The UK's transition from CHIEF to the Customs Declaration Service (CDS) marked one of the most significant operational changes for UK importers and customs agents in a generation. With CHIEF now decommissioned for imports, every business submitting UK import declarations must operate through CDS — and the learning curve has been steeper than many anticipated. This guide sets out what importers need to understand about CDS in 2024 and beyond. What Is the Customs Declaration Service? CDS is HMRC's replacement for the legacy CHIEF (Customs Handling of Import and Export Freight) system, which had been in operation since the 1990s. CDS is built on the Union Customs Code (UCC) data model, meaning the structure of declarations has become more detailed, with additional data fields, revised procedures and new codes. The transition for imports was completed in 2023. Export declarations on CHIEF ran until late 2023, with CDS now the sole platform for all UK customs activity. Key Differences from CHIEF The most significant change for experienced customs agents is the shift in declaration data requirements. CDS requires more granular information at the header and item level, including: - Expanded use of Document Codes — all licences, certificates and supporting documents must be declared with the correct document code and status code. - Additional Procedure Codes (PCs) and Additional Procedure Codes (APCs) — the combination system is more complex than the legacy CPC structure. - Trader and representative identification — clearer identification of EORI numbers, declarant details and agent status is required. - Valuation methods — CDS requires explicit declaration of the valuation method used (Methods 1–6). Practical Implications for Importers For importers using in-house customs teams or working with agents, the transition to CDS has several practical implications: CDS Access and Registration: All traders need a CDS account, linked to their Government Gateway credentials. Agents acting as direct representatives require authorisation via the Trader Dress Rehearsal service or live authorisation within CDS. Duty Deferment: The deferment account process has changed. Importers must ensure their Duty Deferment Account is linked to CDS and that standing authorities are updated — the old CHIEF authorities do not automatically transfer. Immediate Payments: Where deferment is not in place, duties and VAT must be paid immediately on release. CDS uses a cash account structure which must be topped up in advance. Tariff Classification Accuracy: Because CDS applies automated checks against commodity codes more rigorously than CHIEF, classification errors are more likely to cause holds or rejections. Common CDS Errors to Avoid Based on HMRC guidance and industry experience, the most common CDS errors include: - Missing or incorrect document codes for licences, preferences or certificates - Incorrect Additional Procedure Code combinations - Failure to declare all previous documents (e.g., pre-shipment inspection certificates) - VAT number errors for postponed VAT accounting (PVA) - Incorrect country of origin vs. country of dispatch Postponed VAT Accounting and CDS Postponed VAT Accounting (PVA) remains available for UK VAT-registered importers and continues to be one of the most valuable cash flow tools for regular importers. Under PVA, import VAT is accounted for on the VAT return rather than paid at the border, providing a significant timing advantage. To use PVA correctly on CDS, the importer's EORI and VAT number must be correctly entered on the declaration, and the appropriate Additional Procedure Code must be used. Getting Support Importers and agents who encounter difficulties with CDS should access HMRC's CDS Technical Help Desk or seek guidance from a qualified customs broker. For businesses looking to review their customs agent arrangements or assess alternative providers, TCSA operates a professionally managed procurement service to assist buyers in identifying assessed customs brokers and clearing agents across the UK. Conclusion CDS represents a permanent step-change in UK customs administration. Businesses that invest in understanding the platform, review their declaration processes and work with competent agents will be best placed to manage compliance risk and operational efficiency as HMRC continues to develop the system.