Conformity assessment modules

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

Conformity assessment modules are the standardised procedures by which a manufacturer demonstrates that a product meets the essential requirements of the applicable EU harmonisation legislation. They are defined in Annex II of Decision No 768/2008/EC and are referenced by each sectoral directive or regulation, which selects from them according to product risk. Modules cover both the design phase (Modules B and H1) and the production phase (Modules C, D, E, F, G, H), and some modules combine the two. They are identified by single letters from A to H, with numerical sub-variants (A1, A2, C1, C2, D1, E1, F1, H1).

The choice of module is not free. Each sectoral act lists the modules available for each product category in its conformity-assessment Annex. The manufacturer may choose only among those listed, and the choice depends on the product's risk class and whether harmonised standards have been applied in full. Higher-risk products are restricted to modules involving a Notified Body; the very lowest-risk categories use Module A (self-declaration) only.

Legal basis

The modules are codified in Annex II of Decision No 768/2008/EC. The Decision itself is not directly applicable to economic operators; it is a horizontal reference instrument that sectoral acts incorporate by reference, sometimes with sector-specific adjustments. The Blue Guide 2022 (Section 5.1.2) provides the Commission's interpretation.

Three terms recur in module descriptions:

• Internal production control — the manufacturer's own quality processes verify that products conform to type or to the technical documentation.
• EU type-examination — a Notified Body examines a representative sample of the product (or its design) and certifies that it meets the essential requirements.
• Quality assurance system — a Notified Body approves the manufacturer's full or partial quality system (typically based on EN ISO 9001 with sector-specific additions).

Module A — Internal production control

Module A is the lightest module. The manufacturer:

• Establishes the technical documentation;
• Takes all measures necessary so that the manufacturing process ensures conformity of products with the documentation and with the applicable requirements;
• Affixes the CE mark and draws up the EU Declaration of Conformity.

No Notified Body is involved. The manufacturer's identification number does not appear next to the CE mark. Module A is used for: most products under the EMC Directive 2014/30/EU, most products under the Low Voltage Directive 2014/35/EU, machinery outside Annex I (formerly Annex IV) of the Machinery Regulation, and most toys complying with harmonised standards.

Modules A1 and A2

Module A1 adds supervised product testing: the manufacturer carries out tests on specific aspects of the product, but those tests are conducted by an "in-house accredited body" of the manufacturer or under the responsibility of a Notified Body. Module A2 adds supervised product checks at random intervals by a Notified Body. Both are used where the basic Module A is considered insufficient but full type-examination is not warranted — for example, parts of the Measuring Instruments Directive use A1 and A2 for utility meters.

Module B — EU type-examination

Module B is the design-phase examination. A Notified Body:

• Examines the technical documentation and supporting evidence to assess the design's conformity;
• Examines specimens of one or more critical parts of the product, or a complete product as a representative of production envisaged;
• Carries out or has carried out appropriate examinations and tests to verify that the solutions adopted meet the essential requirements;
• Issues an EU type-examination certificate if the product meets the requirements.

Module B never stands alone. It must be paired with a production-phase module: C, C1, C2, D, E, or F. The certificate has a validity defined by the Notified Body, with periodic review (commonly five years for Machinery, ten years for radio equipment).

Modules C, C1, C2 — Conformity to type based on internal production control

Module C, taken after Module B, requires the manufacturer to ensure each product conforms to the EU type-examination certificate. There is no Notified Body involvement in production under plain Module C. C1 adds product testing on specific aspects (in-house or under Notified Body responsibility). C2 adds product checks at random intervals by a Notified Body. C2 is used widely under the Measuring Instruments Directive and the Pressure Equipment Directive.

Modules D, D1 — Quality assurance of the production process

Module D is the most frequently used production-phase module after Module B. A Notified Body:

• Audits and approves the manufacturer's quality assurance system covering production, final inspection, and testing;
• Conducts periodic surveillance audits (typically annual);
• Reserves the right to unannounced visits.

The Notified Body's identification number appears next to the CE mark on every product. Module D is the standard route for high-risk machinery, Category III PPE, and a wide range of medical devices in combination with Annex IX of Regulation (EU) 2017/745. Module D1 covers products for which no Module B (type-examination) is applied — the quality system itself is the demonstration of design and production conformity, used principally where products are largely identical to existing market types.

Modules E, E1 — Product quality assurance

Module E is similar to Module D but restricted to final product inspection and testing (it does not cover the production process). The Notified Body approves and supervises the inspection and testing quality system. E1 is the equivalent of D1 — used without prior Module B, with the quality system covering design and final inspection. Module E is used principally for products where production process variability is less critical than final inspection — for example, certain pressure-equipment items and weighing instruments.

Modules F, F1 — Product verification

Module F, taken after Module B, requires a Notified Body to examine and test every product or a statistical sample to verify conformity. F1 adds the design assessment that Module B would otherwise provide (so F1 is a standalone module covering both design verification and product verification). F and F1 are used for products manufactured in small batches where unit verification is more economical than quality-system approval, for example in the Pyrotechnic Articles Directive and parts of the Marine Equipment Directive.

Module G — Unit verification

Module G is the most stringent module for one-off and very-small-series production. A Notified Body:

• Examines the design and manufacture of each individual product;
• Carries out appropriate examinations and tests to verify conformity with the essential requirements;
• Issues a certificate of conformity for each unit.

Module G is used for large pressure vessels under the Pressure Equipment Directive 2014/68/EU, certain lifts under the Lifts Directive 2014/33/EU, and one-off boilers and storage tanks. Each unit carries the Notified Body's identification number next to the CE mark.

Module H, H1 — Full quality assurance

Module H is the most comprehensive module: a Notified Body approves a full quality system covering design, production, final inspection, and testing. There is no separate type-examination; the design-control element of the quality system performs that function. The Notified Body conducts periodic surveillance audits and reserves unannounced visits. Module H is used for complex Annex I (formerly Annex IV) machinery where design diversity is high, for Class III medical devices in combination with Annex IX of Regulation (EU) 2017/745, and for many Category III items of personal protective equipment.

Module H1 adds a separate design examination by the Notified Body, resulting in an EU design-examination certificate. H1 is used for the highest-risk medical devices (Class III implantable devices) and for products where design risk warrants explicit certification beyond the design controls embedded in the quality system.

Module overview by Notified Body involvement

How sectoral acts select modules

Each sectoral act sets out, in an Annex, which modules apply to which product categories. Three patterns recur:

• Single-module acts. The Low Voltage Directive 2014/35/EU and the EMC Directive 2014/30/EU use Module A as the sole conformity assessment route for almost all in-scope products. No Notified Body is involved.
• Risk-class-based selection. The PPE Regulation 2016/425 assigns Category I PPE to Module A, Category II to Module B + C, and Category III to Module B + C2, D, or E. The Medical Devices Regulation 2017/745 assigns module combinations by Class (I, IIa, IIb, III) under Articles 52 and 53 and Annexes IX–XI.
• Annex-based selection. The Machinery Regulation 2023/1230 lists certain product categories in Annex I (formerly Annex IV under Directive 2006/42/EC). For Annex I machinery, conformity assessment by a Notified Body is required unless harmonised standards have been applied in full covering all essential requirements. For all other machinery, Module A is sufficient.

Choosing among modules: practical criteria

Where an act offers more than one module for a product category, the manufacturer's choice is shaped by:

• Production volume. Module G (unit verification) is economical only for one-off and very-small-series production. Modules D and H are economical only where annual volumes justify ongoing quality-system audits.
• Existing quality system. A manufacturer already certified to EN ISO 9001 or EN ISO 13485 incurs much lower marginal cost in adding a Notified Body to that system (Modules D, E, H) than in switching to unit verification.
• Design variability. Where design is largely stable, Module B + C2 keeps Notified Body involvement to type-examination and periodic checks. Where design varies frequently, Module H (no separate B) avoids repeated type-examinations.
• Notified Body availability. For medical devices and machinery, queue times at Notified Bodies have been a constraint since 2021. Module choice and Notified Body selection often interact.

Common errors

• Selecting a module the sectoral act does not allow. Module A cannot be used for Annex I machinery; Module H cannot be used under the Low Voltage Directive. The act's conformity-assessment Annex is binding.
• Module B without a production-phase module. Module B alone is not a complete conformity assessment. The EU type-examination certificate must be paired with C, C1, C2, D, E, or F before the CE mark is affixed.
• Adding the Notified Body number under Module A. No Notified Body is involved in plain Module A. Adding a four-digit number next to the CE mark misrepresents the assessment route and is itself an infringement (Article 30(2) of Regulation 765/2008).
• Not updating the Notified Body when scope changes. A Notified Body's designation under Regulation (EU) 2019/1020 is limited to specific acts and product ranges in the NANDO database. Adding a new product range may require re-engaging or changing the Notified Body.
• Treating "type-examination certificate" as the CE mark. The certificate is issued by the Notified Body for Module B. The CE mark is affixed by the manufacturer after the production-phase module is complete and the EU Declaration of Conformity is drawn up.

Relationship to harmonised standards

Several sectoral acts make the choice of module conditional on whether harmonised standards have been applied in full. Under Article 22(2) of the Machinery Regulation, for Annex I machinery, Module A is available if all essential requirements are covered by harmonised standards published in the OJEU and those standards have been applied in full. If they have not, the manufacturer must use Modules B + C, D, E, F, G, or H. The presumption of conformity attaching to harmonised standards thus directly determines the regulatory burden.

Sources

• Decision No 768/2008/EC, Annex II — EUR-Lex.
• Regulation (EC) No 765/2008, Article 30 — EUR-Lex.
• Commission Notice — Blue Guide 2022, Section 5 — EUR-Lex.
• NANDO database of Notified Bodies — European Commission.
• Regulation (EU) 2023/1230, Annex XI (conformity assessment procedures for machinery) — EUR-Lex.