An MDR classification justification document is a written rationale that starts from the device's intended purpose, applies every relevant rule of Annex VIII of Regulation (EU) 2017/745, and lands on a single class — I, IIa, IIb, or III — with traceable reasoning. It belongs inside the technical documentation under Annex II, aligns with Article 51, and should be written against MDCG 2021-24. A good justification document names the intended purpose exactly, walks the rules in order, records the rule that produces the highest class as the governing rule, and states the conclusion in one sentence a Notified Body reviewer can accept or challenge on the facts.

By Tibor Zechmeister and Felix Lenhard. Last updated 10 April 2026.

TL;DR

  • Article 51 of Regulation (EU) 2017/745 requires every device to be classified according to the rules in Annex VIII, taking into account the intended purpose and inherent risks.
  • The classification justification document is the written trail of that decision. It is not optional — Annex II expects it inside the technical documentation and a Notified Body reviewer will open it on day one.
  • The document starts from the intended purpose as defined in Article 2(12) and walks every applicable rule of Annex VIII in order. Where several rules apply, the rule producing the highest class governs.
  • MDCG 2021-24 (October 2021) is the reference guidance for classification reasoning. For software, MDCG 2019-11 Rev.1 (June 2025) applies on top.
  • The most common cause of a failed first review is not a wrong conclusion but a missing trail — a rule that was not addressed, an intended purpose that drifts between sections, or a rationale that does not cite Annex VIII text.
  • The Subtract to Ship version of this document is short, literal, and rule-by-rule — no decoration, no marketing copy, no framework references that do not trace back to Annex VIII.

Why the classification justification document is the first thing a Notified Body opens

A Notified Body reviewer handed a technical documentation file does not start with the clinical evaluation or the risk file. The reviewer starts with the classification justification, because every other part of the file depends on it. Wrong classification means the wrong conformity assessment route, the wrong clinical evidence expectations, the wrong post-market surveillance obligations, and often the wrong Notified Body scope. Classification is the hinge the whole file turns on.

Article 51 of Regulation (EU) 2017/745 states that devices shall be divided into classes I, IIa, IIb and III, taking into account the intended purpose of the devices and their inherent risks, and that classification shall be carried out in accordance with Annex VIII. That is the legal obligation. The practical form of that obligation is a document the manufacturer writes and keeps in the technical documentation under Annex II — a written rationale showing how the manufacturer moved from intended purpose to class by applying the rules of Annex VIII.

The document matters beyond the audit moment. It is the reference the team returns to every time a feature is added, a claim is changed, a new user group is targeted, or a new market scenario is considered. A solid justification document makes those decisions fast. A vague one makes every product change a regulatory re-derivation from scratch.

What the MDR actually requires

Two articles and one annex govern this document.

Article 51, paragraph 1, of Regulation (EU) 2017/745 requires that devices shall be divided into classes I, IIa, IIb and III, taking into account the intended purpose of the devices and their inherent risks, and that classification shall be carried out in accordance with Annex VIII. (Regulation (EU) 2017/745, Article 51, paragraph 1.)

Article 2(12) of Regulation (EU) 2017/745 defines intended purpose as "the use for which a device is intended according to the data supplied by the manufacturer on the label, in the instructions for use or in promotional or sales materials or statements and as specified by the manufacturer in the clinical evaluation". (Regulation (EU) 2017/745, Article 2, point 12.) This exact wording is the starting point of every classification justification document — it is the definition the Notified Body reviewer will hold the rest of the document against.

Annex VIII of Regulation (EU) 2017/745 contains the classification rules — twenty-two rules organised into four chapters covering non-invasive devices, invasive devices, active devices, and special rules. Every device that falls under the MDR is classified by applying these rules. (Regulation (EU) 2017/745, Annex VIII.)

MDCG 2021-24 (October 2021) is the Medical Device Coordination Group's guidance on the classification of medical devices under the MDR. It walks every rule with worked examples and is the reference document every Notified Body reviewer will use when judging whether a classification argument holds. For software specifically, MDCG 2019-11 Rev.1 (June 2025) applies in addition and governs qualification as well as classification under Rule 11.

The structure of a classification justification document that passes

A document that passes the first review has the same six sections every time. The structure is not mandated by the MDR text — the content is. This structure is the cleanest way to make the content easy to audit.

Section 1 — Identification. Device name, model, variants, UDI-DI if assigned, manufacturer, document version, and date. This section is administrative and exists so the reviewer can tie the rationale to the specific device in the file.

Section 2 — Intended purpose. The exact intended purpose statement, quoted from the label, instructions for use, and promotional materials, consistent with the clinical evaluation. Article 2(12) of Regulation (EU) 2017/745 defines intended purpose by reference to "the data supplied by the manufacturer on the label, in the instructions for use or in promotional or sales materials or statements and as specified by the manufacturer in the clinical evaluation", and this section demonstrates that all of those sources say the same thing. Any drift between sources is a finding before the classification argument even starts.

Section 3 — Product description. A concise technical description sufficient for a reviewer to understand how the device works, what it contacts, what it powers, what it measures, and what it claims. This is the factual basis every rule application will refer back to.

Section 4 — Rule-by-rule walkthrough. Every rule in Annex VIII is addressed in order. For each rule, the document states whether the rule applies and why, and if it applies, what class the rule produces. Rules that clearly do not apply can be dispatched in a single sentence — but they must be addressed, not skipped. This is the section that distinguishes a credible document from a sloppy one.

Section 5 — Governing rule and conclusion. Where several rules apply, Annex VIII Chapter I point 3.5 of Regulation (EU) 2017/745 establishes that the rule resulting in the higher classification shall apply. The document identifies which rules produced which classes, names the rule that governs, and states the final class in one sentence.

Section 6 — References. Citations to Regulation (EU) 2017/745 (Article 51, Article 2(12), relevant Annex VIII rules), MDCG 2021-24, MDCG 2019-11 Rev.1 if software is involved, the Borderline Manual if a borderline question was considered, and the risk management file under EN ISO 14971:2019+A11:2021 if inherent risks were referenced.

The worked example — two short walkthroughs

A Class IIa wound dressing. A startup makes a non-invasive wound dressing intended to absorb exudate from superficial wounds. Section 2 states the intended purpose exactly as it appears on the label, in the IFU, and in the marketing site — all three match. Section 4 walks Annex VIII rules. Rule 1 — non-invasive devices in general contact — would land the device at Class I. Rule 2 — devices used to channel or store — does not apply. Rule 3 — non-invasive devices that modify biological or chemical composition — does not apply because the dressing does not modify composition. Rule 4 — non-invasive devices in contact with injured skin or mucous membrane — applies, and because the dressing is intended for mechanical barrier or absorption of exudates on wounds breaching the dermis, Rule 4 produces Class IIa. Section 5 records Rule 4 as the governing rule and the final class as IIa. The whole document is perhaps four pages. It is enough.

A Class IIa decision-support SaMD. A startup builds software that analyses ECG recordings and flags suspected arrhythmias for clinician review. Section 2 quotes the intended purpose exactly and consistently across label, IFU, website, and clinical evaluation. Section 4 walks Annex VIII rules, reaches Rule 11, and applies it with MDCG 2019-11 Rev.1 Rule 11 worked examples cited directly. The software provides information used to take decisions with a diagnostic purpose — at least Class IIa. The decisions do not by themselves cause death or irreversible deterioration, nor serious deterioration of health or a surgical intervention, so Rule 11 lands at IIa rather than IIb or III. Section 5 records Rule 11 as the governing rule and the final class as IIa. The document references MDCG 2019-11 Rev.1 directly and walks the specific examples that most resemble the device.

Both documents share the same spine: intended purpose quoted exactly, rules walked in order, governing rule named, conclusion stated.

The template — what to reuse, what to tailor

The reusable parts of a classification justification document are the structure, the references, and the Annex VIII rule text. Every project uses the same six sections, the same citation format, and the same full-text copies of the rules being applied. Copying rule text directly into the document is good practice — it lets the reviewer read the rationale against the rule without leaving the document.

The tailored parts are the intended purpose, the product description, and the specific reasoning for why each rule applies or does not. These cannot be templated because they are the substance. A classification justification document that reuses language from another device is a classification justification document that is about to invent facts about the current device — this is where classification errors originate.

A practical playbook for writing the document from scratch in one sitting:

  1. Draft the intended purpose statement and verify the label, IFU, website, and clinical evaluation all say the same thing. If they do not, fix them before continuing.
  2. Write the product description in plain language — what it touches, powers, measures, claims.
  3. Open Annex VIII of Regulation (EU) 2017/745 and MDCG 2021-24 side by side. For SaMD, open MDCG 2019-11 Rev.1 as well.
  4. Walk every rule in order. For each rule write one line if it does not apply, one paragraph if it does. Name the class each applicable rule produces.
  5. Identify the governing rule under Annex VIII Chapter I point 3.5 and state the final class in one sentence.
  6. Assemble references. Versioning and date-stamp the document.
  7. Route it through the internal review that the QMS requires before it enters the technical documentation file.

The Subtract to Ship version of this document is the shortest document that still contains every required element. Decoration is cost; only the rule-by-rule walk and the intended purpose are load-bearing.

Reality Check — Where does your classification justification document stand?

  1. Is the intended purpose quoted verbatim from the label, IFU, marketing materials, and clinical evaluation, and do all four sources say the same thing?
  2. Is every rule in Annex VIII addressed in order, with a sentence explaining why it does or does not apply — not just the rules that turned out to matter?
  3. If multiple rules applied, is the governing rule named explicitly under Annex VIII Chapter I point 3.5 and is the higher class recorded as the conclusion?
  4. Is MDCG 2021-24 cited and, for any software involved, is MDCG 2019-11 Rev.1 cited with the specific worked examples used?
  5. Does the document reference the risk management file under EN ISO 14971:2019+A11:2021 where inherent risks informed a rule application?
  6. Is the document versioned, dated, signed off under the QMS, and sitting inside the technical documentation under Annex II?
  7. Could a Notified Body reviewer read only this document and understand the classification argument without asking a single clarifying question?

Any question without a clear yes is a gap worth closing before the file leaves the manufacturer.

Frequently Asked Questions

Is a classification justification document legally required under the MDR? Article 51 of Regulation (EU) 2017/745 requires every device to be classified according to Annex VIII taking into account intended purpose and inherent risks, and Annex II expects the classification and its rationale to be part of the technical documentation. The document is the practical form of that requirement. A technical documentation file without a written classification rationale is an incomplete file, and a Notified Body will treat it as one.

How long should the document be? As long as it needs to be and no longer. For a simple Class I non-invasive device the document may fit on two pages. For a Class IIb implantable with several rules in contention it may run ten or more. Length is not a quality signal — coverage is. Every applicable rule must be addressed explicitly; everything else is decoration.

What if more than one rule applies? Annex VIII Chapter I point 3.5 of Regulation (EU) 2017/745 establishes that where several rules apply, the rule resulting in the higher classification governs. The document names every applicable rule, the class each produces, and the governing rule explicitly. This is one of the most commonly missed steps in weak documents.

Which guidance document should I use? MDCG 2021-24 (October 2021) is the primary classification guidance for medical devices under the MDR. For software, MDCG 2019-11 Rev.1 (June 2025) applies on top and governs qualification and classification under Rule 11. For borderline questions — is this a medical device at all, or is it a cosmetic or biocide — the Borderline Manual v4 (September 2025) is the reference.

Who writes it and who signs it off? The regulatory lead typically drafts it, with input from product, engineering, and clinical. It is reviewed and signed off under the QMS before entering the technical documentation. In a startup without a full-time regulatory role, the founder or the fractional regulatory resource writes it — but it must be reviewed by someone who understands Annex VIII well enough to catch a missing rule or a drifting intended purpose.

Can the document change after the device is on the market? Yes, and it must, whenever the intended purpose, indications, user population, device design, or claims change in a way that could affect classification. A change to the classification rationale is a change to the technical documentation and follows the same change-control process under the QMS as any other technical documentation change.

Sources

  1. Regulation (EU) 2017/745 of the European Parliament and of the Council of 5 April 2017 on medical devices, Article 2(1) (definition of medical device), Article 2(12) (definition of intended purpose), Article 51 (classification), Annex II (technical documentation), Annex VIII (classification rules). Official Journal L 117, 5.5.2017.
  2. MDCG 2021-24 — Guidance on classification of medical devices, Medical Device Coordination Group, October 2021.
  3. MDCG 2019-11 — Guidance on Qualification and Classification of Software in Regulation (EU) 2017/745 — MDR and Regulation (EU) 2017/746 — IVDR. First published October 2019; Revision 1, June 2025.
  4. EN ISO 14971:2019+A11:2021 — Medical devices — Application of risk management to medical devices.

This post is part of the Device Classification & Conformity Assessment series in the Subtract to Ship: MDR blog. Authored by Felix Lenhard and Tibor Zechmeister. The MDR is the North Star for every claim here — MDCG 2021-24 and MDCG 2019-11 Rev.1 are interpretive guidance the Notified Body will use to judge whether the classification rationale holds. For startup-specific regulatory support on classification justification and technical documentation, Zechmeister Strategic Solutions is where this work is done in practice.