Conformity assessment modules

Last reviewed: October 2026 · Sources listed at the end of this page.

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. Module B covers the design phase, Modules C, D, E and F the production phase, and Modules A, G and H both. 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, so no Notified Body identification number appears 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 toys where harmonised standards cover all relevant safety requirements.

Modules A1 and A2

Module A1 adds supervised product testing: tests on specific aspects of the product are carried out by an accredited in-house body or under the responsibility of a Notified Body. Module A2 adds supervised product checks at random intervals, by an accredited in-house body or a Notified Body. Both sit between basic Module A and full type-examination. A1 appears in the Recreational Craft Directive 2013/53/EU; A2 appears in the Measuring Instruments Directive 2014/32/EU and the Pressure Equipment Directive 2014/68/EU. Where a Notified Body does the work, its number is affixed; an accredited in-house body has no such number.

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. Certificate validity differs by act: a maximum of five years under the Machinery Regulation (Annex VII) and the PPE Regulation, ten years, renewable, under the Pressure Equipment Directive, and no fixed period under the Radio Equipment Directive.

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. As a general rule there is no Notified Body involvement in production under plain Module C. C1 adds product testing on specific aspects (by an accredited in-house body or under Notified Body responsibility). C2 adds product checks at random intervals (by an accredited in-house body or a Notified Body). C2 appears, for example, in the Measuring Instruments, Pressure Equipment, PPE and Pyrotechnic Articles acts; C1 in the ATEX and Simple Pressure Vessels Directives.

Modules D, D1 — Quality assurance of the production process

Under Module D, which follows Module B, a Notified Body:

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

The Notified Body's identification number appears next to the CE mark on every product. Module D is a standard route for Category III PPE (as the alternative to Module B + C2); the Medical Devices Regulation contains an equivalent production quality assurance procedure in Annex XI, Part A. The Machinery Regulation does not offer Module D. Module D1 is used without Module B: the manufacturer draws up the technical documentation itself and the Notified Body approves and surveys the production quality system, but does not examine the design.

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 manufacturer drawing up the technical documentation and the quality system covering final inspection and testing. Module E appears, for example, in the Pressure Equipment, Measuring Instruments and Marine Equipment Directives.

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 is used without Module B: the manufacturer draws up the technical documentation and a Notified Body verifies the products against it. Module F appears, for example, in the Non-Automatic Weighing Instruments and Marine Equipment Directives; F1 in the Non-Automatic Weighing Instruments and Measuring Instruments Directives.

Module G — Unit verification

Module G suits 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 appears, for example, in the Pressure Equipment Directive 2014/68/EU, the Lifts Directive 2014/33/EU, the Pyrotechnic Articles Directive, and the Machinery Regulation. 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 one of the routes for Annex I (formerly Annex IV) machinery, and the Medical Devices Regulation's quality management system procedure (Annex IX of Regulation (EU) 2017/745) follows similar logic.

Module H1 adds a separate design examination by the Notified Body, resulting in an EU design-examination certificate. H1 appears, for example, in the Pressure Equipment and Measuring Instruments Directives.

Module overview by Notified Body involvement

The table states the general rule in Article R12(3) of Decision 768/2008/EC and the Blue Guide (section 4.5.1.5). Always check the act: Article 24(3) of the Machinery Regulation requires the number whenever module B + C, H or G is used, and Article 20(3) of the Radio Equipment Directive requires it only under Annex IV (Module H).

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 rely on Module A: it is the sole route under the Low Voltage Directive, while the EMC Directive (Article 14) also offers Module B + C. No Notified Body is involved under Module A.
• 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 or Module B + D (Article 19). 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 the six Part A categories of Annex I, a Notified Body is always required (Module B + C, H, or G). For the 19 Part B categories, Module A is available only where the machinery is designed and built to harmonised standards or common specifications covering all relevant 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 running a quality system to EN ISO 9001 or EN ISO 13485 has a head start on the quality-assurance modules (D, E, H), though that certification does not replace the Notified Body's approval.
• 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. Not every body is notified for every module; check NANDO before settling on a route.

Common errors

• Selecting a module the sectoral act does not allow. Module A cannot be used for Annex I Part A 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.
• Not updating the Notified Body when scope changes. A Notified Body's notification under each sectoral act 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 25(3) of the Machinery Regulation, for Annex I Part B machinery, Module A is available if the machinery is designed and built to harmonised standards or common specifications covering all relevant essential requirements. If not, the manufacturer must use Module B + C, Module H, or Module G. The availability of cited standards therefore decides whether a Notified Body is needed; see the current status of machinery citations.

Frequently asked questions

What is Module A?

Internal production control. The manufacturer compiles the technical documentation, controls production, affixes the CE mark and signs the declaration, with no Notified Body involved.

Can I choose any module I like?

No. You may choose only among those the applicable act lists for your product category.

Why does a CE mark sometimes have no four-digit number even though a Notified Body issued a certificate?

As a general rule the number shows involvement in production control, not design. Module B + C therefore usually leaves no number, although the Machinery Regulation is an exception. Check a number with the CE number lookup.

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, Article 25 and Annexes VI–X (conformity assessment procedures for machinery) — EUR-Lex.