CDS is the current British customs declaration system, the successor to the retired CHIEF. An MRN is the reference number the system assigns to an accepted declaration and by which its status is tracked. The GMR is a separate movement reference in GVMS, and it is the GMR, not the MRN, that gets a vehicle onto the crossing.
CDS: where declarations are filed today
The Customs Declaration Service is the platform through which British import and export declarations pass. It replaced the older CHIEF system, and the migration happened in stages, imports first and exports later, so for a period both systems ran in parallel. Today CHIEF appears only in older guidance and archived paperwork, and every new declaration goes through CDS. For a Polish shipper the practical consequence is single: the British agent needs a data set in CDS format, which is stricter than the old CHIEF format and far less forgiving of shortcuts in the goods description.
MRN: the number that tells you where a declaration stands
The MRN is created the moment the system accepts a declaration and stays with it to the end. It is used to check status: whether the entry has been cleared, selected for a documentary check or routed for physical examination. It is the most important number in day-to-day operations, because it answers the question of whether a vehicle can move without a round of phone calls. Note that MRNs exist on both sides of the Channel: an EU export declaration has its own MRN, as does the transit document described in T1 and T2 transit documents.
How the MRN connects to the GMR
This is where confusion usually starts. An MRN belongs to a declaration; a GMR belongs to a movement. The carrier gathers every MRN attached to the loads on board, enters them into one movement record in GVMS and receives a GMR. At the terminal the driver presents the GMR, not a stack of MRNs. If even one MRN is wrong or its declaration has not been accepted, the GMR will not work and the vehicle is stopped before boarding. We describe the whole mechanism in the GVMS system and in what a GMR is and who prepares it.
The acronyms people mix up most
- EORI: a trader identification number for customs, one per company, described in the EORI number. It has nothing to do with a particular consignment.
- MRN: the number of a single declaration, different for every shipment.
- GMR: the number of a single border movement, covering every declaration on board.
- ENS: the entry summary declaration for safety and security, filed before arrival; it does not replace a customs entry.
What the move from CHIEF to CDS changed
For companies that were exporting to the United Kingdom before the migration, the biggest difference is the granularity of the data. CDS expects separate fields where CHIEF accepted one aggregate description, and information that could once be completed after the fact now has to be complete when the declaration is filed. That applies above all to the goods description, the tariff classification and the details of the parties. In practice a terse invoice line reading „spare parts” will not do: the agent sends it back for completion before an MRN even exists. How to word descriptions so they do not stall a movement is shown in unacceptable goods descriptions, and the cost of misclassification in the wrong HS code.
What to do when an MRN does not work
The usual causes are mundane: the declaration was submitted but not accepted, the vehicle details do not match the crossing booking, or the goods left before the entry was cleared. In practice the vehicle waits until the agent corrects the declaration. That is why on regular flows we check declaration statuses before the truck leaves the yard, not after it reaches the port. The import side is described in GB import clearance and the export side in EU export clearance step by step.
Who actually handles all this
A typical UK job involves three roles: the shipper supplies the goods data, the customs agent files the declarations and generates the MRNs, and the carrier creates the GMR and makes sure the vehicle reaches the terminal with a valid reference. We run those three threads in parallel within one job, so the situation where a declaration is ready but nobody attached it to a movement simply does not arise. The full scope is on the customs clearance page.
Sources
Not sure which number belongs to whom in your shipment? Describe the route and goods through the quote form and we will map the full document set together with who files it. The route itself is described on the transport to the United Kingdom page.
