---
title: Special Class I Devices Under MDR: Is, Im, Ir and the Notified Body
description: Class I Is, Im, and Ir devices still need a Notified Body under MDR Article 52(7). What that actually means for startups and budgets.
authors: Tibor Zechmeister, Felix Lenhard
category: Device Classification & Conformity
primary_keyword: Class I special Is Im Ir MDR notified body
canonical_url: https://zechmeister-solutions.com/en/blog/class-i-special-is-im-ir
source: zechmeister-solutions.com
license: All rights reserved. Content may be cited with attribution and a link to the canonical URL.
---

# Special Class I Devices Under MDR: Is, Im, Ir and the Notified Body

*By Tibor Zechmeister (EU MDR Expert, Notified Body Lead Auditor) and Felix Lenhard.*

> **Class I is not a single bucket under MDR. If your device is supplied sterile (Is), has a measuring function (Im), or is a reusable surgical instrument (Ir), MDR Article 52(7) requires Notified Body involvement. Limited in scope, but mandatory. Founders routinely budget for "Class I self-certification" and then discover they are not self-certifying at all.**

**By Tibor Zechmeister and Felix Lenhard.**

## TL;DR
- Class I under MDR splits into plain Class I (self-certification) and three special subcategories: Is, Im, and Ir.
- Class Is (sterile), Class Im (measuring function), and Class Ir (reusable surgical instruments) require a Notified Body per MDR Article 52(7).
- The Notified Body scope is limited. It audits only the specific aspect that makes the device "special" (sterility assurance, metrological requirements, or reprocessing).
- You still issue your own EU Declaration of Conformity, but it cites the Notified Body certificate for the limited scope.
- Founders who budget for a clean self-certification path and then discover Is/Im/Ir status often lose three to six months and five-figure sums on unplanned NB engagement.

## Why this matters

A founder walks into Tibor's first session with a wound dressing. "Class I," she says confidently. "We're self-certifying." Then Tibor looks at the label: "Sterile." And the whole plan changes.

Class I under MDR is not one box. It is four. Plain Class I devices. The ones most founders picture when they hear "Class I". Can genuinely be self-certified. No Notified Body, no surveillance audits, no certificate fees. But the moment your device crosses into sterile supply, has a measuring function, or is a reusable surgical instrument, MDR pulls a Notified Body into the picture. Not for the whole device. Just for the specific aspect that makes it "special." But still: a Notified Body, with a contract, an audit, a certificate, and an annual bill.

This post walks through what Is, Im, and Ir actually mean, what the Notified Body's scope is in each case, and how to plan for it before your timeline and budget take the hit.

## What MDR actually says

The governing text is MDR Article 52(7). It reads (close paraphrase):

> For Class I devices placed on the market in a sterile condition, devices with a measuring function, or reusable surgical instruments, the manufacturer shall follow the procedures set out in Annex IX Chapters I and III, or Annex XI Part A. The involvement of the Notified Body in those procedures shall be limited:
> - for devices placed on the market in sterile condition, to the aspects relating to establishing, securing and maintaining sterile conditions;
> - for devices with a measuring function, to the aspects relating to the conformity of the devices with the metrological requirements;
> - for reusable surgical instruments, to the aspects relating to the reuse of the device, in particular cleaning, disinfection, sterilisation, maintenance and functional testing and the related instructions for use.

Annex VIII is where the classification rules live, and the underlying definitions of "sterile," "measuring function," and "reusable surgical instrument" are anchored in MDR Article 2 and the classification rules themselves.

In plain language: you still run the Class I route overall. You still own the technical documentation. You still sign your own EU Declaration of Conformity per MDR Article 19. But for the one specific aspect that triggered the "special" status, a Notified Body has to audit and certify. And its certificate number goes on your Declaration of Conformity alongside your own self-certification for the rest of the device.

### Class Is. Sterile supply

If your device is supplied to the end user in a sterile state, you are Class Is. The Notified Body reviews your sterilisation process validation, your sterile barrier system, your bioburden controls, your routine batch release, and your shelf-life of sterility. The scope is everything that touches "is this device actually sterile when it reaches the patient, and will it stay that way."

### Class Im. Measuring function

If your device has a measuring function. That is, it quantitatively measures a physiological or anatomical parameter, or a quantity of energy or substance delivered to or removed from the body, and the result is displayed in legal units of measurement. You are Class Im. The Notified Body reviews the metrological requirements: accuracy, precision, calibration, uncertainty budgets. MDCG 2021-24 (classification guidance) provides interpretation on what counts as a "measuring function" versus a device that merely displays a value for indicative purposes.

### Class Ir. Reusable surgical instruments

A reusable surgical instrument is an instrument intended for surgical use by cutting, drilling, sawing, scratching, scraping, clamping, retracting, clipping or similar procedures, without connection to any active device, and which the manufacturer intends to be reused after appropriate procedures such as cleaning, disinfection and sterilisation. Class Ir was introduced as a new MDR category. Under the old MDD these were plain Class I. The Notified Body now audits the reprocessing validation: cleaning, disinfection, sterilisation, functional testing, maintenance, and the related instructions for use.

## A worked example

Take a startup making a laparoscopic grasper. Titanium tip, reusable, supplied non-sterile, hospital sterilises before each use. Under MDD, this would have been plain Class I. Self-certification, done. Under MDR, it is Class Ir.

Here is what changes:

- **Technical documentation:** Annex II and III, same as any other device. The reprocessing section gets significantly more attention. Validated cleaning protocol, disinfection validation, steam sterilisation validation (typically ISO 17664 and ISO 17665 references), functional testing after N cycles, end-of-life criteria.
- **QMS:** Still need an ISO 13485:2016+A11:2021 compatible QMS covering the full product lifecycle.
- **Notified Body engagement:** Contract a Notified Body. They audit the reprocessing aspect only. They do not certify your full QMS, they do not certify your full technical file. They issue a certificate covering the reuse aspects.
- **Cost reality:** Budget roughly 15,000-35,000 EUR for the initial NB engagement (application, review, audit, certificate issuance) plus annual surveillance. Exact numbers vary by NB and device complexity.
- **Timeline reality:** Add three to six months to your CE marking timeline versus a plain Class I plan. NB capacity is the bottleneck, not your readiness.
- **Declaration of Conformity:** You sign it yourself. It cites the NB certificate for the Ir aspects and your self-assessment for everything else.

The founder who budgeted "Class I, no NB, six months to CE" is now staring at "Class Ir, NB contract, nine to twelve months to CE, extra 25,000 EUR." That is not a small delta for a pre-revenue startup.

## The Subtract to Ship playbook

Class I special status is not avoidable through clever intended-purpose drafting. If the device is sterile, it is sterile. But the budget and timeline consequences are absolutely avoidable through early, honest classification. Here is the lean path:

1. **Classify first, build second.** Before you lock the intended purpose, before you finalise the design, before you write a single line of technical file prose, classify the device per MDR Article 51 and Annex VIII. Write a classification justification document that names the rule and the outcome: "Rule 1, non-invasive, Class I, supplied sterile, therefore Class Is per Article 52(7)."
2. **If you can realistically avoid sterile supply, do.** For some devices, non-sterile supply with user-sterilisation is a legitimate option and removes Class Is entirely. For others (implants, sterile-field devices), it is not negotiable. Make this a conscious design decision, not an accident of packaging.
3. **If measuring function is tangential to the clinical purpose, ask whether you really need it in legal units.** A device that displays heart rate "for reference" is different from a device that measures heart rate as a clinical parameter. MDCG 2021-24 and the Borderline Manual v4 give interpretation. Get an auditor's view before you lock the IFU language.
4. **Engage a Notified Body early for Is/Im/Ir.** Not because you need a full QMS audit. You do not. But because NB capacity is tight, and even the limited-scope engagement needs a slot on their schedule. Contact two or three NBs six to nine months before you need the certificate.
5. **Keep your QMS lean but auditable.** The Notified Body audit scope is limited, but they will still look at the processes that touch the special aspect. For Class Is, that means sterilisation process controls, change control on the sterile barrier, CAPA related to sterility failures. Build the QMS so those processes are visible without drowning the rest in bureaucracy.
6. **Budget honestly on the regulatory slide.** When you pitch investors, a Class Is device is not "Class I, self-certification, minimal regulatory cost." It is "Class Is, limited Notified Body involvement for sterility, approximately 25,000 EUR initial plus annual surveillance, nine to twelve month CE timeline." Investors respect precision. They punish surprises.

The Subtract to Ship point here is blunt: Class I special status is one of the most common budget killers Tibor sees in first-time founders. It is not hidden. MDR Article 52(7) is right there. But it is easy to miss if founders default to "Class I equals self-certification." Classify honestly, plan for the NB engagement, and the cost is manageable. Discover it six months in and it is painful.

## Reality Check

1. Have you formally classified your device per MDR Article 51 and Annex VIII, with a written justification citing the specific rule?
2. Is your device supplied sterile? If yes, have you budgeted for Class Is Notified Body engagement?
3. Does your device have a measuring function in legal units of measurement that drives clinical decisions? If yes, have you reviewed MDCG 2021-24 for Im interpretation?
4. Is your device a reusable surgical instrument? If yes, have you validated reprocessing (cleaning, disinfection, sterilisation) per applicable ISO standards?
5. Have you contacted Notified Bodies about the limited-scope engagement, and do you understand their timeline capacity?
6. Does your regulatory budget reflect Is/Im/Ir Notified Body costs plus annual surveillance, or does it still assume clean self-certification?
7. Does your Declaration of Conformity template correctly cite the NB certificate number for the limited scope?
8. Is your QMS structured so the special-aspect processes (sterilisation, metrology, reprocessing) are clearly auditable without over-engineering the rest?

## Frequently Asked Questions

**Do I need a full QMS audit under ISO 13485 if my device is Class Is?**
The Notified Body scope is limited to sterility aspects per MDR Article 52(7). You do not get a full ISO 13485 certification from that engagement. However, you still need an ISO 13485:2016+A11:2021 compatible QMS as your own responsibility under MDR Article 10(9). Many startups choose to pursue separate ISO 13485 certification for commercial and audit-readiness reasons.

**Can I self-certify the non-sterile version of my device and skip the NB?**
Yes, if you supply non-sterile and the end user sterilises. You are then plain Class I. But your IFU must clearly specify the sterilisation procedure, and you lose any marketing claim of "sterile as supplied." For some clinical workflows this is a real option; for others it is not.

**What exactly is a "measuring function" under MDR?**
A measuring function exists when the device measures, with quantitative accuracy, a physiological or anatomical parameter or a quantity of energy or substance, and the result is displayed in legal units of measurement and is used for diagnostic or therapeutic decision-making. Display of a value for informational purposes only is typically not a measuring function. MDCG 2021-24 provides detailed interpretation.

**If my Notified Body only audits the sterility aspect, who is responsible for the rest of the technical file?**
You are. Class Is is still a self-declaration route overall. You sign the EU Declaration of Conformity per MDR Article 19, you own the technical documentation per Annex II and III, and you are liable for the full GSPR compliance per Annex I. The Notified Body's limited-scope certificate covers only the specific aspect that triggered the special status.

**Were reusable surgical instruments always a special Class I category?**
No. Class Ir was introduced with MDR. Under the old MDD, reusable surgical instruments were plain Class I and self-certified. The MDR change recognised that reprocessing validation needed independent verification. Legacy devices transitioning from MDD to MDR under the extended transition periods of Regulation (EU) 2023/607 need to plan for Class Ir NB engagement as part of their MDR transition.

**How do I choose a Notified Body for a limited-scope engagement?**
Check their designation scope. Not all NBs cover all Class I special categories. Ask specifically about Is, Im, or Ir experience. Ask about timeline capacity. Ask about the review fee structure for limited-scope engagements versus full QMS audits. Get quotes from at least two.

## Related reading
- [Class I Medical Devices Under MDR](/blog/class-i-medical-devices-under-mdr) – the full Class I picture including the special subcategories.
- [Conformity Assessment Class I Checklist](/blog/conformity-assessment-class-i-checklist) – step-by-step for the self-certification portion.
- [Technical Documentation for Class I. Minimum Viable](/blog/technical-documentation-class-i-minimum-viable) – what the tech file actually needs to contain.
- [MDR Device Classification Explained](/blog/mdr-device-classification-explained) – the full Annex VIII classification framework.
- [Choose the Right Notified Body](/blog/choose-right-notified-body) – how to select an NB when you only need limited-scope certification.

## Sources
1. Regulation (EU) 2017/745 on medical devices, consolidated text. Article 52(7), Annex VIII, Annex IX Chapters I and III, Annex XI Part A.
2. MDCG 2021-24 (October 2021). Guidance on classification of medical devices.
3. EN ISO 13485:2016+A11:2021. Medical devices. Quality management systems. Requirements for regulatory purposes.

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*This post is part of the [Device Classification & Conformity](https://zechmeister-solutions.com/en/blog/category/classification) cluster in the [Subtract to Ship: MDR Blog](https://zechmeister-solutions.com/en/blog). For EU MDR certification consulting, see [zechmeister-solutions.com](https://zechmeister-solutions.com).*