Thank you for your post.
For Transit goods arriving inbound from the EU at a GVMS controlled port.
Whether the goods are passing through for onward travel or if the port of arrival is the Office of Destination, you must use the GVMS process to board the ferry in the EU. If the process is followed and successful, when the ship leaves the EU port, the Office of Transit formality is completed on the NCTS. On arrival in the UK, if the haulier has not been notified of a control they will continue to the Office of Destination facility at the port (or inland location if appropriate). For importers using Staged Controls, the Transit movement can be completed on presentation of the goods TAD and the EORI of the trader using the staged controls. Providing the EORI at the office of destination will be sufficient for the Transit movement to be discharged. Traders moving controlled goods will need to complete a full customs declaration or may use Simplified Customs Declaration processes if they are authorised to do so and provide the MRN at the office of destination. This process is described in the Border Operating Model (page 38). If the process is followed and goods presented correctly, there should be no reason why fallback would be required.
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