What is the UK Customs Declaration Service (CDS), and how do you submit an import declaration in 2026?

By Saurabh Goyal, Founder & CEO of Phlo Systems. Published 28 June 2026.

If you import goods into the UK, every consignment needs a customs declaration, and in 2026 that declaration goes through the Customs Declaration Service (CDS). CDS replaced the old CHIEF system, and it is less forgiving: incomplete commodity codes and weak valuation data that used to slip through now get declarations rejected, which means held goods. Understanding what CDS actually wants is the difference between clearance in minutes and a shipment stuck at the frontier.

The 30-second answer:

• CDS is HMRC's platform for submitting UK import and export declarations. It replaced CHIEF.
• An import declaration tells HMRC what the goods are (commodity code), where they are from (origin), what they are worth (customs value), and the customs procedure being used.
• The most common rejection cause is an incomplete or wrong commodity code, followed by valuation and origin errors.
• You can file directly with software that connects to CDS, or use a customs broker. Either way, getting the data right before submission is what avoids delays.

What CDS is, and why it is stricter than CHIEF

CDS is the digital service through which declarations are lodged with HMRC. The migration from CHIEF was not just a new login; CDS enforces a more complete and structured data set per declaration. Fields that were optional or loosely validated before are now mandatory and checked. The practical effect for importers is that the old habit of reusing last shipment's commodity code or rounding the value no longer passes silently. CDS rejects it, and a rejected entry is a delayed shipment.

What an import declaration actually needs

Every import declaration is built around a few load-bearing data points:

• Commodity code. The full code (10 digits for UK imports) that classifies the goods and determines duty and VAT. This is where most rejections originate.
• Customs value. The value the duty and import VAT are calculated on, usually based on the price paid plus certain costs. Get the basis wrong and the figures are wrong.
• Country of origin. Determines duty rates and whether a trade agreement (FTA) preference applies.
• Customs procedure code. Tells HMRC what is happening to the goods (free circulation, warehousing, transit, and so on).
• Parties and EORI. The importer of record and their EORI number, plus consignor and consignee details.

Get those right and consistent and CDS clears the entry. Get the commodity code half-finished and it does not.

How to submit a CDS declaration

There are two routes. You can use a customs broker or forwarder who files on your behalf, which is simplest if volumes are low but adds cost and a layer of latency on every shipment. Or you can self-file using software that is connected to CDS, which gives you control, speed and lower per-declaration cost as volumes grow. The self-file route used to be the preserve of large operators; modern software has made it viable for SMEs.

Whichever route, the winning move is the same: validate the commodity code, value and origin before you submit, not after CDS bounces it back.

Self-file vs broker

	Customs broker	Self-file software
Setup	None	Connect software to CDS, hold an EORI
Cost per declaration	Higher, per entry	Lower, scales with volume
Speed	Depends on the broker queue	Immediate, on your schedule
Control & visibility	Limited	Full
Best for	Very low volumes	Regular importers, brokers, forwarders

The classification problem, and how to remove it

Because the commodity code drives both duty and rejections, classification is the highest-leverage thing to get right. Done manually, it is slow and error-prone, especially across a varied product range. This is exactly where AI classification earns its place: read the commercial invoice, propose the full commodity code with the reasoning, check duty and FTA eligibility, and pre-fill the declaration so the data that reaches CDS is complete the first time.

Frequently Asked Questions

What is CDS in UK customs?

CDS is HMRC's Customs Declaration Service, the platform through which UK import and export declarations are submitted. It replaced the older CHIEF system and enforces a more complete, validated data set per declaration.

Why do CDS declarations get rejected?

The most common cause is an incomplete or incorrect commodity code, followed by valuation and country-of-origin errors. CDS validates these fields more strictly than CHIEF did, so data that used to pass can now be rejected, which holds the shipment.

Can I submit my own CDS declarations without a broker?

Yes. With software connected to CDS and an EORI number, importers can self-file. It gives more control, faster submission and a lower per-declaration cost as volumes grow, which is why self-filing is now practical for SMEs, not just large operators.

What information do I need for a UK import declaration?

At minimum: the full commodity code, the customs value, the country of origin, the customs procedure code, and the importer's details and EORI. Getting the commodity code right is the single most important step for avoiding rejection.

How Phlo Systems helps

tradePhlo Intelligence reads your commercial invoice, classifies the goods to the full commodity code with its reasoning, checks duty and FTA eligibility, and pre-fills the declaration so the data reaching CDS is complete before submission. tradePhlo Declarations then files CDS, NCTS6 transit and NL DMS entries directly. The result is fewer rejections and faster clearance, whether you self-file or run a broker desk. See tradePhlo Intelligence.

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Related reading:

• What is landed cost, and why is my customs broker's number always wrong?
• CargoWise Alternatives for SME Customs Brokers and Freight Forwarders in 2026

Saurabh Goyal is the Founder & CEO of Phlo Systems, which builds AI customs and trade software for UK and EU importers, brokers and forwarders.