Customs Declaration Service (CDS): A Practical Transition Checklist for eCommerce

The move from CHIEF to the UK Customs Declaration Service (CDS) in 2024 has introduced a new level of complexity for eCommerce retailers shipping cross-border. With greater emphasis on data accuracy, compliance and digital interoperability, Operations and Compliance teams are under increasing pressure to map, structure and submit declarations correctly.

While CHIEF was familiar and relatively static, CDS brings new data fields, new codes and new processes. The transition is essential but challenging and many businesses still risk delays, rejected declarations and cost exposure if their data is not fully aligned to CDS requirements.

To help simplify the change, this practical checklist breaks down what has changed, what data is now required, how to test declarations and how to integrate CDS-ready data into everyday operations.

CHIEF → CDS: What Has Changed?

The shift from CHIEF to CDS represents more than a system upgrade. It is a wholesale modernisation of how UK customs handles data. CDS requires richer and more granular information on every shipment, meaning less room for error and far greater scrutiny on tariff codes, values and documentation.

Key changes include:

  • A move from CHIEF’s limited dataset to a fully structured, multi-layered data model
  • New mandatory fields, particularly around valuation, tax type and duty method
  • More detailed HS codes and commodity information
  • A new digital finance model, including postponed VAT accounting and guarantees
  • Revised declaration categories, including the use of Additional Information (AI) statements

For retailers shipping internationally at scale, this means product data, checkout information, carrier labels and customs documentation all need consistency across multiple systems. In our 2025 Basket Abandonment Report, we highlight how errors or uncertainty around duties and taxes can damage customer confidence at checkout. CDS raises the stakes by tightening the accuracy required upstream in the process.

Must-Have CDS Fields for Accurate Declarations:

CDS requires several critical data points that were not mandatory in CHIEF or are now expected in a more detailed format. Ops and Compliance teams should prioritise the following:

  • Correct commodity codes (10-digit HS codes for exports, 8-digit for imports)
  • Clear product descriptions written in plain commercial language
  • Valuation details, including Incoterms, adjustments, discounts and freight charges
  • Country of origin, with full provenance data where applicable
  • Item-level weights and values, not just shipment totals
  • Preference codes, where trade agreements apply
  • VAT and duty calculation details, including method of payment

A helpful baseline for current requirements can be found on GOV.UK

Retailers who sell across multiple marketplaces should check that product listings, Product Information Management (PIM) data and carrier label data contain the same information — discrepancies are a primary cause of CDS rejections.

Testing Declarations Before Go-Live

Testing is one of the most overlooked parts of the CDS transition. Carriers, brokers and customs intermediaries all have different testing environments and eCommerce retailers need to validate that:

  • All mandatory CDS data fields are mapped correctly
  • Declarations generate the correct tax and duty calculations
  • Error codes are understood, logged and remapped
  • Fallback processes exist during Peak trading periods

For many retailers, the barrier is not the CDS system itself but the number of internal systems feeding data into it. ERP, OMS, WMS, checkout, marketplace listings, product databases and carrier integrations must all speak the same data language.

GFS provides structured onboarding and testing workflows across all key carriers, helping retailers identify gaps early and reduce risk during transition.

Integrating CDS Data Into Your Operations

Once declarations are mapped and tested, the next challenge is operational integration. This means embedding CDS-ready data into daily processes to remove manual intervention and maintain compliance at scale.

Retailers should focus on:

  • Centralising product and customs data in a single, authoritative source
  • Automating data transfer between checkout, label generation and customs filing
  • Monitoring error messages and exception reports daily
  • Ensuring multi-carrier compatibility, as not all carriers handle CDS fields in the same way
  • Auditing data regularly, especially when products change or new markets open

For retailers using multi-carrier services, delivery platforms like GFS’ Managed Multi-Carrier Delivery makes CDS integration significantly easier by unifying customs data, delivery labels and carrier rules within one workflow.

Teams managing warehouse processes can also benefit from GFS Operations, which improves accuracy at pick, pack and despatch, ensuring the right data follows the right parcel.

For businesses looking to expand their international reach, GFS International Delivery Services provides carrier-agnostic cross-border solutions with built-in compliance support.

How GFS Helps Retailers Navigate CDS with Confidence

The transition to the Customs Declaration Service is unavoidable, but it does not need to disrupt operations. With more complex data structures, stricter validation and increased compliance pressure, retailers need a partner that is knowledgeable, trusted, pro-active and empowering – all core attributes of the GFS brand. 

GFS integrates delivery, customs data and multi-carrier technology into one seamless workflow. Our experts support retailers through data mapping, testing and stabilising CDS processes; helping them avoid delays, reduce errors and protect customer experience at checkout. With unmatched customer service and deep operational knowledge, GFS ensures retailers stay compliant and competitive as the CDS landscape evolves.