MDR Classification: The 22 Annex VIII Rules Explained

MDR classification explained: the 22 Annex VIII rules, classes I, IIa, IIb and III, the implementing rules and MDCG 2021-24 rev.1 of April 2026.

Each rule starts from the intended purpose and gives a default class with exceptions, and where several rules apply to one device, MDR Annex VIII Section 3.5 gives the higher class.

Manufacturers classify a device before they compile its technical documentation, notified bodies check that classification, and a competent authority decides when the two disagree. Below follow the four classes, all 22 rules, the implementing rules, the order of classification, MDCG 2021-24 rev.1 of April 2026, reclassification, disputes and the changes pending as of 6 November 2026.

What Is MDR Classification?

MDR classification is the risk-based sorting of medical devices into four classes, I, IIa, IIb and III, which MDR Article 51(1) ties to the classification rules of Annex VIII of Regulation (EU) 2017/745.

The MDR is a regulation: it entered into force on 25 May 2017 and has applied since 26 May 2021 (MDR Article 123(1) and (2), the date of application as amended by Regulation (EU) 2020/561). It is directly applicable in every member state without national transposition, and classification is one of the first duties in the framework of the EU MDR and IVDR.

Classification follows the intended purpose, which MDR Article 2(12) defines by the data the manufacturer supplies on the label, in the instructions for use, in promotional or sales materials or statements and in the clinical evaluation. In vitro diagnostic devices are classified under their own system in the IVDR.

The Legal Basis: MDR Article 51

MDR Article 51(1) divides devices into classes I, IIa, IIb and III and sends the classification to Annex VIII, and Article 51(2) refers disputes to a competent authority. Article 51(3) to (5) give the Commission implementing powers: on the application of Annex VIII (point (a) of paragraph 3), on reclassification (point (b)), on its own initiative (paragraph 4) and on divergent interpretation (paragraph 5), each adopted under the examination procedure of MDR Article 114(3). The full wording sits in the consolidated MDR on EUR-Lex.

MDR Annex VIII is unchanged since 2017; changes to the rules are only proposed. Article 51 and Annex VIII are part of the EU MDR (Regulation (EU) 2017/745).

How Annex VIII Is Built

MDR Annex VIII has three chapters: Chapter I defines the terms used by the rules, Chapter II sets the implementing rules in Sections 3.1 to 3.7, and Chapter III holds the 22 classification rules in Sections 4 to 7. The implementing rules of Chapter II apply first, so they frame the reading of every rule in Chapter III.

Chapter III groups the rules by the type of device. Section 4 covers non-invasive devices (Rules 1 to 4), Section 5 invasive devices (Rules 5 to 8), Section 6 active devices (Rules 9 to 13) and Section 7 the special rules (Rules 14 to 22).

Classes I, IIa, IIb and III at a Glance

The MDR has four classes, from class I (lowest risk) to class III (highest risk), and class I has three sub-types, Is (sterile), Im (measuring function) and Ir (reusable surgical instruments), for which a notified body checks only those aspects (MDR Article 52(7)(a) to (c)). There is no class IV under the MDR, and the legal names are class IIa and class IIb, not "2a" or "2b".

The class decides the conformity assessment route under MDR Article 52 and the cycle of the periodic safety update report (PSUR) under MDR Article 86(1); class I devices have a post-market surveillance report under MDR Article 85 instead. The route per class is set out under MDR conformity assessment.

The table compares the four classes.

Class	Typical rules leading to it	Notified body	PSUR (MDR Article 86(1))	Route article
class I medical devices under the MDR	Rules 1, 2, 4, 5, 6 (reusable surgical instruments), 10 (visible-light illumination), 11 (other software), 13	None; for Is, Im and Ir limited to sterile conditions, metrology or reuse aspects (MDR Article 52(7)(a) to (c))	None; post-market surveillance report under MDR Article 85	MDR Article 52(7)
class IIa medical devices	Rules 2, 3, 4, 5, 6, 7, 8 (teeth), 9, 10, 11, 12, 16, 17, 19 (negligible exposure), 20, 21	Yes	When necessary and at least every two years	MDR Article 52(6)
class IIb medical devices	Rules 2 (blood bags), 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 15, 16, 19, 20, 21	Yes	At least annually	MDR Article 52(4)
class III medical devices	Rules 3 (IVF media), 6, 7, 8 (listed indents), 9 (active implantable control), 11, 14, 15, 18, 19, 21, 22	Yes	At least annually	MDR Article 52(3)

Indicative overview; each class page lists the rules, examples and route in full.

The 22 Classification Rules in One Table

MDR Annex VIII Chapter III sets 22 rules: non-invasive devices under Rules 1 to 4, invasive devices under Rules 5 to 8, active devices under Rules 9 to 13 and special rules under Rules 14 to 22, and each rule gives a default class with exceptions. The 22 rules have applied since 26 May 2021 and replaced the 18 rules of the repealed Directive 93/42/EEC (MDD). The table gives each rule with its Annex VIII section, the devices it covers and the classes it leads to.

Rule	Annex VIII section	Covers	Resulting class
1	4.1	Non-invasive devices (fall-back)	I
2	4.2	Non-invasive devices channelling or storing blood, body liquids, cells, tissues, liquids or gases for infusion or administration	I; IIa if connectable to a class IIa, IIb or III active device or used for blood, body liquids, organs, cells or tissues; blood bags IIb
3	4.3	Non-invasive devices modifying the biological or chemical composition of blood, tissues or body liquids	IIb; IIa for filtration, centrifugation or exchange of gas or heat; III for substances in direct in vitro contact with cells, tissues, organs or embryos before implantation or administration (IVF media)
4	4.4	Non-invasive devices in contact with injured skin or mucous membrane	I for mechanical barrier, compression or absorption of exudates; IIa for the micro-environment and other cases; IIb for wounds breaching the dermis that heal only by secondary intent
5	5.1	Devices invasive through a body orifice, not surgically invasive	I transient; IIa short term (I in the oral cavity, ear canal or nasal cavity); IIb long term (IIa there if not absorbed); IIa if connected to a class IIa, IIb or III active device
6	5.2	Surgically invasive devices, transient use	IIa; I for reusable surgical instruments; III for the heart, central circulatory or central nervous system; IIb for ionising radiation, a biological effect, absorption or hazardous delivery of medicinal products
7	5.3	Surgically invasive devices, short-term use	IIa; III for the heart, central circulatory or central nervous system, a biological effect or absorption; IIb for ionising radiation, chemical change or administering medicinal products
8	5.4	Implantable and long-term surgically invasive devices	IIb; IIa in the teeth; III for the listed indents (heart, central circulatory or central nervous system, biological effect or absorption, chemical change, medicinal products, active implantable devices or their accessories, breast implants, surgical meshes, total or partial joint replacements, spinal disc replacements and implants contacting the spinal column)
9	6.1	Active therapeutic devices administering or exchanging energy	IIa; IIb for potentially hazardous energy, control of class IIb active therapeutic devices or therapeutic ionising radiation; III for controlling, monitoring or directly influencing active implantable devices
10	6.2	Active devices for diagnosis and monitoring	IIa; I for illumination in the visible spectrum; IIb for vital parameters where variations could result in immediate danger, and for ionising radiation in diagnostic and interventional radiology
11	6.3	Software (Rule 11 for software)	IIa for information used for diagnostic or therapeutic decisions; III where such decisions may cause death or irreversible deterioration; IIb where they may cause serious deterioration or surgical intervention; IIa for monitoring physiological processes, IIb for vital parameters with immediate danger; I for all other software
12	6.4	Active devices administering or removing medicinal products, body liquids or other substances	IIa; IIb if potentially hazardous
13	6.5	All other active devices	I
14	7.1	Devices incorporating a substance that would be a medicinal product, including a human blood or plasma derivative, with ancillary action (drug-device combinations with an ancillary medicinal substance)	III
15	7.2	Devices for contraception or prevention of sexually transmitted diseases	IIb; III if implantable or long-term invasive
16	7.3	Devices for disinfecting, cleaning, rinsing or hydrating contact lenses, and for disinfecting or sterilising devices	IIb for contact lenses; IIa for disinfecting or sterilising devices; IIb for disinfecting solutions and washer-disinfectors for invasive devices as the end point of processing
17	7.4	Devices recording diagnostic images generated by X-ray radiation	IIa
18	7.5	Devices made with non-viable tissues or cells of human or animal origin, or their derivatives	III, unless of animal origin and in contact with intact skin only
19	7.6	Devices incorporating or consisting of nanomaterial	III for high or medium internal exposure; IIb for low; IIa for negligible
20	7.7	Devices invasive through a body orifice administering medicinal products by inhalation	IIa; IIb if the mode of action essentially affects efficacy and safety, or for life-threatening conditions
21	7.8	Substances introduced via a body orifice or applied to the skin and absorbed or locally dispersed	III if systemically absorbed, or acting in the stomach or lower gastrointestinal tract and systemically absorbed; IIa on the skin or in the nasal or oral cavity up to the pharynx; IIb in all other cases
22	7.9	Active therapeutic devices with an integrated or incorporated diagnostic function that significantly determines patient management	III

MDR Annex VIII Chapter III as in force on 6 November 2026; amendments to several rules are proposed but not adopted (see below).

How Each Rule Group Decides the Class

Each rule group starts from one question about the device, invasive or not, active or not, and the special rules then override the result where a substance, tissue, nanomaterial or closed loop is involved.

Non-Invasive Devices: Rules 1 to 4

Rule 1 is the fall-back for non-invasive devices: unless another rule applies, they are class I (MDR Annex VIII Section 4.1). Rule 2 (Section 4.2) keeps devices that channel or store liquids or gases for infusion or administration in class I, raises them to class IIa where they may be connected to a class IIa, IIb or III active device or serve for blood, other body liquids, organs, cells or tissues, and names blood bags as class IIb.

Rule 3 (Section 4.3) starts at class IIb for devices that modify the biological or chemical composition of blood, tissues or body liquids, drops to class IIa for filtration, centrifugation and gas or heat exchange, and rises to class III for substances in direct in vitro contact with human cells, tissues, organs or embryos before implantation or administration. Rule 4 (Section 4.4) grades devices for injured skin by the wound, from class I for mechanical barriers to class IIb for wounds that breach the dermis and heal only by secondary intent.

Invasive and Implantable Devices: Rules 5 to 8

Rule 5 covers devices invasive through a body orifice: class I for transient use, IIa for short-term use and IIb for long-term use, with lower classes in the oral cavity, ear canal and nasal cavity (MDR Annex VIII Section 5.1).

Rules 6 and 7 (Sections 5.2 and 5.3) set class IIa for surgically invasive devices in transient and short-term use. Both raise devices for the heart, the central circulatory system or the central nervous system to class III, and Rule 6 lowers reusable surgical instruments to class I.

Rule 8 (Section 5.4) sets class IIb for implantable and long-term surgically invasive devices, class IIa in the teeth and class III for the listed indents, such as breast implants, surgical meshes and joint replacements. MDCG 2021-24 rev.1 explains in Rule 8 Note 6 that non-implantable, non-active accessories of active implantable devices, such as magnets and programmers, are class III.

Active Devices: Rules 9 to 13

Active therapeutic devices that administer or exchange energy are class IIa under Rule 9, IIb where the energy is potentially hazardous or the device controls a class IIb active therapeutic device, and III where they control, monitor or directly influence an active implantable device (MDR Annex VIII Section 6.1).

Rule 10 (Section 6.2) places active devices for diagnosis and monitoring in class IIa, illumination in the visible spectrum in class I and monitoring of vital parameters with immediate danger in class IIb. Rule 12 (Section 6.4) places devices administering or removing substances in class IIa, or IIb where potentially hazardous, and Rule 13 (Section 6.5) leaves all other active devices in class I.

Rule 11 (Section 6.3) classifies software that informs diagnostic or therapeutic decisions as class IIa by default and as class IIb or III by severity, with the sub-rules in row 11 of the table. IVD software is classified under the IVDR rules and never under Rule 11, as MDCG 2019-11 rev.1 explains.

Special Rules 14 to 22

Rules 14 to 22 override the general groups: a device with a substance that would be a medicinal product with ancillary action, or with non-viable human or animal tissue, goes to class III (Rules 14 and 18).

Rule 15 places devices for contraception or the prevention of sexually transmitted diseases in class IIb, or III if implantable or long-term invasive. Rule 16 places disinfecting and sterilising devices in class IIa or IIb, Rule 17 places devices recording X-ray diagnostic images in class IIa, and Rule 19 grades nanomaterial by internal exposure, from class III down to class IIa.

Rules 20 and 21 cover inhalation devices and absorbed or locally dispersed substances by route and effect. Rule 22 places active therapeutic devices with an integrated or incorporated diagnostic function that significantly determines patient management in class III; MDCG 2021-24 rev.1 names closed-loop insulin delivery and automated external defibrillators among its examples.

The Implementing Rules of Chapter II

Before any rule is applied, MDR Annex VIII Chapter II sets how to apply them: the intended purpose governs, each device in a combination is classified separately, accessories are classified in their own right, and the highest resulting class applies. Three of these topics follow below, after the duration terms of Chapter I.

Duration of Use: Transient, Short Term and Long Term

MDR Annex VIII Chapter I defines duration as continuous use: transient is less than 60 minutes, short term is between 60 minutes and 30 days, and long term is more than 30 days (Sections 1.1 to 1.3).

The duration drives Rules 5 to 8, where the length of continuous use decides which rule and which class apply. Chapter I also defines the central nervous system as the brain, meninges and spinal cord (Section 2.7), the term behind the class III indents of Rules 6, 7 and 8. Section 3.7 adds that a device allows direct diagnosis when it provides the diagnosis by itself or decisive information for it.

Accessories and Devices Used in Combination

Under MDR Annex VIII Section 3.2, accessories for a medical device and for an Annex XVI product are classified in their own right, separately from the device they are used with. MDR Article 2(2) defines an accessory as an article that is not itself a medical device but is intended to enable one or more particular devices to be used in accordance with their intended purpose.

Chapter II also classifies each device used in combination with another device separately. Software follows a split rule under Section 3.3: software that drives or influences the use of a device falls within the same class as that device, while independent software is classified in its own right.

When Several Rules Apply: The Highest Class Wins

If several rules or sub-rules apply to the same device, the strictest rule resulting in the higher class applies (MDR Annex VIII Section 3.5). The rule works across groups and inside a single rule: a long-term implant placed in the teeth meets the class IIa indent of Rule 8, but if it also has a biological effect or is absorbed, it meets a class III indent, and class III applies.

Classifying a Device Step by Step

A device is classified in a fixed order: confirm that it is a medical device, an accessory or an Annex XVI product, check the special rules and software, then the active, invasive and non-invasive groups, apply the highest-class rule and finally check the class I sub-types. The six steps below follow that order, which is also the order of the class finder.

Qualify the product first: confirm what a medical device is under the MDR, whether the product is an accessory or an Annex XVI product, and whether it is one of the borderline products covered by the Commission's Manual on borderline and classification, Version 5 of April 2026, which has no binding force.
Check software against Rule 11 and Annex VIII Section 3.3.
Check the special Rules 14 to 22.
Apply the active Rules 9 to 13, then the invasive Rules 5 to 8, then the non-invasive Rules 1 to 4.
Apply Annex VIII Section 3.5 where several rules or sub-rules apply, so that the higher class wins.
Check the class I sub-types Is, Im and Ir, then follow the route of the class towards CE marking for medical devices.

The result and its reasoning belong in the technical documentation under MDR Annex II Section 1.1(f), so the classification and its justification are part of the MDR and IVDR technical documentation. A class found on this page or in the class finder is indicative only and is never a decision for a named device.

A Worked Example from MDCG 2021-24 rev.1

MDCG 2021-24 rev.1 Section 3.2 classifies a wound drainage system part by part: the cannula is class IIa under Rule 7, the tubing and the collector are class I under Rule 1, and the manufacturer may apply class IIa to the whole system. Read against Chapter II, the example shows the combination principle at work: every part is classified on its own before one class is chosen for the system.

What MDCG 2021-24 rev.1 Explains

MDCG 2021-24, the Medical Device Coordination Group's guidance on classification of medical devices, is current in revision 1 of April 2026, which replaces the original of October 2021, as of 6 November 2026. It explains how to read each of the 22 rules, with examples, and the Commission lists it under the heading "Borderline and Classification" on its page of MDCG guidance. The document itself is available as the MDCG 2021-24 rev.1 PDF on health.ec.europa.eu.

MDCG guidance is not legally binding: the MDCG acts under MDR Articles 103 and 105, and notified bodies take guidance into consideration under MDR Annex VII Section 1.6.2. For software, MDCG 2019-11 rev.1 of June 2025 explains qualification and classification, and every guidance document is listed by topic under MDCG guidance.

What Changed in April 2026

Revision 1 updates Section 2.1, reads the implantable definition with "clinical" instead of "surgical" intervention (Section 3.1.4), replaces "device" with "product" in Section 3.2, restructures Rule 9, adds notes 1 to 7 to Rule 8 and a new note to Rule 22, and updates the tables for Rules 2, 8, 10, 12, 16 and 22. The new wording of Section 3.1.4 matches MDR Article 2(5), which defines an implantable device by "clinical intervention".

The changes concentrate on Rules 8, 9 and 22, so manufacturers of implants, active therapeutic devices and closed-loop systems have the most reason to compare their classification rationale with revision 1.

Reclassification by Commission Implementing Act

The Commission can change the class of a device or group of devices by implementing act under MDR Article 51(3)(b), and the only such act so far is Implementing Regulation (EU) 2022/2347 of 1 December 2022, in force since 22 December 2022. It places skin-treatment lasers and intense pulsed light equipment (MDR Annex XVI Section 5) in class IIb, or class IIa for hair removal only, adipose-tissue reduction equipment (Section 4) in class IIb and brain stimulation equipment (Section 6) in class III, by way of derogation from Rule 13 (OJ L 311, 2.12.2022, p. 94). These product groups are described under Annex XVI products without a medical purpose.

Implementing Regulation (EU) 2022/2347 is distinct from Implementing Regulation (EU) 2022/2346, which sets the common specifications for Annex XVI products. The reclassification text is published on EUR-Lex as Implementing Regulation (EU) 2022/2347.

Classification Disputes and Who Decides Them

A dispute between a manufacturer and its notified body about the class of a device goes to the competent authority of the Member State where the manufacturer has its registered place of business, or, without one, where its authorised representative has it (MDR Article 51(2)).

In Germany, § 6 of the Medizinprodukterecht-Durchführungsgesetz (MPDG, the Medical Devices Implementation Act of 28 April 2020, Federal Law Gazette BGBl. I S. 960) gives this role for medical devices to the competent federal higher authority (zuständige Bundesoberbehörde). It decides disputes between manufacturer and notified body and, on application, the classification, the class I sub-type and the qualification of a product, and it should decide within 3 months. The national rules are set out under MDR and IVDR in Germany.

MDCG 2021-24 rev.1 and the borderline manual help each side argue its reading of a rule, while the authority decides under Article 51(2) on the basis of Annex VIII itself.

Pending Changes to the Classification Rules

As of 6 November 2026, the 22 rules apply unchanged; the Commission's proposal COM(2025) 1023 of 16 December 2025 (procedure 2025/0404(COD)) would change several of them, and it is pending at the stage "Awaiting committee decision" in the European Parliament's SANT committee. The past procedural events, as of 6 November 2026, include the SANT draft report of 30 June 2026; they are recorded in the legislative observatory file.

The proposal would rewrite Rule 11 with class I as the default for software and class III for critical situations, put reusable surgical instruments in class I regardless of the body part, limit the active-implantable indent of Rule 8 to the devices themselves by removing their accessories, and add dispute procedures. It proposes no change to the IVDR classification rules. Every amending act and the proposal are tracked under MDR and IVDR amendments.

Until an amending regulation is adopted and published, every current rule of Annex VIII applies.

Where the 22 Rules Stop

The 22 rules classify medical devices under the MDR only; in vitro diagnostic devices, devices under the repealed directives and devices outside the EU follow other systems. The three neighbouring systems are listed below.

In vitro diagnostic devices: classes A, B, C and D under IVDR Article 47 and seven rules in IVDR Annex VIII, explained under IVDR classification.
Devices under the repealed Directive 93/42/EEC: the Directive had 18 rules and no class Ir, as compared under MDD vs MDR.
Devices for the United States: the FDA classes form a separate system, compared under EU MDR vs FDA.

Why the Class Also Sets the Legacy End Date

The class also decides how long a legacy device with a Directive certificate may still be placed on the market: until 31 December 2027 for class III and class IIb implantable devices except the listed items, and until 31 December 2028 for all others, under MDR Article 120(3a) as amended by Regulation (EU) 2023/607 and only where the Article 120(3c) conditions are met. The class that counts is the class under the 22 rules (Commission Q&A on Regulation (EU) 2023/607, Q4), and the conditions are explained under the MDR transition period.

MDR Classification: The 22 Rules of Annex VIII and How to Classify a Medical Device

Summary