What is a Certificate of Conformity?
The Certificate of Conformity (CoC) is a vehicle-specific document issued by the manufacturer. It confirms that the vehicle conforms to its applicable European type approval, and it carries the technical information that registration and taxation rely on. Typically that includes:
- Manufacturer and vehicle identity (including the VIN)
- The European type-approval reference
- Vehicle category (for example M1 for a passenger car, N1 for a light commercial)
- Variant and version
- Engine capacity and fuel / powertrain information
- Official CO₂ emissions (WLTP and, where applicable, NEDC)
Not every vehicle has an EU CoC. Historic vehicles and vehicles that were never granted European type approval (for example some cars approved only under non-EU national rules) may have no EU CoC at all — which is exactly why the "do I need one?" question has more than one answer.
Do you need a CoC? The three Portugal routes
For the normal used light passenger-car case, it helps to think in three situations. The first two keep you on the simpler route; the third is more involved.
Case 1
You have a CoC
The standard homologation and registration route generally applies. The CoC provides the type-approval reference and technical data IMT and AT need, so the vehicle can be matched and regularised in the normal way. This is usually the smoothest path.
Case 2
No CoC, but a Portuguese national homologation record exists
The lack of a CoC does not automatically block the vehicle. If IMT's national homologation record already holds the required vehicle and tax data, presenting the CoC may not be necessary for that route. In practice this is common for models widely sold in Portugal.
Case 3
No CoC and no national homologation
A more involved homologation route may apply, and additional technical or origin documentation can be required. It is still possible to register the vehicle, but expect more steps — and, as shown below, a higher IMT homologation fee.
These describe the standard used light-passenger-car case. Treat them as the normal pattern, not a guarantee for every vehicle — confirm your specific route with IMT.
The IMT fees: €45 vs €165 (and what they are not)
The three routes map onto IMT's registration/homologation fee for a light vehicle:
| Route | IMT fee |
|---|---|
| CoC available | €45 |
| No CoC, but national homologation exists | €45 |
| No CoC and no national homologation | €165 |
Before buying: check fields K and D.2
The single most useful thing you can do before buying is to look at the foreign registration certificate and check two fields:
- K — the European type-approval / homologation number. On an EU registration certificate it typically starts with "e" and one or two digits identifying the Member State that granted approval.
- D.2 — the model, variant and version designation.
IMT uses these to look the vehicle up in its homologation records. For a European type-approved vehicle, if K and D.2 are present and filled in, the online lookup can usually proceed. If they are absent or blank, that lookup can generally only proceed when the corresponding CoC is presented — so blank K/D.2 is your signal to confirm the CoC before committing to the purchase.
Why the CoC matters for your ISV and CO₂
Portugal's vehicle tax leans on authoritative technical data. ISV is built from engine capacity and official CO₂ emissions (WLTP or NEDC, according to the vehicle's homologation), and those figures come from official documentation. The CoC is a primary source of that data, which is why it matters to a tax estimate even though it is not itself a tax document.
This does not mean you cannot estimate tax without it. A CO₂ figure from a listing or one you enter manually is a perfectly usable calculation input — it is simply not the same as confirmation. The CoC (or the official homologation record) is what confirms the figure AT will actually apply. If the CO₂ level is not stated on the CoC, a CO₂-measurement certificate from an authorised technical centre may be required for the fiscal regularisation. For how the emissions standard itself changes the figure, see WLTP vs NEDC in Portugal.
What if the seller doesn't have the CoC?
Missing paperwork is common and usually solvable. A sensible order of steps:
- Check the foreign registration certificate for fields K and D.2.
- Ask whether the seller has the original CoC, or a copy.
- Check whether the vehicle can be matched to an existing Portuguese national homologation record (this is the Case 2 route above).
- If a replacement CoC is needed, request it from the manufacturer, its national representative, or an official dealership. Availability, price and delivery time depend on the manufacturer.
- If the vehicle was never granted European type approval, expect a different homologation route rather than a CoC.
Before buying the vehicle, check:
- The VIN matches across the vehicle and its documents
- The foreign registration certificate is available
- Fields K and D.2 are filled in (where the vehicle is EU type-approved)
- A CoC is available, or you understand the alternative homologation route
- The official CO₂ / test-cycle data can be confirmed
- A purchase invoice, or a private-sale declaration, will be available
This focuses on vehicle and document readiness before purchase. The later customs declaration (DAV), inspection and registration steps are covered in the full import guide.
Special cases
UK and other non-EU vehicles
European CoC logic applies most cleanly to EU type-approved vehicles. A car from a third country may still have European type approval and a CoC — many UK cars approved before Brexit do. But a third-country origin is not automatically European type approval. Where no European type approval exists, different homologation requirements may apply. For the UK specifics, see the UK car import guide.
Vehicle category (M1, N1)
The CoC and type-approval data also establish the vehicle's official category. This matters where a vehicle looks passenger-car-like but is officially classified differently — which can change how it is taxed. See Portugal's N1 category explained for when that distinction bites.
Emissions standard (WLTP / NEDC)
The CoC and homologation data confirm the official CO₂ and the test cycle that applies to your vehicle, which in turn drives the ISV. The applicable regime follows the vehicle's homologation, not simply its registration year — the WLTP vs NEDC guide explains why that difference can move you across an ISV band.
What about the electronic CoC (eCoC)?
The EU is introducing an electronic Certificate of Conformity framework, and structured eCoC data is expected to become important for future VIN-based confirmation. For a current Portuguese import, though, you should still follow the document and homologation process published by IMT and AT.
IMT does offer an online consultation of homologation records — it can confirm whether a model is already registered nationally and issues a declaration of the corresponding homologation number. That is a homologation-record lookup, not a public "enter your VIN and download the eCoC" service. CarTaxPortugal does not rely on any Portuguese public VIN/eCoC lookup, and this page will not tell you one exists until it genuinely does.
What happens after this?
Confirming the CoC or homologation route is the document-readiness part of the job. After it come the fiscal and registration steps — the customs declaration (DAV), the inspection for attribution of a Portuguese matrícula, ISV, and the plates. The complete import guide walks through those in order, and the ISV calculator turns your vehicle's data into a cost estimate.