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Harmonised standards

Last reviewed: May 2026 · Legal status verified against EUR-Lex.

A harmonised standard is a European standard adopted by one of the three European standardisation organisations — CEN, CENELEC, or ETSI — on the basis of a request from the Commission, the reference of which has been published in the Official Journal of the European Union. Application of a harmonised standard produces a presumption of conformity with the essential requirements of the relevant EU harmonisation legislation that the standard is designed to cover. The presumption is rebuttable but practically decisive: products built in compliance with a harmonised standard are treated as conforming unless evidence to the contrary is produced.

Harmonised standards are not law. They are voluntary technical specifications. A manufacturer is free to demonstrate conformity by alternative means, provided it can show that the essential requirements are met. In practice, where a harmonised standard exists for a relevant essential requirement, departing from it requires a documented justification and equivalent technical evidence in the technical file.

Legal basis

How a harmonised standard comes into existence

The process under Regulation 1025/2012:

  1. Commission standardisation request (formerly called "mandate"). The Commission issues a request to CEN, CENELEC, or ETSI to develop a standard covering specified essential requirements. The request defines scope, deliverables, and deadlines.
  2. Standard drafting by a Technical Committee of the standardisation organisation, with national experts and stakeholder participation. Drafts are circulated for national member-body voting.
  3. Adoption and publication by the standardisation organisation as an EN standard (e.g., EN 60204-1, EN ISO 12100, EN 60335-1).
  4. Commission assessment against the standardisation request and the essential requirements. The Commission may accept, reject, or accept with restrictions or notes.
  5. Implementing decision published in the OJEU under Article 10(6) of Regulation 1025/2012, listing the reference of the standard with its dated edition, the act it covers, and any restrictions on the presumption of conformity.
  6. National transposition by member bodies (DIN, NF, BSI, UNI, etc.), each publishing the standard as its national version with the same dated edition.

Only after step 5 — publication of the reference in the OJEU — does the standard produce a presumption of conformity. A CEN or CENELEC EN standard whose reference has not been published in the OJEU is a voluntary standard like any other; it does not trigger the presumption.

Where to find the references

The Commission publishes consolidated lists of harmonised standards by act on its Single Market portal:

References must be checked at the time of conformity assessment — they are updated regularly. A standard withdrawn from the OJEU list ceases to confer presumption of conformity from the date specified in the withdrawing implementing decision (often after a transitional period of one to three years).

Types of harmonised standards

The standardisation community classifies standards into three types, a taxonomy formalised in the Vienna Agreement between CEN and ISO and in CENELEC Guide 414:

Type C standards take precedence over Type A and B for the products they cover, where the same hazard is addressed. Where no Type C standard exists, the manufacturer relies on Types A and B, supplemented by other technical solutions.

What the presumption of conformity covers and what it does not

The presumption is limited to the essential requirements that the harmonised standard is designed to cover. A standard may not address every essential requirement of an act applied to a product. For example, EN 60335-1 covers many but not all general safety requirements of the Low Voltage Directive 2014/35/EU; specific provisions for appliances with heating elements require EN 60335-2-XX product standards in addition.

OJEU publication may impose explicit limitations. The implementing decision for a standard often contains restrictions, such as:

These restrictions must be read alongside the standard. A manufacturer cannot claim presumption of conformity for requirements explicitly excluded by the OJEU note.

Applying a harmonised standard "in full" vs "in part"

Some acts make the choice of conformity assessment module conditional on whether harmonised standards are applied in full. The clearest example is the Machinery Regulation:

"Application in full" means every clause of the standard relevant to the product is implemented. Partial application — where the manufacturer applies some clauses and substitutes others — produces a presumption only for the clauses applied. The Declaration of Conformity must record which standards have been applied in full and which in part.

When no harmonised standard exists

For some essential requirements, no harmonised standard has been published in the OJEU. The manufacturer must then demonstrate compliance through alternative technical means and document this in the technical file. Acceptable alternatives include:

None of these confer the presumption of conformity. The burden of demonstrating compliance with the essential requirements lies entirely with the manufacturer, and the technical file must contain the supporting evidence.

Common technical specifications (CTS)

Several recent acts allow the Commission to adopt "common specifications" via implementing acts where harmonised standards are insufficient or absent. Examples: Article 9 of Regulation (EU) 2017/745 (MDR); Article 1, point 4 of Regulation (EU) 2023/2854 (the proposal known as the Data Act, not directly CE-related); the Machinery Regulation 2023/1230 (Article 19); the Radio Equipment Directive cybersecurity provisions. Common specifications produce a presumption of conformity in the same way as harmonised standards, by reference to the Commission's implementing act.

Withdrawal and revision

Standards are revised periodically by the standardisation organisations. When a new edition is published:

A product placed on the market under the predecessor edition before cessation continues to benefit from the presumption it had at the moment of placing on the market — the presumption attaches to the product at that moment, not to ongoing sales.

Common errors

Worked example

A manufacturer placing on the market a benchtop pillar drill assesses its conformity with the Machinery Regulation 2023/1230, the EMC Directive 2014/30/EU, the Low Voltage Directive 2014/35/EU (where Article 1(2)(g) of the Machinery Regulation does not absorb the LVD requirements for the specific product), and the RoHS Directive 2011/65/EU.

It applies: EN ISO 12100:2010 (Type A, general principles) for risk assessment; EN ISO 13849-1:2023 (Type B, safety-related parts of control systems) for the emergency stop and interlock; EN 61029-1 (now superseded by EN 62841-1:2015+A11:2022 for hand-held and transportable motor-operated electric tools) for the product-specific Type C requirements; EN 55014-1:2021 and EN 55014-2:2021 (EMC); EN IEC 63000:2018 (RoHS technical documentation). All references are checked against current OJEU implementing decisions for each act. Where a standard is applied in part, the deviations are documented in the technical file.

Sources

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