some ports an "over the counter" correction is possible — particularly if the error is obvious (a typo). At other ports the driver must leave the queue and wait for the GMR to be corrected.

The driver has passed check-in with the wrong GMR:

This is the most serious scenario. The goods are held by HMRC; a formal intervention by the customs agent is required. Waiting time: several to over ten hours. Potential costs: detention charges, parking fees, contractual penalties for late delivery.

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Pre-departure checklist — MRN verification

Use this checklist before every transport departure to the UK that involves a GMR:

• [ ] Confirm whether the goods are travelling under T1 transit (Transit MRN) or without T1 (pre-lodged Import MRN)
• [ ] Obtain the correct MRN from the customs agent — make sure you know which system it comes from
• [ ] Verify the MRN character by character — 18 characters, correct country prefix
• [ ] Check the movement status: T1 — active and not closed; Import — accepted by CDS
• [ ] Give the driver a copy of the source document (T1 TAD or CDS Entry Acceptance) together with the GMR number
• [ ] Confirm with the driver that the GMR is in the form of a QR code or 17-character number — not the MRN alone
• [ ] Set up an emergency contact: a customs agent number available around the clock in case of problems at the border