---
title: "When does used or modified machinery need a new conformity assessment?"
canonical_url: "https://www.sorena.io/artifacts/eu/machinery-regulation/faq/used-and-modified-machinery"
source_url: "https://www.sorena.io/artifacts/eu/machinery-regulation/faq/used-and-modified-machinery"
author: "Sorena AI"
description: "FAQ on used and modified machinery under Regulation (EU) 2023/1230, including substantial modification, first EU use, technical documentation, and market surveillance evidence."
published_at: "2026-05-09"
updated_at: "2026-05-09"
keywords:
  - "Regulation (EU) 2023/1230"
  - "used machinery"
  - "modified machinery"
  - "substantial modification"
  - "machinery conformity assessment"
  - "market surveillance"
  - "EU Machinery Regulation"
---
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# When does used or modified machinery need a new conformity assessment?

FAQ on used and modified machinery under Regulation (EU) 2023/1230, including substantial modification, first EU use, technical documentation, and market surveillance evidence.

*FAQ* *EU*

## Used and modified machinery conformity assessment FAQ

Used machinery does not need a new EU Machinery Regulation assessment just because ownership changes. The trigger is the legal boundary: first EU placing on the market or putting into service, or a later substantial modification that creates a new hazard or increases an existing risk.

Use this page to separate resale, first EU use, repairs, planned upgrades, and substantial modifications before updating technical documentation or issuing a new declaration.

Used or modified machinery needs a new Regulation (EU) 2023/1230 conformity assessment when the event is a first placing on the EU market, a first putting into service in the EU, or a substantial modification after the machinery or related product has already been placed on the market or put into service. A substantial modification is not every repair or retrofit: it is an unplanned physical or digital modification that affects safety by creating a new hazard or increasing an existing risk and requires new guards, protective devices tied to the safety control system, or additional protective measures for stability or mechanical strength.

## What is the short answer for used machinery?

Start with the market boundary. Regulation (EU) 2023/1230 defines placing on the market as the first making available of an in-scope product on the Union market, and putting into service as the first use in the Union for its intended purpose. A second-hand machine that was already lawfully placed on the EU market is not automatically treated as newly placed on the market just because it is sold again.

The answer changes when the machine is first brought into EU use after being used outside the EU, or when a later modification crosses the substantial-modification test. In those cases, the team should treat the event as a conformity trigger instead of relying on the old declaration, old technical file, or a resale record alone.

- For EU-origin used machinery, confirm whether the item was already placed on the EU market or put into service and whether the planned work is repair, maintenance, a manufacturer-planned update, or a substantial modification.
- For machinery first moved into the EU after earlier use outside the EU, assess first EU putting into service before production use.
- For modified machinery, test the modification against the Regulation's substantial-modification definition before deciding whether a new conformity assessment is required.

Sources for this answer:

- [Regulation (EU) 2023/1230 on machinery](https://eur-lex.europa.eu/eli/reg/2023/1230/oj?ref=sorena.io) - Defines placing on the market, putting into service, and substantial modification for machinery and related products.
- [Guide to application of the Machinery Directive 2006/42/EC](https://ec.europa.eu/docsroom/documents/60145?ref=sorena.io) - Grounds the used-machinery distinction between first EU use and existing EU machinery under the prior machinery regime.

## How to test whether a modification is substantial

Apply the substantial-modification test in sequence. The modification must occur after placing on the market or putting into service; be physical or digital; be outside what the manufacturer foresaw or planned; affect safety by creating a new hazard or increasing an existing risk; and require either guards or protective devices that change the existing safety control system, or additional protective measures for stability or mechanical strength.

Repairs and maintenance that do not affect compliance with the essential health and safety requirements should not be treated as substantial modifications. Planned manufacturer updates are also different from an unplanned third-party modification because the definition requires the change not to be foreseen or planned by the manufacturer.

- Record the before-and-after intended use, operating envelope, safety functions, guards, protective devices, control-system logic, software version, stability assumptions, and mechanical-strength assumptions.
- Map each new or increased risk to the essential health and safety requirement it affects and to the protective measure selected.
- If only one machine in an assembly is affected, keep the risk assessment tight enough to show why the new conformity work is limited to that affected machinery or related product.

Sources for this answer:

- [Regulation (EU) 2023/1230 on machinery](https://eur-lex.europa.eu/eli/reg/2023/1230/oj?ref=sorena.io) - Provides the substantial-modification definition and Article 18 obligations for the person carrying out the modification.
- [ISO 12100:2010 safety of machinery](https://www.iso.org/obp/ui/en/?ref=sorena.io#!iso:std:51528:en) - Supports using documented hazard identification, risk estimation, risk evaluation, risk reduction, and verification when reassessing machinery changes.

## What changes when the answer is yes?

If the event is first EU placing on the market, first EU putting into service, or a substantial modification by a professional operator, the responsible person cannot simply annotate the old file. For machinery and related products, Article 10 requires design and construction in line with Annex III, technical documentation under Annex IV Part A, the relevant Article 25 conformity assessment procedure, an EU declaration of conformity, CE marking, instructions, and retention of the technical documentation and declaration for market surveillance authorities.

For partly completed machinery, the evidence route is different: Article 11 points to Annex IV Part B technical documentation, an EU declaration of incorporation, and assembly instructions. Do not replace that with a machinery declaration unless the product has become complete machinery or a related product.

- Update the technical documentation, risk assessment, drawings, calculations, test records, standards mapping, safety-control evidence, software or programming-logic evidence where relevant, instructions, and declaration affected by the change.
- Use Article 25 to select the procedure: Annex I Part A categories require notified-body routes; Annex I Part B categories can use internal production control only when the applicable harmonised standards or common specifications cover all relevant essential health and safety requirements; non-Annex I machinery uses module A.
- Keep the old evidence linked but clearly mark what remains valid, what was superseded, and what was newly assessed for the modified configuration.

Sources for this answer:

- [Regulation (EU) 2023/1230 on machinery](https://eur-lex.europa.eu/eli/reg/2023/1230/oj?ref=sorena.io) - Articles 10, 11, 18, and 25 ground the manufacturer obligations, partly completed machinery evidence, substantial-modification responsibility, and conformity assessment choices.
- [European Commission - harmonised standards overview](https://single-market-economy.ec.europa.eu/single-market/goods/european-standards/harmonised-standards_en?ref=sorena.io) - Explains the role of harmonised standards in supporting presumption of conformity under EU product rules.

## What evidence should market surveillance be able to follow?

The record should let a market surveillance authority or decision owner see why the machine was treated as resale, first EU use, ordinary repair, planned update, or substantial modification. The evidence should not be a generic compliance statement; it should tie the actual modification to the legal test and the updated risk assessment.

Regulation (EU) 2023/1230 requires manufacturers to keep technical documentation and declarations available to market surveillance authorities for at least 10 years after machinery is placed on the market or put into service. Regulation (EU) 2019/1020 gives market surveillance authorities powers to require corrective action and, where risks persist, restrict, withdraw, or recall products.

- Keep the original declaration, instructions, serial or type identification, import or resale documents, and evidence of first EU placing on the market or first EU putting into service.
- For modifications, keep a dated change description, substantial-modification analysis, risk assessment, affected EHSRs, standards or specifications used, tests, safety-control verification, software version evidence, updated instructions, declaration, and CE-marking decision.
- For authority readiness, keep the accountable economic operator, customer or site location, corrective-action log, complaint or incident links, and the file index showing where technical documentation can be made available.

Sources for this answer:

- [Regulation (EU) 2023/1230 on machinery](https://eur-lex.europa.eu/eli/reg/2023/1230/oj?ref=sorena.io) - Grounds the technical documentation, declaration retention, authority cooperation, and product-withdrawal or recall hooks under the Machinery Regulation.
- [Regulation (EU) 2019/1020 on market surveillance](https://eur-lex.europa.eu/eli/reg/2019/1020/oj?ref=sorena.io) - Grounds market surveillance checks, corrective-action powers, restrictions, withdrawal, and recall for products on the Union market.

## Common mistakes in used and modified machinery decisions

Most errors come from skipping the boundary question. A team treats a used machine as automatically exempt, or treats every repair as a new machine, without documenting first EU use, the manufacturer's planned configuration, and whether the modification actually creates a new hazard or increases an existing risk.

The other frequent problem is evidence drift: the old declaration, old test report, or supplier file may still matter, but it does not prove the modified configuration unless the changed hazards, safety functions, instructions, and conformity route have been reassessed.

- Do not call a change non-substantial without checking both safety impact and the protective measures required by the Regulation's definition.
- Do not use a declaration for partly completed machinery as if it were a declaration of conformity for complete machinery.
- Do not ignore digital changes: software, safety components, control logic, and cybersecurity-related safety effects can be part of the modification analysis.

Sources for this answer:

- [Regulation (EU) 2023/1230 on machinery](https://eur-lex.europa.eu/eli/reg/2023/1230/oj?ref=sorena.io) - Grounds the distinction between machinery, related products, partly completed machinery, safety components, software, and substantial modifications.
- [ISO/TR 22100-4:2018 safety of machinery and IT-security](https://www.iso.org/standard/73335.html?ref=sorena.io) - Supports considering IT-security threats where they can influence machinery safety during placing on the market or putting into service.

## Primary sources

- [Regulation (EU) 2023/1230 on machinery](https://eur-lex.europa.eu/eli/reg/2023/1230/oj?ref=sorena.io) - Primary source for scope, placing on the market, putting into service, substantial modification, Article 18 responsibility, technical documentation, conformity assessment, and market surveillance hooks.
  - Quote: "substantial modification"
- [Regulation (EU) 2019/1020 on market surveillance](https://eur-lex.europa.eu/eli/reg/2019/1020/oj?ref=sorena.io) - Grounds EU market surveillance checks, corrective-action powers, restrictions, withdrawal, and recall for products on the Union market.
  - Quote: "market surveillance"
- [Guide to application of the Machinery Directive 2006/42/EC](https://ec.europa.eu/docsroom/documents/60145?ref=sorena.io) - Used only for the grounded distinction between existing used machinery, first EU putting into service, and modifications under the prior machinery regime.
  - Quote: "new and used machinery"
- [European Commission - harmonised standards overview](https://single-market-economy.ec.europa.eu/single-market/goods/european-standards/harmonised-standards_en?ref=sorena.io) - Supports the explanation that harmonised standards can support presumption of conformity where they cover relevant requirements.
  - Quote: "Harmonised standards"
- [ISO 12100:2010 safety of machinery](https://www.iso.org/obp/ui/en/?ref=sorena.io#!iso:std:51528:en) - Supports the risk assessment and risk reduction evidence expected when reassessing modified machinery.
  - Quote: "risk assessment and risk reduction"
- [ISO/TR 22100-4:2018 safety of machinery and IT-security](https://www.iso.org/standard/73335.html?ref=sorena.io) - Supports consideration of IT-security threats where they can influence machinery safety.
  - Quote: "IT-security threats"

## Topic Guides

- [Declaration of Conformity vs Declaration of Incorporation | Machinery Regulation FAQ](/artifacts/eu/machinery-regulation/faq/doc-and-doi.md): FAQ on when machinery needs an EU Declaration of Conformity and when partly completed machinery needs an EU Declaration of Incorporation under Regulation (EU) 2023/1230.
- [Directive 2006/42/EC to Machinery Regulation transition](/artifacts/eu/machinery-regulation/transition-from-directive-2006-42-ec.md): Transition guide for moving EU machinery files from Directive 2006/42/EC to Regulation (EU) 2023/1230, focused on the 20 January 2027 changeover, pipeline products, declarations, standards, technical documentation, software, cybersecurity, and digital instructions.
- [EU Machinery Regulation Applicability Test](/artifacts/eu/machinery-regulation/applicability-test.md): Test whether a product is machinery, a related product, partly completed machinery, a safety component, substantially modified, excluded, or covered by overlapping EU product laws.
- [EU Machinery Regulation compliance](/artifacts/eu/machinery-regulation/compliance.md): Machinery Regulation compliance checklist covering scope, EHSR risk assessment, technical documentation, instructions, conformity assessment, EU declarations, CE marking, software, transition, and market surveillance.
- [EU Machinery Regulation compliance checklist](/artifacts/eu/machinery-regulation/checklist.md): Checklist for Regulation (EU) 2023/1230 covering scope, EHSR risk assessment, technical documentation, instructions, conformity assessment, EU declarations, CE marking, digital duties, transition, and market surveillance.
- [EU Machinery Regulation deadlines and compliance calendar](/artifacts/eu/machinery-regulation/deadlines-and-compliance-calendar.md): Calendar for Regulation (EU) 2023/1230 dates, Directive 2006/42/EC transition, release documentation gates, standards monitoring, and substantial-modification reviews.
- [EU Machinery Regulation FAQ](/artifacts/eu/machinery-regulation/faq.md): Answers to Machinery Regulation questions on scope, partly completed machinery, Annex I categories, Article 25 conformity assessment, digital instructions, software, cybersecurity, transition, CE files, and overlap with other EU product laws.
- [EU Machinery Regulation Partly Completed Machinery](/artifacts/eu/machinery-regulation/partly-completed-machinery.md): What counts as partly completed machinery under Regulation (EU) 2023/1230, what documents travel with it, and where the final assembler takes over.
- [EU Machinery Regulation requirements](/artifacts/eu/machinery-regulation/requirements.md): Requirements under Regulation (EU) 2023/1230: machinery scope, EHSR risk assessment, technical documentation, instructions, conformity assessment, EU declaration, CE marking, software evidence, transition, and surveillance.
- [EU Machinery Regulation Safety Components](/artifacts/eu/machinery-regulation/safety-components.md): Definition, scope, conformity assessment, technical documentation, declaration, CE marking, and grounded examples for safety components under Regulation (EU) 2023/1230.
- [EU Machinery Regulation scope and machine categories](/artifacts/eu/machinery-regulation/scope-and-machine-categories.md): Scope guide for Regulation (EU) 2023/1230 covering machinery, related products, partly completed machinery, Annex I categories, exclusions, substantial modification, and category evidence.
- [EU Machinery Regulation substantial modification decision workflow](/artifacts/eu/machinery-regulation/substantial-modification-workflow.md): Workflow for assessing substantial modification under Regulation (EU) 2023/1230: change facts, hazard and risk impact, manufacturer obligations, conformity assessment, CE marking, and evidence.
- [EU Machinery Regulation vs LVD](/artifacts/eu/machinery-regulation/machinery-vs-lvd.md): Compare the EU Machinery Regulation and Low Voltage Directive boundary for machinery EHSRs, electrical risks, excluded electrical products, CE documentation, and evidence reuse.
- [EU Machinery Regulation vs Market Surveillance Regulation: compliance comparison](/artifacts/eu/machinery-regulation/machinery-vs-msr.md): Compare Machinery Regulation product compliance duties with EU MSR market surveillance duties, authority requests, online sales, corrective action and evidence records.
- [EU Machinery Regulation: autonomous mobile and collaborative machinery](/artifacts/eu/machinery-regulation/autonomous-mobile-and-collaborative-machinery.md): Grounded guide to Regulation (EU) 2023/1230 requirements for autonomous mobile machinery, human-machine interaction, controls, software, cybersecurity, risk assessment, technical documentation, and conformity routes.
- [EU Machinery Regulation: when does a modification constitute substantial modification?](/artifacts/eu/machinery-regulation/substantial-modification.md): Guide to substantial modification under Regulation (EU) 2023/1230: change triggers, risk assessment, EHSRs, technical documentation, conformity assessment, CE marking, and records.
- [EU Machinery Risk Assessment Method](/artifacts/eu/machinery-regulation/risk-assessment-method.md): How to document an EU Machinery Regulation risk assessment: ISO 12100 hazard identification, EHSR mapping, risk reduction, residual risk, software, cybersecurity, and technical-file evidence.
- [How to map Annex III EHSRs under the EU Machinery Regulation | Machinery Regulation FAQ](/artifacts/eu/machinery-regulation/faq/annex-iii-ehsr.md): FAQ on mapping Annex III essential health and safety requirements to hazards, risk reduction, software controls, technical documentation, and Annex I classification under Regulation (EU) 2023/1230.
- [Machinery CE documentation template for Regulation (EU) 2023/1230](/artifacts/eu/machinery-regulation/machinery-ce-documentation-template.md): Template fields for Machinery Regulation CE documentation: product identity, scope, EHSR risk assessment, standards, tests, instructions, EU declaration, CE marking, notified body route, software, cyber, and substantial modification checks.
- [Machinery Regulation and EU AI Act overlap for AI-enabled safety functions](/artifacts/eu/machinery-regulation/faq/ai-act-overlap.md): FAQ on Machinery Regulation overlap with the EU AI Act for self-evolving or machine-learning safety functions, Annex I categories, standards work, and technical documentation boundaries.
- [Machinery Regulation Annex I conformity route workflow](/artifacts/eu/machinery-regulation/annex-i-route-workflow.md): Classify machinery against Annex I Part A and Part B, choose the Article 25 conformity assessment route, and assemble the technical evidence file.
- [Machinery Regulation Annex I high-risk categories](/artifacts/eu/machinery-regulation/annex-i-and-high-risk-machinery.md): Explain what Annex I does under Regulation (EU) 2023/1230, which listed machinery categories trigger special conformity routes, and what evidence to keep.
- [Machinery Regulation category and scope checks](/artifacts/eu/machinery-regulation/category-and-scope-workflow.md): Check whether a product is machinery, a related product, partly completed machinery, a safety component, excluded from scope, or listed in Annex I under Regulation (EU) 2023/1230.
- [Machinery Regulation conformity assessment and CE marking](/artifacts/eu/machinery-regulation/conformity-assessment-and-ce.md): EU Machinery Regulation guide to Article 25 conformity assessment routes, Annex I machinery categories, technical documentation, EU declarations, CE marking, and instructions.
- [Machinery Regulation cybersecurity evidence FAQ](/artifacts/eu/machinery-regulation/faq/cybersecurity.md): What cybersecurity evidence connected or software-enabled machinery should keep for protection against corruption, safety-related control systems, and machinery risk assessment.
- [Machinery Regulation digital instructions](/artifacts/eu/machinery-regulation/digital-instructions.md): EU Machinery Regulation guide to digital instructions for use: access marking, print and download access, paper copies, non-professional safety information, languages, and records.
- [Machinery Regulation penalties and enforcement](/artifacts/eu/machinery-regulation/penalties-and-fines.md): EU Machinery Regulation enforcement guide covering Member State penalty rules, corrective action, market surveillance powers, and cross-border authority cooperation.
- [Machinery Regulation related products scope guide](/artifacts/eu/machinery-regulation/related-products.md): Classify EU Machinery Regulation related products, including interchangeable equipment, safety components, lifting accessories, lifting chains, ropes, webbing, and removable transmission devices.
- [Machinery Regulation software and cybersecurity considerations](/artifacts/eu/machinery-regulation/software-and-cybersecurity-considerations.md): How Regulation (EU) 2023/1230 treats safety-related software, control systems, corruption protection, technical documentation, and cyber-safety risk evidence.
- [Machinery Regulation Technical Documentation and Technical File](/artifacts/eu/machinery-regulation/technical-documentation-and-technical-file.md): What to keep in the EU Machinery Regulation technical file: product identification, risk assessment, EHSR mapping, standards, tests, instructions, declarations, software evidence, retention, and notified-body records.
- [Machinery Regulation technical file acceptance workflow](/artifacts/eu/machinery-regulation/technical-file-acceptance-workflow.md): Release-gate workflow for accepting an EU Machinery Regulation technical file: scope, EHSR risk evidence, standards, tests, declarations, notified-body records, software, cyber, and signoff.
- [Machinery Regulation Timeline and Transition: practical guide](/artifacts/eu/machinery-regulation/timeline-and-transition.md): EU Machinery Regulation guide to Timeline and Transition with scope decisions, owner actions, evidence records, source-linked citations, and practical next steps.
- [Machinery Regulation vs EMC Directive](/artifacts/eu/machinery-regulation/machinery-vs-emc.md): Compare EU machinery safety duties with EMC duties for equipment, CE documentation, harmonised standards, declarations, and combined technical files.
- [Machinery Regulation vs EU AI Act: machinery safety overlap](/artifacts/eu/machinery-regulation/machinery-regulation-vs-eu-ai-act.md): A grounded comparison of the EU Machinery Regulation and EU AI Act for machinery with AI-enabled safety functions, software, cyber-safety and technical documentation overlap.
- [Machinery Regulation vs Machinery Directive](/artifacts/eu/machinery-regulation/machinery-regulation-vs-machinery-directive.md): Grounded comparison of Regulation (EU) 2023/1230 and Directive 2006/42/EC across legal form, timing, scope, digital instructions, cybersecurity, conformity assessment, documentation, and CE marking.
- [Machinery vs RED comparison](/artifacts/eu/machinery-regulation/machinery-vs-red.md): Compare EU Machinery Regulation and Radio Equipment Directive boundaries for machinery safety, radio equipment scope, CE documentation, and shared evidence.
- [What counts as machinery under Regulation (EU) 2023/1230?](/artifacts/eu/machinery-regulation/faq/machinery-definition.md): FAQ on the Machinery Regulation definition of machinery, including assemblies, drive systems, missing components, software, related products, partly completed machinery, safety components, and exclusions.
- [When can a software update affect Machinery Regulation compliance?](/artifacts/eu/machinery-regulation/faq/software-updates.md): FAQ on when machinery software updates can trigger Machinery Regulation review, including safety functions, substantial modification, corruption protection, instructions, and CE technical-file evidence.
- [When is a notified body needed under the EU Machinery Regulation?](/artifacts/eu/machinery-regulation/faq/notified-bodies.md): FAQ on when Machinery Regulation Annex I products need a notified body, how to find designated bodies, and what manufacturers still own.
- [Which Article 25 conformity assessment module applies? | EU Machinery Regulation FAQ](/artifacts/eu/machinery-regulation/faq/article-25-modules.md): FAQ on Article 25 of Regulation (EU) 2023/1230: Module A, Module B plus C, Module H, Module G, Annex I triggers, notified body involvement, and technical file evidence.

*Recommended next step*

*Placement: after evidence section*

## Review the modified-machine evidence before release

Use the substantial-modification test, risk assessment, technical documentation, and declaration trail to decide whether the modified configuration is ready for EU placing on the market or putting into service.

- [Open Research Copilot](/solutions/research-copilot.md): Check Machinery Regulation scope, substantial modification, and conformity assessment questions with cited outputs.
- [Talk through implementation](/contact.md): Review your modification facts, risk assessment, technical file updates, and authority-response evidence.


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