The UK's Customs Declaration Service (CDS) has replaced CHIEF (Customs Handling of Import and Export Freight) as HMRC's primary customs declaration platform. The transition represents the most significant change to UK customs IT infrastructure in decades — with implications for importers, exporters and the customs agents and brokers who lodge declarations on their behalf. WHAT IS CDS? CDS is HMRC's modernised customs declaration platform, designed to meet the requirements of the Union Customs Code (which the UK retained elements of post-Brexit) and to support expanded data fields and declaration types required under modern international customs standards. CHIEF VS CDS: KEY DIFFERENCES - CDS supports a significantly larger number of data fields per declaration - Declaration procedures and authorisation codes have changed - Additional supporting document references are required in many scenarios - The deferment account approval process has updated - CDS introduces Declaration Unique Consignment Reference (DUCR) structures - Additional customs procedure codes apply to common import scenarios IMPACT ON IMPORTERS For businesses that lodge their own declarations, CDS requires system updates, staff retraining and, in many cases, reconfiguration of existing customs software. For businesses that use customs brokers or agents, the primary risk is whether their appointed agent is fully CDS-compliant and operationally stable on the new platform. CHECKING YOUR CUSTOMS BROKER'S CDS COMPLIANCE Key questions for your current or prospective customs agent: - Have all staff been trained on CDS declaration procedures? - Is your declaration software fully CDS-certified? - Have you experienced any disruption during the CHIEF-to-CDS transition? - Are you submitting declarations via direct trader input or intermediary software? - Can you evidence your CDS throughput volumes? CDS AND PROCUREMENT CDS compliance is now a baseline requirement in customs brokerage procurement. TCSA includes CDS operational status as a standard capability assessment criterion when sourcing customs brokers for buyers through the TCSA independent procurement service.