Harmonised Standards and Presumption of Conformity Explained

What makes a standard harmonised?

EU product laws set essential requirements in general terms. A machine must be designed so that moving parts do not cause injury. Electrical equipment must protect people against electric shock. These sentences describe a result, and standards turn them into technical solutions, test methods and limits that a design team can apply.

In the EU there are three recognised European standardisation organisations:

• CEN covers most technical fields, including machinery safety.
• CENELEC covers electrotechnical topics, such as electrical safety and electromagnetic compatibility (EMC).
• ETSI covers telecommunications and radio.

Their standards are called European standards (EN). When an EN is published, every national standards body that is a member must adopt it and withdraw conflicting national standards.

Not every European standard is harmonised. A harmonised standard follows a specific path defined by Regulation (EU) No 1025/2012 on European standardisation:

1. The European Commission sends a standardisation request to CEN, CENELEC or ETSI, linked to a specific EU law.
2. The organisation develops the standard and publishes it as an EN.
3. The Commission assesses whether the standard meets the request.
4. If the assessment is positive, the Commission publishes the reference of the standard in the Official Journal of the European Union.

Only from that publication does the standard give presumption of conformity under that law.

What does presumption of conformity cover?

If you apply a harmonised standard whose reference is published in the Official Journal, your product is presumed to conform with the essential requirements the standard covers. A market surveillance authority starts from the assumption that your product complies on those points. If it wants to challenge that, it has to show where the product falls short.

To see which requirements a standard covers, look inside it. Harmonised standards from CEN and CENELEC contain an informative annex, usually Annex ZA or Annex ZZ. ETSI standards contain a similar table, usually in Annex A. The table links clauses of the standard to the essential requirements of the law, and lists requirements that are not covered or only partly covered. Read it before you rely on a standard, and keep a copy in your technical file.

The presumption has clear limits:

• It covers only the requirements listed in that annex.
• It applies only to products inside the scope of the standard.
• If you apply only some clauses, it covers only those clauses and the requirements they relate to.

An EMC standard can give you presumption for electromagnetic compatibility. It says nothing about sharp edges, hot surfaces or noise. So most products need several standards together, and your job is to check that they leave no requirement uncovered. Where you apply a standard only in part, state which parts in the technical documentation and make this clear in the EU Declaration of Conformity.

Applying a harmonised standard does not replace your own judgement. You still check the scope, apply the standard correctly and keep the evidence. Where the law requires a risk assessment, as it does for machinery, you still carry it out.

Are harmonised standards mandatory?

Harmonised standards are voluntary. You can meet the essential requirements another way, for example with your own technical solution or another standard. The difference lies in the burden of proof. Without a harmonised standard, you must show in the technical documentation how your product meets each essential requirement. That usually means more analysis, more evidence and more questions from authorities or notified bodies.

For some products, the choice also affects the conformity assessment route. Under the Radio Equipment Directive (RED), module A is possible for the requirements of Article 3(2) and 3(3) only when covering harmonised standards are fully applied. Some machinery under Regulation (EU) 2023/1230, in Annex I Part B, can use module A only when harmonised standards or common specifications covering all relevant requirements are fully applied. Our guide on when you need a notified body explains these routes.

How to find harmonised standards in the Official Journal

The European Commission keeps a web page for each EU law in its section on harmonised standards, with a summary list for that law. It is free to consult and the most practical starting point. Open the list for the law you apply, because a standard can be harmonised under one law and not under another.

The legal source is the publication in the Official Journal. The Commission currently adopts implementing decisions, published in the L series, that add, replace or withdraw references for one law. You can find them on EUR-Lex, the official database of EU law. The summary list brings them together but may take time to be updated.

Always record the full reference of a standard: the prefix (EN, EN ISO, EN IEC), the number and part, the year of publication and any amendments (A1, A2) with their years. Two editions with the same number can be very different. A test report or declaration that quotes a standard without its year is incomplete.

Editions, cessation dates and restrictions

Each row of the summary list normally shows the reference and title of the standard and the publication where it was cited. When a new edition replaces an old one, the row also shows the superseded standard and its date of cessation of presumption of conformity. Until that date, both editions give presumption. After it, only the new one does.

Use the transition period to update your design, tests and documents. Compliance is checked for each unit when it is placed on the market. A unit shipped after the cessation date must meet the new edition, or be justified another way. Laboratories are often busy close to these dates, so plan ahead.

Sometimes the Commission cites a standard "with restrictions". This happens when part of the standard does not fully meet the essential requirements or the request. A note explains which clauses do not give presumption. The EN 18031 cybersecurity standards under the RED were cited with restrictions when first published. Restricted parts need your own solution, justified in the technical file. Read the notes, and check the latest position in the Official Journal. See our RED cybersecurity course for this case.

Standards follow the state of the art, which moves. For products you keep producing, review your standards list regularly for new editions, new citations and cessation dates, and record each review.

What to do when no harmonised standard exists

There are three typical situations. No harmonised standard exists for your product. A standard exists but covers only some requirements or hazards. Or you decide not to apply a suitable standard fully. In all three cases, you must fill the gap yourself, with one of two tools:

• Other standards: international ISO or IEC standards, EN standards not cited in the Official Journal, or recognised industry documents.
• Your own technical solution, based on engineering analysis, calculations and tests.

Justify your choice in the risk assessment, where the law requires one, and in the technical documentation. A practical method is a table with one row per essential requirement: relevance, solution adopted, and evidence with a document number. Where you did not use a harmonised standard, explain why your solution gives at least an equivalent level of protection. Our technical file guide shows how this table fits into the file.

Some newer laws, such as the Machinery Regulation and the Cyber Resilience Act, allow the Commission to adopt common specifications by implementing act. They are a fallback when harmonised standards are missing, delayed or not good enough. Like harmonised standards, they can give presumption of conformity for the requirements they cover. Check whether any exist for your law.

EN vs ISO and IEC standards: what is the difference?

Many harmonised standards are based on ISO or IEC standards and published as EN ISO or EN IEC. The international and European versions are not always identical. The European version can contain common modifications, references to other European standards and the Annex Z table. Only the European version gives presumption of conformity. If your team works from an ISO or IEC text, compare it with the EN version and read its European foreword and annexes.

National adoptions, such as UNI EN in Italy, DIN EN in Germany or NF EN in France, have the same technical content as the European standard. For presumption of conformity they are equivalent, provided the year and amendments match the edition cited.

Standards from your home market, such as UL or ANSI in the United States or GB standards in China, give no presumption of conformity in the EU. You can map that work to the EU requirements and close the gaps. IEC CB Scheme reports can be useful evidence after you check them against the EN edition currently cited and the European differences. The CE Marking Fundamentals course covers harmonised standards in its Module 3.

Key points

• A harmonised standard is an EN developed on a Commission request and cited in the Official Journal.
• Presumption of conformity covers only the requirements in the Annex Z table, for products within the scope.
• Harmonised standards are voluntary, but without them you carry the full burden of proof.
• Record the full reference with year and amendments, and watch cessation dates and restrictions.
• Only the EN version gives presumption; ISO, IEC, UL or GB versions need a gap check.