How to read a COC: every field explained
Updated 2026-08-05 · 6 min read
A Certificate of Conformity is a standardised EU form in which every entry is numbered, so the same field means the same thing on a Volkswagen document and on a Renault one. Once you know what the numbered sections cover, a COC stops looking like a wall of codes and becomes a readable technical description of your vehicle.
How is a COC laid out?
The layout follows Annex VIII of Regulation (EC) 2018/858. Page one carries the declaration itself: the manufacturer states that the vehicle identified by its VIN conforms in every respect to the type described in a named EU type approval. Everything after that is numbered technical data.
The numbering is what makes the document portable. A registration clerk in Spain looking for the CO₂ value looks for the same entry number as a clerk in Poland, regardless of the language the certificate was printed in.
- Section 0: make, type, variant, version, commercial name and VIN
- Sections 1-2: general construction data and masses
- Section 3: engine, fuel type, power and transmission
- Sections 4-8: axles, brakes, bodywork, towing and coupling data
- Sections 45-49: noise, emissions, pollutant class and CO₂
Which fields do registration offices actually use?
In practice a registration office transcribes a small subset into the national record: VIN, type-approval number, category, masses, engine power, emissions class and CO₂. Those values decide the vehicle's tax band and what may legally be towed behind it.
This is also where mismatches surface. If the CO₂ figure on the COC differs from what the seller's advert claimed, the COC wins, because it reflects the vehicle as approved and built.
What is the type-approval number and how do you read it?
The type-approval number identifies the approval the vehicle was built against, for example e1*2018/858*00123*04. The letter and digit identify the country whose authority granted it, e1 being Germany's KBA and e2 France. The middle block names the regulation, and the final block is the extension number.
A higher extension number simply means the approval has been amended since it was first issued. It is not a defect and does not affect registration.
Why do variant and version matter?
Type, variant and version describe how specific a build is: the type is broad, the variant narrows it, and the version pins down the exact combination of engine, body and equipment. Two identical-looking cars can sit on different versions and therefore carry different masses and emission values.
Because a COC is issued per VIN, it reflects your car's version, not a brochure average. That is exactly why authorities accept it instead of running their own inspection, and why an intermediary must order the document with the correct VIN rather than by model name. Coceu requests it from the manufacturer's official channel using your VIN alone.
Key takeaways
- COC fields are numbered under Annex VIII of EC 2018/858, so the same entry means the same thing in every EU language.
- Registration offices mainly transcribe VIN, type-approval number, category, masses, power, emissions class and CO₂.
- The type-approval number encodes the granting country, the regulation and an extension number.
- Type, variant and version identify your exact build, which is why a COC is always tied to one VIN.
Frequently asked questions
Why is my COC in a language I do not speak?
Manufacturers issue COCs in one or more EU languages, and because the fields are numbered, registration offices can read them regardless. A translation is rarely required.
What does e1, e2 or e13 mean on a COC?
It identifies the national authority that granted the type approval: e1 Germany, e2 France, e3 Italy, e4 the Netherlands, e13 Luxembourg, and so on.
My COC lists two CO₂ values. Which one counts?
Newer certificates show both NEDC and WLTP figures during the transition between test cycles. Registration authorities use the WLTP value for vehicles approved under that cycle.
The COC shows a different weight than the brochure. Is it wrong?
No. Brochure figures are model averages, while the COC records the masses approved for your specific version. The COC is the authoritative document.