MDD to MDR Transition: What Changes for Medical Device Companies

The EU Medical Device Regulation has been in force since 2017 and mandatory since 26 May 2021. Most manufacturers reading this still hold MDD certificates and are working through the migration from MDD to MDR. The grace periods set by Regulation 2023/607 extended the runway until 31 December 2027 for higher-risk devices and 31 December 2028 for the rest, but they came with conditions that catch teams out.

This raises a practical question:
How do you take a device certified under MDD and steer it cleanly through the MDR transition, without re-doing every artefact from scratch and without missing the deadline?

This guide walks through what changes in the MDD to MDR transition, the deadlines that moved (and the conditions that keep your certificate valid), the Rule 11 trap that re-classifies most stand-alone software upward, the heavier clinical evaluation lift, the structurally different post-market regime and the failure modes we see when medical device companies make the move. By the end you will have a workable mental model of where you stand and what is still ahead.

Table of Content

Why the MDD to MDR Transition Matters Now

The Medical Device Directive (MDD, 93/42/EEC) governed how medical devices reached the European market for around 25 years. The Medical Device Regulation, Regulation 2017/745, replaced it in 2017 and became mandatory in May 2021. For the bulk of devices already on the market, the practical move from MDD to MDR has been a multi-year undertaking that most teams underestimated when they started.

The MDR introduces structural changes across the regulation, with a stricter classification logic, especially for software. So the clinical evidence requirements have changed.

The Post-market Obligations

The post-market obligations are structurally heavier and the technical documentation has moved to a different Annex structure (Annex II and III). That means for a device that has lived under MDD self-certification or a long-standing notified body relationship, the transition often surfaces gaps in design controls, risk management and clinical evaluation that have been quietly accumulating for years.

The 2023/607 Extension Regulation

The 2023/607 extension regulation moved the deadlines but tightened the conditions. Now Class III and implantable Class IIb devices have until 31 December 2027. Class IIa, Class IIb non-implantable and certain Class I devices have until 31 December 2028.

Manufacturers Conditions

Also, the extension comes with conditions. Manufacturers must have a formal application lodged with a notified body, an MDR-aligned QMS in place and no significant change to the device. Significant change is itself a defined term under MDCG 2020-3 and we walk through it later in this guide.

The result for any team still on an MDD certificate is two parallel work streams. First is, keeping the MDD certificate valid through the grace period, which means avoiding any change that triggers loss of transitional status. Second is building the MDR submission underneath, with enough lead time on the notified body queue to certify before the cliff.

-> In short: the transition is structurally bigger than a documentation update and the 2027 to 2028 cliffs are closer than they look once notified body queues are factored in.

What To Do:

Pin down which deadline applies to each product in the portfolio (Class III and implantable IIb hit the 2027 wall, everything else 2028).
Verify the MDR-aligned QMS is genuinely in place under ISO 13485:2016, not just on paper.
Map every planned change to the MDCG 2020-3 significant-change definition before it lands.

The Three MDD to MDR Changes That Bite

The MDD to MDR transition involves dozens of changes across the regulation. Three of them carry most of the operational weight.

The First is Classification

The MDR introduces a stricter, risk-based approach and Annex VIII is extended plus Rule 11 is added specifically for software. Under the old MDD, stand-alone software was almost always Class I, which manufacturers could self-certify.

Under MDR, around seventy percent of stand-alone software now lands in Class IIa or higher, which requires a notified body. For a digital health product certified under MDD self-certification, this single change can shift the entire conformity assessment route from declare-and-ship to a full notified body audit.

The Second is Clinical Evidence

Under MDD, manufacturers leaned heavily on equivalence claims and literature reviews, but under MDR, the bar is higher.

Article 61 and the corresponding MDCG guidance (especially MDCG 2020-13) set out a structured clinical evaluation pathway with real bite. Equivalence claims are harder to defend in practice and for Class IIb and Class III devices, clinical investigation data is often required. Teams that planned a literature review and an equivalence claim under MDD often discover a clinical study in their path under MDR.

The Third is Post-market

MDR defines a full post-market surveillance system anchored in Articles 83 to 86, with a PMS plan, a PSUR (Periodic Safety Update Report) reviewed by the notified body for Class IIa and above, mandatory Post-Market Clinical Follow-up (PMCF) for most devices above Class I and reporting flows through the EUDAMED database. The vigilance timelines are also tighter: serious incidents within 15 days, deaths and serious public health threats within 2 days.

-> In short: classification, clinical evidence and post-market are the three changes that turn the transition from a documentation exercise into a structural re-build.

What To Do:

Run a provisional MDR classification on every product before committing to a transition plan.
Audit the existing clinical evidence against MDCG 2020-13 expectations early.
Build the PMS, PSUR and PMCF system in parallel with the technical file, not after.

Rule 11 and the Software Reclassification Trap

Rule 11 is the single most disruptive change for digital health products in the MDD to MDR transition. We have a dedicated explainer on it in our Software as a Medical Device piece where we focus on what it means specifically for teams in transition.

Also Rule 11 covers software intended to provide information used for diagnosis or treatment. Plain reading: any software that informs a clinical decision is in scope, which most digital health products are.

Patient monitoring apps, decision-support tools, image analysis software, clinical scoring algorithms and even some symptom checkers all qualify under the rule. Additionally the classification logic is layered. First, software that provides information used for decisions with diagnosis or therapeutic purposes lands at least at Class IIa. Second, software providing information that could cause serious deterioration in health or surgical intervention lands at Class IIb.

Third, software providing information that could cause death or irreversible deterioration lands Class III. The result for the stand-alone software population: most products move up at least one class compared to their MDD-era position.

So the operational consequences are substantial. A Class I self-certified MDD product becomes a Class IIa MDR product that needs a notified body audit of the QMS against ISO 13485, a technical documentation review against MDR Annex II and III, a clinical evaluation that meets MDCG 2020-13 expectations and a post-market system aligned with Article 83. Also the engagement timelines with the notified body run 12 to 18 months.

So we see a common pattern: Most teams meet Rule 11 for the first time at the door of the notified body, not in the design files.

-> In short: Rule 11 reclassifies most stand-alone software upward and the implications cascade through every regulatory artefact.

What To Do:

Re-classify every software product under MDR Annex VIII Rule 11 now, before the certificate expires.
Read MDCG 2019-11 once and use it as the working interpretation of Rule 11.
Brief the notified body on the proposed classification before the technical file is built.

Clinical Evaluation Under MDR: the Heavier Lift

Clinical evaluation is where MDD to MDR transitions most often stall.

Under MDD

A literature review backed by an equivalence claim was a workable strategy for most Class IIa devices. The equivalence argument let manufacturers point to published evidence on a comparable device, demonstrate that their device performed similarly and avoid running their own clinical investigation.

Under MDR

That route is much harder. Article 61 sets a higher bar for what counts as equivalent and MDCG 2020-13 codifies the structure of the Clinical Evaluation Assessment Report (CEAR) and the depth of evidence expected.

For Class IIb and Class III devices, equivalence claims rarely hold and clinical investigation data is usually required. For Class IIa, equivalence is possible but the documentation expected is considerably heavier than what passed under MDD.

During Transition

So the practical effect during transition is that a team which comfortably defended a clinical evaluation under MDD often finds the same evaluation rejected on first MDR review. The CEAR has to be rebuilt with explicit traceability between intended use, claimed performance, clinical data sources and residual risk. Where equivalence is no longer defensible, a clinical investigation has to be planned, recruited, executed and analysed, typically eighteen to thirty-six months added to the launch timeline.

The Post-Market Clinical Follow-up (PMCF) plan is the other half of this picture. Under MDR, PMCF is mandatory for most devices above Class I. The plan is submitted with the original technical documentation and updates run on a defined cadence.

-> In short: clinical evaluation is the lift that catches MDD-era teams off-guard most often during the transition.

What To Do:

Audit the current Clinical Evaluation Report against MDCG 2020-13 before the notified body submission.
Decide early whether equivalence holds or a clinical investigation is needed.
Submit the PMCF plan with the technical file, not as a follow-on.

Post-market Obligations: PMS, PSUR and EUDAMED

The post-market regime under MDR is structurally different from MDD vigilance.

Articles 83 to 86 of the MDR define a complete post-market surveillance system. The PMS plan is a required document and must specify how the manufacturer collects and reviews data from complaints, vigilance reports, scientific literature, registries, real-world clinical evidence and any other relevant source. Additionally the cadence of review is defined.

PSUR

For Class IIa and above, the PSUR (Periodic Safety Update Report) is the next layer. The PSUR pulls together post-market findings, adverse events, trends and risk-benefit re-assessment on a defined schedule. For Class III and implantable devices it runs annually and is reviewed by the notified body. And for Class IIa and Class IIb it runs every two to five years depending on class.

PMCF

PMCF is mandatory for most devices above Class I. The plan defines what data is collected from real-world use, how it feeds back into the clinical evaluation and on what cadence the CEAR is updated. So PMCF can run through registries, surveys, structured follow-up studies or a combination.

EUDAMED

EUDAMED is the European database. The UDI (Unique Device Identifier), the device registration, the certificate, vigilance reports and PMS results all flow through it. Their vigilance reporting timelines are tight: serious incidents within 15 days, deaths and serious public health threats within 2 days.

-> In short: the MDR post-market regime is a permanent operational commitment that needs ownership, cadence and tooling from day one.

What To Do:

Resource a PMS function with named ownership before the transition submission.
Schedule the first PSUR review at month 12 (Class IIa) or month 6 (Class IIb and III).
Confirm EUDAMED registration and UDI alignment well ahead of the MDD certificate expiry.

The Transition Timeline and the 2027 to 2028 Grace Periods

Most teams know the MDR deadline got extended, but have the details wrong about the current MDD to MDR transition timeline.

The base MDR date of application was 26 May 2021. Originally, MDD certificates issued before that date were valid until 26 May 2024, with a wider transition until 26 May 2025 for products sold under those certificates.

Regulation 2023/607

Regulation 2023/607 changed that. Class III and Class IIb implantable devices now have MDD certificates valid until 31 December 2027. Also the Class IIb non-implantable, Class IIa and Class I (with notified body involvement) have certificates valid until 31 December 2028 and Class I devices that did not require notified body involvement under MDD already needed to comply with MDR by 26 May 2021.

The extension comes with six conditions that must all be met to stay under the transitional provisions. One, the manufacturer must hold an MDD certificate that was valid on 26 May 2021 and remains valid. He also must continue to comply with MDD requirements for the device.

No significant change in design or intended purpose is permitted (MDCG 2020-3 defines this). A formal MDR application must be lodged with a notified body by the relevant intermediate deadline. And a written agreement with a notified body must be in place. On top of that the manufacturer must maintain an MDR-aligned QMS.

Miss any one of these conditions and the MDD certificate stops being valid as a transition vehicle. The product can no longer be placed on the market until MDR certification is granted.

Here the notified body queue is the practical bottleneck. Lead times from formal application to certificate are running at 12 to 18 months in 2026 and the queue is expected to tighten as the 2027 cliff approaches. A team that starts engagement in early 2026 for a Class III device has a realistic path, but a team starting in early 2027 likely does not.

-> In short: the 2027 and 2028 cliffs are real, the extension comes with conditions and the notified body queue is the rate-limiting factor.

What To Do:

Confirm which cliff applies to each product and document it in the transition plan.
Verify every condition of the transitional provisions is met for each product on an MDD certificate.
Lock in notified body capacity at least 18 months before the relevant cliff.

Where Teams Trip up in MDD to MDR Migrations

Across the MDD to MDR projects we have worked on, five failure modes recur. None of them are unusual and they can all be avoided by adopting a few specific habits.

1. Significant Change Misread

A planned design update, software release or label change is treated as routine maintenance, but it qualifies as a significant change under MDCG 2020-3. The second might be that the MDD certificate stops being valid as a transition vehicle. Or third, product comes off the market until MDR certification lands.

Fix: every change goes through a formal MDCG 2020-3 review before implementation, owned by the regulatory function rather than engineering.

2. Technical File Treated as a Refresh

The MDD technical file follows a different structure from the MDR Annex II and III file. So section by section the content is broadly similar, but the traceability between intended use, classification, design inputs, risk controls, verification and post-market is structurally different. A refresh approach leaves audit-grade gaps in traceability.

Fix: rebuild the technical file against Annex II and III from scratch. Do not paste MDD content into MDR section headings.

3. Clinical Evaluation Underestimated

Literature review and equivalence are assumed to carry over from the MDD CER. Or the notified body asks for the full MDCG 2020-13 structure and, often, clinical investigation data the team did not plan for. Eighteen to thirty-six months added to the transition timeline is a common root for mistakes too.

Fix: validate the clinical evidence strategy with the notified body at the application stage, not at first review.

The pattern is consistent across the MDD to MDR projects we see. Teams that postponed design history discipline under MDD pay it back in concentrated form during the transition.

4. Late Notified Body Engagement

The team plans to submit twelve months before the cliff and the notified body lead time is fourteen months. So the certificate expires before the audit completes.

Fix: engage the notified body 18 months before the cliff at minimum. Accept that the queue may push deeper into 2027 as more manufacturers compete for capacity.

5. PMS Built as a Vigilance Refresh

MDR PMS is structurally heavier (PMS plan, PSUR, PMCF, EUDAMED) and the team treats it as a vigilance refresh. But the notified body finds the gap at audit.

Fix: design the post-market system from MDR Articles 83 to 86 directly, not as an evolution of MDD vigilance.

-> In short: the five failure modes are individually avoidable and they become fatal when a team accumulates two or three in parallel during the transition.

FAQs: MDD MDR Questions Teams Keep Asking

How long does the MDD to MDR transition actually take?

A1: For a Class IIa device with a clean MDD history, twelve to twenty-four months from notified body engagement to MDR certificate, assuming the technical documentation and clinical evaluation are in good order. Class IIb non-implantable runs eighteen to twenty-four months. Class IIb implantable and Class III run two to three years. Most of the variance is in the clinical evaluation and the notified body queue.

Q2: What counts as a significant change during the transition?

A2: MDCG 2020-3 is the operative guidance. Changes to intended use, classification, design that affects safety or performance, sterilisation method or software functionality above a threshold are significant. But notified body engagement, manufacturing site changes or minor label updates are not. The judgment call sits with the regulatory function and is best made formally, in writing, before the change goes live.

Q3: Is my software a medical device under MDR?

A3: If it is intended to provide information used for diagnosis, prediction, prognosis, treatment monitoring or treatment recommendation, then under MDR Rule 11 it almost certainly is and most software falls into Class IIa or higher. MDCG 2019-11 is the operative guidance for this. Mobile apps, web portals, decision-support tools and AI inference layers all qualify under the same rule.

Q4: Can I continue selling under my MDD certificate during the transition?

A4: Yes, if all conditions of the 2023/607 extension are met. Most importantly: no significant change under MDCG 2020-3, formal MDR application lodged with a notified body, written agreement with that notified body and an MDR-aligned QMS in place. Miss any condition and the MDD certificate is no longer valid as a transition vehicle.

Q5: What is the biggest difference between MDD and MDR in practice?

A5: Three things, in order of operational impact. First, software classification: Rule 11 pushes most digital health products up by one or two classes. Second, clinical evidence: equivalence claims are harder to defend and clinical investigation is often required. Third, post-market: PMS plan, PSUR, PMCF and EUDAMED reporting are heavier than MDD vigilance.

Closing Thoughts

The MDD to MDR transition is one of the few regulatory shifts where the cost of treating it as paperwork is paid in years. The teams that come through the transition cleanly treat it as a programme: classification first, technical file rebuilt, clinical evaluation upgraded, post-market system designed from MDR Articles 83 to 86 and notified body locked in well ahead of the relevant cliff.

If you are mid-transition and want a second pair of eyes on classification, on the clinical evaluation strategy, on the technical file or on the timeline against your notified body queue, that is exactly the work our MDR Consulting service exists for.