EU MDR classification rules: how to classify a medical device under Annex VIII
A practical walkthrough of EU MDR classification: the Annex VIII rules, Class I to III, Rule 11 for software, and what each class means for conformity assessment.
Under Regulation (EU) 2017/745, classification is not a formality — it decides whether you can self-certify, whether a notified body is involved, and how much clinical evidence you need. It is set by the twenty-two rules in Annex VIII.
The four classes
Class I covers the lowest risk, with sub-categories Is (sterile), Im (measuring function) and Ir (reusable surgical instruments), each of which brings a notified body into scope for that specific aspect. Class IIa and IIb cover increasing risk and require notified body involvement in conformity assessment. Class III covers the highest risk, including most implantables and devices incorporating a medicinal substance.
How the Annex VIII rules work
The rules are grouped: non-invasive devices, invasive devices, active devices, and special rules. Apply every rule that could apply, then take the strictest resulting class. Duration of use matters — transient, short term or long term — as does whether a device is invasive, and by which route.
Accessories are classified in their own right, not inherited from the device they support. Software that drives or influences a device falls in the same class as that device.
Rule 11 and software
Rule 11 is where most digital health teams land. Software intended to provide information used for diagnostic or therapeutic decisions is Class IIa; if those decisions could cause death or an irreversible deterioration of health, Class III; if serious deterioration or surgical intervention, Class IIb. Software intended to monitor physiological processes is Class IIa, rising to IIb where the monitored parameters are vital and variations could result in immediate danger. Everything else falls to Class I.
In practice Rule 11 pushed a large share of previously self-certified software up into notified body territory. Plan notified body capacity early — availability, not readiness, is often the binding constraint.
What follows from the class
Class determines your conformity assessment route under Annexes IX to XI, the depth of clinical evaluation under Article 61 and Annex XIV, and your post-market clinical follow-up obligations. Class IIa and above also change the technical documentation sampling your notified body will perform.
How DevicePath helps
DevicePath returns high-level EU MDR and UK (UKCA / MHRA) considerations alongside FDA classification, product codes, premarket pathway and 510(k) predicate candidates, from a plain-language device description. It is open source, and designed as the first triage pass for start-ups, SaMD teams and small-to-mid-size manufacturers.