Annex IX Is the MDR Default — Annex X Never Works Alone

Regulation (EU) 2017/745 gives manufacturers more than one way to demonstrate conformity, and the route choice in Article 52 is not three independent menu items. Annex IX is a combined quality-management-system and technical-documentation assessment, and it is the default most manufacturers use. Annex X is type examination — and it is not a stand-alone route at all. It only becomes one once paired with Annex XI. Treating the three annexes as interchangeable options is where conformity assessment strategy goes wrong before a notified body is even involved.

Class sets the menu before route does

Conformity assessment route is downstream of classification, not a separate decision. A device's class under Annex VIII's classification rules determines which Article 52 procedures are even available, and how much of each one applies. Most Class I manufacturers never reach a notified body at all. Class IIa, IIb, and III manufacturers do, and for them the real decision is which combination of annexes the notified body will assess against — a choice worth making deliberately rather than defaulting to whatever a notified body's scope happens to offer first.

What each annex actually assesses

The three annexes examine different things, which is why swapping between them changes more than the paperwork volume:

• Annex IX — QMS plus technical documentation. Chapter I assesses the manufacturer's quality management system, covering both design and production. Chapter II is the notified body's review of the technical documentation itself, examined fully for Class III devices and on a representative sampling basis for Class IIa and IIb.
• Annex X — type examination. The notified body examines a representative sample (the "type") and certifies that it meets MDR requirements. This confirms the design is sound but says nothing about the manufacturer's ongoing production quality — which is exactly what it does not authorize on its own.
• Annex XI Part A — production quality assurance. The notified body audits the manufacturer's quality system for manufacturing and final inspection, not design. Used after Annex X has already addressed the design side.
• Annex XI Part B — product verification. Rather than auditing a quality system, the notified body examines or tests individual devices or statistically representative samples from production batches.

Annex X answers whether the design works. It was never built to answer whether the factory can reproduce it — that is Annex XI's job, every time. Why the pairing isn't optional

Where manufacturers get the route wrong

The most common error is not picking the wrong annex outright — it is treating Annex IX as pure paperwork once a notified body has accepted it, rather than as an ongoing relationship where the audit cadence and technical documentation sampling continue for the life of the certificate. The second most common error is assuming Class I status means no regulatory scrutiny at all. Article 52(7) self-declaration still requires a complete Annex II and III technical file; it only removes the notified body step for devices that are non-sterile, carry no measuring function, and are not reusable surgical instruments. Sterile Class I devices, measuring Class I devices, and Class Ir reusable surgical instruments all keep a notified body — just one scoped narrowly to the exception that triggered it.

None of this is a one-time decision filed away after initial certification. Conformity assessment route interacts with everything downstream of it — audit frequency, technical documentation update cadence, and how a gap assessment should even be scoped before a notified body transfer or a significant design change. Getting the route right at the outset, grounded in the device's actual class and design maturity rather than a notified body's default quote, is cheaper than renegotiating it after a nonconformity.