UK traders and logistics providers have been warned to plan around a complete shutdown of HM Revenue & Customs’ (HMRC) Customs Declaration Service (CDS) from 19:00 BST on Saturday, 26 September until 08:30 BST on Sunday, 27 September. The notice, published on the government’s service-availability page, means the UK’s primary platform for lodging import and export declarations will be offline for 13½ hours—roughly twice the length of a standard weekly maintenance window. CDS underpins almost every cross-border movement of goods into and out of Great Britain. During the outage, declarations cannot be submitted or amended, and the Goods Vehicle Movement Service (GVMS) will only recognise consignments that already carry pre-lodged declarations linked to a Goods Movement Reference (GMR). HMRC is advising hauliers moving controlled goods to be prepared to divert to inland border or port inspection facilities, while exporters are urged to secure Permission to Progress (P2P) before the system goes dark. Although the maintenance falls on a weekend evening, the timing coincides with ferry and Ro-Ro sailings departing late Saturday and arriving in the early hours of Sunday—peak periods for perishable food, retail replenishment and just-in-time automotive components. Compliance teams have therefore been scrambling to re-sequence loads, accelerate pre-lodgement or postpone discretionary traffic to avoid potential detention costs and missed delivery slots. From a business-risk perspective, the episode underlines the tight coupling between HMRC’s digital border systems and wider supply-chain reliability. Since CDS replaced the decades-old CHIEF system last year, planned outages have generally been shorter; the extended downtime suggests back-end database upgrades or major security patches are being applied. Companies that rely on automated “straight-through” customs filing may want to rehearse manual fallback procedures—such as capturing driver messages and using HMRC’s email-based ‘arrive’ function—before the window opens. In practical terms, firms should: 1) complete and submit import declarations well before 18:00 BST on 26 September; 2) print or download copies of accepted entries and GMRs; 3) brief drivers about possible inspection detours; and 4) monitor HMRC service-status pages and port-community-system alerts for confirmation that CDS is back online on Sunday morning. Failure to follow these steps could result in vehicles being refused boarding in EU ports or being held at UK Inland Border Facilities until the declaration clears.
