EU Declaration of Conformity

The EU declaration of conformity is an important legal document in which the manufacturer declares the conformity of their medical device. In this article you will learn:

  1. How to write a declaration of conformity
  2. The mistakes you should avoid in order to ensure there are no negative legal consequences
  3. What you should pay special attention to with the change to the EU regulations (MDR, IVDR)

A) Contents of a declaration of conformity

Annex IV of the MDR specifies what a declaration of conformity must contain:

  1. Information about the device
    1. Name of the device, registered trade name or registered trade mark
    2. Unique reference, e.g., the name, product code or catalog number, where appropriate also a photo
    3. Intended purpose of the device
    4. The device’s Basic UDI-DI
    5. The device´s risk class
  2. Information on the conformity of the device
    1. Number of devices the declaration of conformity refers to (e.g., via lot, batch or serial numbers, unit quantities)
    2. A statement from the manufacturer that the EU declaration of conformity is issued under its sole responsibility
    3. A statement that the device conforms with the requirements of the MDR “and, if applicable, with any other relevant Union legislation that provides for the issuing of an EU declaration of conformity”
    4. References to any CS used and in relation to which conformity is declared
    5. Name and identification number of the notified body involved in the conformity assessment procedure
  3. Information about the manufacturer
    1. Name and address of the manufacturer and/or its authorized representative
    2. If already issued, the SRN of the manufacturer and its authorized representative  
  4. Other
    1. Place and date of issue
    2. Name and function of the person signing the declaration
    3. Signature


If you want to write a “compliant” conformity assessment, we recommend reading ZLG EK-MED 3.9 A 4. It even contains suggested wording that you can largely adopt.

Also note that the ZLG document refers to the EU directives and that the additional requirements of the MDR/IVDR regarding the declaration of conformity also have to be met.

B) Scope of a declaration of conformity

Don’t declare conformity for an unspecified number of devices. Wording that doesn’t contain any restrictions in terms of applicability does not comply with regulatory requirements such as those of the ZLG.

The declaration of conformity must refer to:

  1. Clearly defined batch or serial numbers or software version
  2. A limited time period

Point a) comes from the requirement for “traceability”. The Blue Guide explains what the legislator means by traceability:

The declaration “must contain sufficient information to enable all products covered by it to be traced back to it.” [...] “A number identifying the product. This number does not need to be unique to each product. It could refer to a product, batch, type or a serial number.” 

Blue Guide, section 4.4 on declarations of conformity

Therefore, the law (MDR/IVDR) actually only provides for option a). Since this is impractical in medical technology and since a large number of serial/batch numbers are often produced, the ZLG has authorized option b) in Guidance Document 3.9 A4.

While the ZLG document is only written for the existing guidelines, the Johner Institute assumes that this is still applicable with the MDR. However, the requirements for the declaration of conformity content described in the ZLG document have been partially superseded by the precise requirements of the MDR.

C) Transition to the MDR

1. No more new declarations of conformity under the MDD

Article 122 of the MDR repeals the MDD (Directive 93/42) as of May 26, 2021. As a result, after May 26, 2021, no more new declarations of conformity can be signed under Directive 93/42.

Therefore, the declaration of conformity should not refer to devices with lot or serial numbers produced on or after May 26, 2021 because conformity can only be declared after production. And, from May 26, 2021, manufacturers will no longer be allowed to issue new “MDD declarations of conformity.”

2. Validity of declarations of conformity issued under the MDD

An existing declaration of conformity remains valid: According to the transition provisions in Article 123 of the MDR, you can continue to place devices that still comply with the requirements of the directive (and for which you have an annex certificate or that are classified higher by the MDR) on the market.

The declaration of conformity is considered part of the technical documentation and may no longer be modified. However, this implies that you have declared the declaration of conformity for a certain period. This period may run until May 27, 2024 at the latest.


Make sure that your declaration of conformity issued under the MDD, firstly, is not indefinite and, secondly, covers the devices placed on the market after May 26, 2021.

The validity period for “MDD declarations of conformity” may, under no circumstances, extend beyond May 26, 2024.

3. Device modifications: a special case

If you want to a non-significant modification to your device, you can make use of the transitional periods established in Article 120 of the MDR. However, the question then arises as to whether you have to issue a new declaration of conformity. This would no longer be possible under the MDD (see above).

Unfortunately, neither the MDR nor the guidance documents (e.g., the MDCG documents) provide guidance for these cases.

The problem is exacerbated by the fact that many manufacturers’ standard operating procedures explicitly require a new declaration of conformity in the event of a device modification.

The Johner Institute recommends the following when modifying devices for which conformity has been declared under the MDD:

  1. Make sure that your QM system meets the requirements of the MDR
  2. Make the changes in accordance with this QM system
  3. Document your rationale stating that
    1. the modifications are not significant (as defined in MDCG 2020-3); and
    2. the existing declaration of conformity is still valid

Further assistance from Brussels or national authorities would be desirable in this area.

 Additional information

To find out when a device modification is considered significant, you’ll have to read the article on design changes.

4. Requirements for other stakeholders

The MDR defines the actions required from a variety of stakeholders with regard to the declaration of conformity:




Responsible person

Make sure that the EU declaration of conformity has been prepared and is up to date.

Article 15


Check that an EU declaration of conformity has been issued for the device

Article 13


Check that an EU declaration of conformity has been issued for the device

Article 14

Therefore, you should be sure to do the following:

  1. Adapt your SOPs, work instructions and contracts, e.g., quality assurance agreements
  2. Inform these stakeholders of their roles/obligations
  3. Make sure of their competencies
  4. If necessary, check that the tasks, e.g., for internal audits, have been performed in full and correctly

D) Additional tips for creating a declaration of conformity

1st tip: define the responsibility for the declaration

The civil and criminal consequences of unauthorized or incorrect conformity assessment are wide ranging. Therefore, define – for example, in a standard operating procedure in your QM system – who is responsible for creating this important document and who is responsible for its release. For small and medium-sized companies, this can be the boss.

2nd tip: choose the right time to create the declaration of conformity

You cannot declare conformity until you have gone through the conformity assessment procedure for the device. Depending on the class of the medical device, this may require an annex certificate from the notified body.

However, you must have declared conformity before you affix the CE mark to your device.

3rd tip: define the device precisely

A declaration of conformity must refer to exactly one identifiable device or device type. This identifiability is generally provided by:

  • the name of the device and
  • product code
  • or another reference.

One declaration of conformity for a device class is not possible.

4th tip: keep the declaration of conformity ready

As a manufacturer, you have to maintain the conformity assessment as part of the technical documentation and be able to present it at any time upon request. A lot of manufacturers even publish them on their website.

5th tip: don’t reference any standards

Be careful not to reference “entire” standards in the declaration of conformity because, if you do, you will have to comply with the entire standard, unless you have documented elsewhere why certain parts of the standard in question are not applicable.

In addition, you would have to change the declaration of conformity every time a standard changes. According to EK Med, specifying standards is optional.


You must, however, specify the common specifications.

6th tip: download the guidance documents in good time

It is often useful to save the guidance documents on declarations of conformity that are still available on the Internet locally on your own computer. This is because government agencies and other organizations are beginning to delete them from their websites as they transition to the MDR.

E) Conclusion

The EU declaration of conformity is a short document but is very important from a regulatory point of view. Please differentiate this document from other certificates and declarations you complete for your customers. Manufacturers are under the obligation to give the declaration of conformity to importers, distributors and authorized representatives.

It is very easy to make mistakes when creating and handling this document. And that often leads to regulatory problems during audits, inspections or reviews of the technical documentation by the authorities and notified bodies. Competitors also use these errors to pester you with warnings.

The Johner Institute helps manufacturers prepare, update and review declarations of conformity. It also provides templates for the declaration of conformity, e.g., as part of its Auditgarant service. If you would like support, e.g., to avoid regulatory problems, then please contact us (contact form)right away.

Change history

  • 2021-05: The article from 2017 was completely revised
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