Declaration of Conformity and CE Marking: The Final Step and What It Commits You To

What the CE mark actually represents

The CE mark on a medical device is a manufacturer's declaration that the device meets all applicable EU regulatory requirements. For medical devices, that primarily means MDR (or IVDR for in vitro diagnostics), but it can also involve other directives — the Radio Equipment Directive for wireless devices, for example. The CE mark is not a quality seal, not a safety guarantee, and not a government approval. It is a declaration, made by the manufacturer, that the device conforms.

This is important because it means the legal responsibility sits with the manufacturer. When you affix the CE mark, you are stating that you have completed the required conformity assessment, that your device meets the General Safety and Performance Requirements of Annex I, and that you have the documentation to support that claim. If a market surveillance authority comes to check — or if a serious incident prompts an investigation — that documentation needs to exist and needs to hold up.

What has to be in the Declaration of Conformity

Article 19 of MDR sets out what the Declaration of Conformity must contain. The requirements are specific:

• Name and address of the manufacturer (and Authorised Representative if applicable)
• A statement that the DoC is issued under the sole responsibility of the manufacturer
• Device identification: name, trade name, product or catalogue number, lot or batch number if applicable, intended purpose
• A statement that the device conforms to MDR, and any other applicable EU legislation
• References to relevant harmonised standards or common specifications applied
• The Notified Body name and identification number (if applicable), the certificate number, and the date of issue and expiry
• Name and date, with the signature of the authorised person responsible

If your device is Class I self-certified, you are the sole signatory. If a Notified Body was involved, the certificate information must appear. The DoC must be updated every time relevant changes are made to the device.

The DoC is a living document, not a one-time output

One of the more common misconceptions is that the Declaration of Conformity is produced once, at the end of the conformity assessment process, and then filed. It is not. The DoC must remain current. If your device changes — in design, materials, labelling, intended purpose, or manufacturing process — and that change is significant enough to affect conformity, the DoC needs to be reviewed and potentially reissued.

What counts as a significant change? This is a judgement call that should be documented in your change management process. MDR does not define a bright line, but the practical test is: would this change affect the device's conformity with the GSPRs, or would it fall outside the scope of your existing Notified Body certificate? If yes, you need to assess whether the change requires Notified Body notification, re-review, or a new certificate. Getting this wrong — making a change that required Notified Body involvement and not involving them — is a serious non-conformity.

Affixing the CE mark: the rules

The CE mark must appear on the device or its sterile packaging, and on the instructions for use. For devices where this is not practical due to size, the mark must appear on the packaging and in the IFU. The mark must be at least 5mm tall if size permits, and must be affixed visibly, legibly, and indelibly.

The Notified Body identification number follows the CE mark immediately, whenever a Notified Body was involved in the conformity assessment. The format is the four-digit NB number placed directly after the CE mark. If you had a Notified Body involved and the number is not on the device, that is a non-conformity.

You cannot CE mark a device until the conformity assessment is complete and the DoC is signed. Affixing the mark before you have finished the assessment — even if you believe you will pass — is a regulatory violation.

What the mark commits you to after placing it

Once a device is CE marked and on the market, you have ongoing obligations that the mark represents. You are committed to maintaining the QMS, keeping technical documentation current, running post-market surveillance, reporting serious incidents, and updating your DoC and re-engaging your Notified Body if significant changes arise. The CE mark is not a historical statement about what the device was when it was certified — it is a continuing claim that the device meets requirements now.

Market surveillance authorities in EU member states conduct checks on CE marked devices. They can request your technical documentation, your DoC, and your post-market surveillance records. If they find a gap between what the mark claims and what the documentation shows, the consequences range from corrective action requests to market withdrawal. The practical implication is that every piece of documentation behind the CE mark needs to be maintained in a state where you could respond to a surveillance request within the required timeframes — typically 7–30 days depending on the authority and urgency.