UK Continental Shelf Movements: The Complete Customs Framework

The UK Continental Shelf is the area of regional waters outside UK territorial waters, extending across parts of the North Sea, the North Atlantic, the Irish Sea, and the English Channel, where the UK holds mineral rights under an Order made pursuant to the Continental Shelf Act 1964. An installation, for these purposes, means an artificial island, a fixed or floating installation, or any other structure, which in practice covers oil and gas rigs and platforms, wind turbines, and tidal barrages or stream generators. Goods moving between this area and Great Britain are treated as an export or an import, and energy produced on the UKCS is itself treated as an import.

This last point catches operators out more often than it should: it is not only physical goods crossing this boundary that trigger a customs obligation. The boundary itself, and what counts as crossing it, is worth understanding precisely before looking at how a declaration is actually made.

Where the Customs Boundary Actually Sits

UK territorial waters extend 12 nautical miles from the coastline, and this area sits inside the UK’s customs territory. Movements between Great Britain and installations within these 12 miles are not treated as exports or imports at all. Goods brought from outside the UK for use within territorial waters must still be declared to UK free circulation before use, but once in free circulation, they move freely within the mainland and territorial waters without a further customs event.

Beyond the 12-mile limit, on the UKCS proper, every movement is a customs event. A reel of cable imported from the United States to connect a windfarm sitting within 12 miles of the coast to an onshore transmission operator, for instance, must be declared as an import precisely because it will be used within UK territory, even though the installation itself might reasonably be assumed to sit “offshore” in a general sense. The precise location relative to the 12-mile line, not the general offshore character of the installation, is what determines the customs treatment.

Northern Ireland Movements Are Governed Differently

Movements between Northern Ireland and the UKCS do not follow the Great Britain framework at all. They fall under the Union Customs Code and are treated as imports or exports under that regime. Where goods are destined for sale to, or end use by, a consumer located in the UK, including within the 12-mile limit, they may be eligible to move “not at risk” under the UK Internal Market Scheme and benefit from Windsor Framework arrangements. Where goods move from Great Britain, through Northern Ireland, to a destination outside the UK, including the UKCS, they are not eligible under that scheme, a full customs declaration is required, and the applicable EU duty rate may be payable, subject to any waivers or reliefs.

Critically, the UKCS declaration by conduct process, the simplified route most GB-based operators rely on, is not available at all for movements between Northern Ireland and the UKCS. An operator with both GB and NI-based logistics needs to treat these as genuinely separate customs regimes, not a single process with minor regional variation.

The Three Ways to Declare a Movement

For movements between Great Britain and the UKCS, a declaration can be made in one of three ways: a full customs declaration, a simplified declaration process (either the Simplified Declaration Procedure or Entry in Declarant’s Records), or the UKCS declaration by conduct process. Goods that are not eligible for the routes set out in the relevant regulations, or that are moving between the UKCS and Northern Ireland, must use a full or simplified declaration through the Customs Declaration Service instead.

Where goods are held in a customs special procedure immediately before export, other than Authorised Use, or are intended to enter a special procedure on import, a full or simplified declaration is required regardless of whether the goods would otherwise qualify for the simplified route.

Full declarations carry their own timing requirements that are easy to overlook precisely because the declaration by conduct process feels comparatively informal. Where a temporary storage declaration has been made, the full import declaration is due within 90 days of the goods being presented to customs. Where goods arrive at a location without temporary storage facilities, the import declaration is due at the time of presentation, which must occur within three hours of arrival, or within one hour of the location’s next opening if it is closed on arrival.

Declaration by Conduct: Eligibility and Mechanics

The declaration by conduct process allows eligible low-risk goods to be declared simply through the physical act of loading or unloading them, combined with submitting information to HMRC through the UK Continental Shelf imports and exports form, the National Maritime Single Window service, or the General Aviation Report form.

For goods returning to Great Britain, eligibility requires the goods not be prohibited, restricted, or excise goods, and additionally requires that they have previously been in UK free circulation and meet Returned Goods Relief criteria, were previously declared to the Authorised Use procedure and properly discharged, or are human or domestic waste intended for disposal rather than resale or recycling. For goods moving to the UKCS, eligibility requires the goods to already be in UK free circulation or entered into Authorised Use, and again excludes prohibited, restricted, and excise goods.

The submission must be made no later than one hour before the goods arrive or depart. Once submitted, a declaration cannot be cancelled, only recorded internally as cancelled if the movement itself does not proceed. Minor changes, a change in timing, a change in the number of packages, or something removed from the cargo, are recorded internally rather than resubmitted. Anything beyond this, additional goods, or a change of customs procedure, requires a new submission referencing the original’s unique reference number.

Goods descriptions for this process need only be in plain language sufficient to identify, classify, and allow examination of the goods, drilling equipment, oil well equipment, ambient food items, or household goods are all acceptable levels of description, a notably lighter requirement than the precision demanded on a full CDS declaration.

Personal Effects, Hand Tools, and Ships’ Stores Sit Outside This Framework Entirely

Not everything moving to or from an installation requires any declaration at all. Personal effects, clothing, toiletries, personal electronics, prescription medication, and hand tools an employee owns or is personally issued, spanners, hand drills, painting equipment, can simply be carried by the person using them onto the vessel or aircraft. No CDS declaration, g-form, or FAL/GAR submission is required. Where personal items are instead moved as freight, separately from their owner, for example on a support vessel while the owner travels by air, they do need to be declared, though they are highly likely to qualify for both Returned Goods Relief and the declaration by conduct process.

Ships’ and aircraft stores, goods intended for use on board during the journey itself rather than at the installation, sit under a separate regime again. Fuel, spare parts integral to running the vessel, retail goods sold to crew or passengers, and food and drink for consumption on board are all declared “by conduct” in the sense that the act of loading them satisfies the requirement, with no electronic declaration needed at all, provided the vessel remains beyond the 12-mile limit. The distinction that catches operators out is between stores and cargo intended for the installation itself: where more of a good is exported as apparent cargo than an installation actually needs, and the surplus returns to shore, that surplus must be declared as a re-import, exactly as any other returning cargo would be.

Samples intended for testing, analysis, or examination may separately qualify for relief from import duties under the general goods-for-testing relief, though that relief must be claimed through a full CDS declaration, not through declaration by conduct. Unused sample kits, or parts of kits, being returned unchanged can use the declaration by conduct route instead, provided they independently meet its ordinary eligibility criteria.

What Happens When Something Goes Wrong

A voluntary disclosure is required wherever a movement has not been declared in any form, or where declaration by conduct was used in error, for example where controlled goods that were also subject to customs warehousing were exported using declaration by conduct instead of obtaining proper permission to proceed, or where goods imported under declaration by conduct turn out not to be fully eligible for Returned Goods Relief after all.

Where the error resulted in an underpayment of duty or VAT, this is corrected through a voluntary clearance amendment. Where it resulted in an overpayment, a repayment can be claimed through HMRC’s standard overpayment process. Where no export declaration was made at all at the time of export, a retrospective declaration can still be submitted, though HMRC needs to be contacted directly to ensure it is properly cleared against the movement it relates to.

This is worth treating as a distinct compliance obligation in its own right, not merely a footnote to the declaration process. An operator using declaration by conduct at volume, precisely because the process feels lightweight, is at real risk of the eligibility question being checked less rigorously than a full declaration would receive, which is exactly the condition under which a voluntary disclosure obligation arises without anyone noticing until much later.

The Underlying Record-Keeping Obligation Does Not Change

Whichever declaration route is used, the underlying obligation to keep adequate records is unchanged, and this is where the simplification in process most often creates a false sense of reduced obligation. Records must identify the eligible goods and demonstrate that eligibility, support any Returned Goods Relief or Authorised Use discharge claim, evidence the goods’ origin and value, and include commodity codes and a packing list or manifest. Where the goods are not owned by the party making the declaration, further records are needed showing clear instructions from the customer, the relevant contracts, and the goods’ final destination. All of this must be retained for a minimum of four years.

If your organisation moves goods to or from the UK Continental Shelf and would like a second opinion on your current declaration approach across these different movement types, feel free to reach out directly.