Essential Principles checklist and declaration (MD101 and MD102)

1. Key takeaways

The Essential Principles checklist and the Essential Principles declaration form a single core group of documents in a listing file, but they are two different instruments. A general medical device uses the Essential Principles declaration on form MD101; an in vitro diagnostic medical device uses form MD102. The principles themselves are set out in technical reference file TR-004, Safety and Performance Essential Principles for Medical Devices. The difference between the two documents is not only product category. The checklist sets out, item by item, how conformity is achieved; the declaration is a formal statement that conformity exists. Their functions in the file are distinct, and an application needs both to be internally coherent.

Read together, the two documents answer three separate questions: which principles apply to this device, where the evidence for each principle sits, and whether the manufacturer formally declares conformity with the set as a whole.

• Two documents, two jobs. The checklist is an index into the technical file; the declaration is a signed statement of conformity.
• Form choice follows product type. MD101 for general medical devices, MD102 for in vitro diagnostic medical devices, decided at the start rather than at submission.
• The principles are outcome-oriented. TR-004 states the target state of safety and performance, not a list of standards that must be adopted.
• Silence is treated as non-response. A principle marked as not applicable without a reason reads as an unanswered question, not as a considered conclusion.
• Consistency between the two documents is itself a review criterion. A contradiction on any single principle casts doubt on the whole file.

2. Legal basis

The obligations are spread across a technical reference file, two declaration forms, a checklist form and the listing guidance notes. TR-004 supplies the substantive principles. The declaration forms MD101 and MD102 supply the signed statement, differentiated by device type. The checklist, in its general device and in vitro diagnostic versions, supplies the mapping between each principle and the evidence. GN-02 supplies the submission requirement that ties the package together, and MDD has published a dedicated filling guide within its at-a-glance series.

The structure of the legal basis explains a frequent misunderstanding. Neither TR-004 nor the checklist prescribes a preferred technical solution. What they prescribe is a demonstrable link between a stated principle and the evidence that the device meets it, which is why the same product can be documented in more than one acceptable way.

3. Expert insights

The principles are outcome-oriented, not standard-oriented. TR-004 defines the state of safety and performance that must be reached, not the standards that must be used. Conformity may therefore be demonstrated by a route the manufacturer chooses, but the route must be verifiable. Writing only that a given international standard is met, without explaining how that standard addresses the specific principle, is a common reason for the file being returned. The reviewer is not asking which standard was used; the reviewer is asking which principle is discharged and by what evidence.

The checklist is a signpost, not an essay. It requires the applicant to identify, principle by principle, where in which technical document and which section the supporting evidence sits. A reviewer follows the signposts, and if the indicated location does not contain the evidence, a request for further information follows. The checklist is in substance an index, and the quality of that index directly determines the efficiency of the review.

MDD published a filling guide for a reason. The at-a-glance series includes How to Fill in the Essential Principles Checklist, which signals that this document is a recurring problem area. Manufacturers should use the guide as internal training material rather than working it out from first principles. A team that has read the official guide writes a checklist that reads the way reviewers expect, which shortens the exchange of questions.

The declaration and the checklist must agree. The declaration is a formal statement about the whole; the checklist is the item-by-item detail. A conflict on any single principle raises a question about the credibility of the entire dossier, because the reviewer can no longer tell which of the two documents represents the manufacturer’s actual position.

Version drift is the quiet failure mode. TR-004 is revised from time to time, and clause numbering can move. A checklist or declaration that cites superseded numbering signals a file assembled from an old template, which invites scrutiny well beyond the point at issue.

4. Practical recommendations

• Build the index before writing the content. Create a three-column table of principle, evidence and document location against TR-004, then check whether the technical file actually contains what the table claims.
• Give a reason for every non-applicable principle. Writing not applicable without an explanation is treated as no response; state why the principle does not apply, for example because the device does not have that characteristic.
• Use the official guide for internal training. Put How to Fill in the Essential Principles Checklist on the required reading list of the project team.
• Review both documents when TR-004 changes. After an update, re-check the checklist and the declaration together so that no superseded clause number survives.
• Have a second reader trace three entries. Pick three principles at random and ask a colleague to find the evidence using only the checklist, as a reviewer would.

5. Verification checklist

• □ Form MD101 for a general device or MD102 for an in vitro diagnostic device has been selected according to product type.
• □ The checklist identifies, principle by principle, the document and section holding the evidence.
• □ Reasons have been written for every principle marked as not applicable.
• □ The declaration and the checklist are consistent with each other.
• □ The clause numbers cited match the current version of TR-004.
• □ The file has been self-checked against the official guide How to Fill in the Essential Principles Checklist.

Regulatory information verified as at 29 October 2026. The legislation, guidance and effective dates described in this article are limited to the content published by the official sources listed under legal basis on that date; where those sources are updated, the latest published version prevails.

How GRZAN can help. GRZAN provides medical device and IVD registration, quality system, authorised representative and local testing support for Hong Kong, China. Our team prepares MDACS-compliant dossiers, coordinates evidence of reference approvals and ISO 13485 certificates, and supports post-market vigilance obligations. Business enquiries: info@grzanglobal.com