Machinery Regulation guide
Substantial modification: when a retrofit makes you the manufacturer
Defined by law for the first time: Art. 3(16) says when a modification is substantial, and Art. 18 what follows.
In short
Under Art. 3(16) of Regulation (EU) 2023/1230 a substantial modification is a physical or digital modification of a machine after its placing on the market or putting into service that is not foreseen or planned by the manufacturer and affects safety by creating a new hazard or increasing an existing risk, so that guards or protective devices requiring an adaptation of the safety control system, or additional protective measures for stability or strength, become necessary. Whoever carries it out is deemed a manufacturer under Art. 18 and is subject to the obligations of Art. 10: risk assessment, technical documentation, instructions, conformity assessment, EU declaration of conformity and CE marking for the modified machine.
The definition in Art. 3(16)
Under the Machinery Directive, substantial modification was defined only by national guidance. The Machinery Regulation defines it in the legal text for the first time. Three elements must coincide:
- The modification is not foreseen or planned by the manufacturer and takes place after placing on the market or putting into service, physically or digitally, i.e. also through software changes.
- It affects safety: a new hazard arises or an existing risk increases.
- As a result, guards or protective devices whose integration requires adapting the existing safety control system, or additional protective measures to ensure stability or strength, become necessary.
What is not substantial
Conversely: repair and replacement with equivalent parts, retrofits and options foreseen by the manufacturer, changes without a new hazard or increased risk, and changes where the new hazard is controlled by simple protective measures without adapting the safety control system. The evidence is the risk assessment; without documentation you cannot later show why the change was not substantial.
The consequence: Art. 18 makes the modifier the manufacturer
Whoever carries out a substantial modification is deemed a manufacturer for the purposes of the Regulation and is subject to the obligations in Art. 10 for that machine. If, according to the risk assessment, the modification only affects the safety of one machine within an assembly of machinery, the obligations are limited to that machine. To be created or updated for the modified machine:
- Risk assessment under Annex III No. 1, including interfaces to the unchanged part.
- Technical documentation under Annex IV Part A, kept for ten years.
- Instructions under Annex III 1.7.4 describing the modified state; the original manual remains part of the documentation.
- Conformity assessment under Art. 25, with a notified body where Annex I applies.
- EU declaration of conformity under Annex V Part A and new CE marking with the modifier as manufacturer.
Documentation of the modified machine
After a substantial modification two sets of documents exist: the original manufacturer’s documentation and the documentation of the modification. Both must be retrievable at the machine, clearly separated and dated. Digitally this is straightforward: one access point per machine, one folder for the original documentation, one for the modification with the new declaration of conformity, versioned, with the risk assessment as a protected document. The QR code on the machine stays the same.
FAQ
Frequently asked questions
Is a software update a substantial modification?
It can be. Art. 3(16) explicitly covers digital modifications. An update that changes safety functions, enables new operating modes or shifts limit values may create a new hazard and require adapting the safety control system. An update foreseen and released by the manufacturer is not a substantial modification, because it is planned by the manufacturer.
Who becomes the manufacturer after a substantial modification?
The natural or legal person carrying out the modification: the operator if it modifies the machine itself, or the integrator or service company responsible for the modification. This should be settled contractually before the retrofit.
Does the whole machine have to be reassessed?
In principle the manufacturer obligations apply to the modified machine. If, according to the risk assessment, the modification only affects one machine within an assembly, Art. 18 limits the obligations to that machine. Within a single machine, the risk assessment is where the scope is justified.
Legal basis and sources
What this page is based on
- Regulation (EU) 2023/1230 on machinery (Machinery Regulation) — EUR-Lex
- Directive 2006/42/EC (Machinery Directive) — EUR-Lex
- German Ordinance on Industrial Safety and Health (BetrSichV) — gesetze-im-internet.de
- DGUV Test: CE marking and conformity assessment
- German Product Safety Act (ProdSG) — gesetze-im-internet.de
The regulation or standard itself is authoritative. This page is an expert summary, not legal advice.
Keep reading
More chapters of this guide
Machinery Regulation: Deadlines and Transition until 20 January 2027
A hard cut-off date instead of a transition period: from 20 January 2027, every placing on the market is governed exclusively by the Machinery Regulation.
Digital Operating Instructions under the Machinery Regulation: What Is Permitted
Paper is no longer mandatory: Article 10(7) permits digital operating instructions — subject to four conditions.
Technical Documentation under the Machinery Regulation: Scope, Retention, Access
From risk assessment to declaration of conformity: what must remain deliverable for 10 years — and what may stay protected.
QR Code on the Machine: How It Satisfies the Machinery Regulation
The Machinery Regulation does not prescribe a QR code — but it does require a permanent digital access route. The code is the de facto standard.
Declaration of Conformity under the Machinery Regulation: What Changes on 20 January 2027
The legally binding document behind the CE marking: what belongs in it — and what changes on 20 January 2027.
Risk Assessment under the Machinery Regulation: Obligation, Process, Documentation
No CE marking without a risk assessment: the process according to ISO 12100 — and the new Machinery Regulation requirements from cybersecurity to AI.
Machinery Directive vs. Machinery Regulation: All Differences Compared
Directive 2006/42/EC applies until 19 January 2027, Regulation (EU) 2023/1230 from 20 January 2027 onwards. The comparison point by point, and what it means for documentation, the declaration of conformity and the operating manual.
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