MDR Article 75: The 38-Day Clock After Notification

Regulation (EU) 2017/745, Article 75, gives a sponsor one week to notify a Member State of a substantial modification to a clinical investigation already underway. Teams that read that figure as the whole rule miss the second clock the article actually sets: the sponsor may implement the modification at the earliest 38 days after that notification, extendable by a further 7 days for expert consultation. Notification is not authorization — and the gap between the two is exactly where site and protocol timelines get built on the wrong date.

Two obligations, two different clocks

Article 75(1) sets the notification duty: a sponsor intending a modification likely to have a substantial impact on subject safety, health, or rights, or on the robustness or reliability of the investigation's data, must notify the Member State(s) concerned within one week, through the electronic system, with the reasons for and nature of the change and an updated version of the relevant EU MDR & IVDR Annex XV Chapter II documentation. That is a reporting deadline. The separate implementation bar — the earliest date the sponsor may actually put the modification into effect — runs from that same notification, not from a Member State approval the regulation does not require as a precondition to the clock starting.

Why the sponsor's own call is the exposure

Article 75 does not give the sponsor a pre-clearance mechanism for deciding whether a planned change is substantial in the first place — that determination is made by the sponsor, against the article's own test, before notification is even triggered. MDCG 2021-6 works through examples — changes to inclusion/exclusion criteria, statistical methodology, the investigational device itself, added sites, or a new sponsor — but the guidance illustrates the test rather than replacing the sponsor's judgment call. Get the classification wrong in the direction of "not substantial," and the exposure surfaces only when a Member State disagrees after the fact, not before implementation.

1. Decide against Article 75's test, deliberately. Evaluate impact on subject safety/health/rights and on the robustness or reliability of the data being generated — not against a checklist of "obviously substantial" changes.
2. Notify within one week — and treat that as the easy part. The electronic-system notification with updated Annex XV Chapter II documentation is a compliance deadline most sponsors already track.
3. Do not schedule implementation off the notification date. The earliest-38-days bar, not the one-week notification, is the date that actually governs when the change can take effect.
4. Build in the possible 7-day extension. A Member State consulting experts can push the bar to 45 days — close to the 45-day timeline for an entirely new clinical investigation application.

The one-week notification is the obligation everyone tracks. The 38-day implementation bar is the one that actually decides your timeline — and it starts on the same date, not a later one. Why the two clocks get confused

Where this collides with the rest of the investigation

A protocol amendment, a new site, or a change to the statistical analysis plan rarely arrives in isolation from the rest of an active investigation's operating rhythm — site initiation visits get scheduled, enrollment continues, and a clinical quality assurance team is already managing deviations against the current protocol version. Building the 38-day bar into that rhythm, rather than assuming the change lands the week it was notified, is the difference between a modification that absorbs cleanly and one that forces a retroactive protocol-deviation cleanup. For sponsors running an investigation instead of relying on the equivalence route under EU MDR, this is a live operational risk precisely because equivalence sponsors never encounter it at all.

None of this is unusual regulatory complexity; it is a sequencing problem that a European regulatory strategy built around the investigation's actual timeline, rather than around the notification deadline alone, handles without drama. Sponsors who treat the one-week notification as the finish line are the ones who find, five weeks later, that the change they already implemented was still inside its statutory waiting period.