REFERENCE / Product changes
Substantial modification: review the change, not its label
The Regulation defines a specific physical or digital change test. “Retrofit” alone does not determine the legal outcome.
The Directive remains the current framework before 20 January 2027. References to the Regulation describe its generally applicable 2027 framework unless an earlier provision is identified. This is independent educational information.
The full definition matters
Under Article 3(16), the change is made after machinery or a related product is placed on the market or put into service. It is physical or digital, is not foreseen or planned by the manufacturer and affects safety by creating a new hazard or increasing an existing risk.
That is not the end of the test. The definition additionally requires either guards or protective devices whose processing necessitates modification of the existing safety control system, or additional protective measures for stability or mechanical strength. Omitting those criteria can turn a cautious summary into an inaccurate legal rule.
Evaluate the affected system
Describe what changed, why it changed and what the manufacturer originally anticipated. Compare hazards and risk before and after the change. Examine guarding, safety-control processing, stability and strength. Keep the engineering evidence that supports each conclusion.
A software change can be relevant, as can a physical retrofit. Equally, maintenance does not automatically meet the legal definition. The assessment needs the facts of the change and the exact criteria, rather than a label supplied by the project manager.
Consequences under the Regulation
Article 18 treats the person carrying out a substantial modification as a manufacturer for the affected machinery or related product. Where only a product within an assembly is affected, the limitation must be demonstrated by the risk assessment. The relevant assessment procedure and declaration responsibilities apply.
Article 18 contains an exception for a non-professional user modifying their own machinery or related product for their own use. Do not omit that exception when explaining the manufacturer consequence, and do not extend it to professional industrial operations without basis.
Current machinery and the transition
This definition belongs to the Regulation, whose general application starts on 20 January 2027. Before then, use the current Directive framework and relevant official guidance for changes that make machinery effectively new. Workplace safety and other legislation can also matter.
A review should end with a documented conclusion, its assumptions and any required specialist assessment. This publication cannot provide a machine-specific legal determination or approve a retrofit.
Sources & related reading
- Regulation (EU) 2023/1230, consolidated 27 July 2026: Article 3(16) and Article 18.
- Directive 2006/42/EC, consolidated text: current framework.
- European Commission machinery legislation and guidance.
Continue with eu machinery law: the working framework, machinery regulation: the 2027 transition, machinery scope and product definitions.
Machine-specific interpretation and verification need competent assessment. This publication does not give legal advice or guarantee compliance.