UDI Assignment under MDR Article 27 and EUDAMED Registration

The Unique Device Identification system underpins device traceability across the EU market. This article explains the UDI assignment duties under MDR Article 27, the two-level structure of Basic UDI-DI and UDI-DI, the role of issuing agencies, and the mandatory use of the EUDAMED registration module from 2026.

1. Key takeaways

Under MDR Article 27, manufacturers must assign a Unique Device Identification (UDI) to each device before it is placed on the market and place the UDI carrier on the device label and on all higher levels of packaging. The UDI consists of the UDI-DI (device identifier) and the UDI-PI (production identifier), and the Basic UDI-DI serves as the primary key and documentation index in EUDAMED. The UDI issuing agencies are designated by the Commission under Implementing Decision 2019/939.

Two further obligations frame the system. The UDI-related data must be entered into the UDI database before the device is placed on the market, and from 2026-05-28 the use of the EUDAMED UDI and device registration module becomes mandatory. In addition, specific device categories are subject to delegated regulations that refine the UDI assignment rules, so the general inference rules do not apply to them without checking the dedicated instruments first.

The assignment work should therefore be sequenced carefully: the manufacturer identifier comes first, the Basic UDI-DI grouping follows from the device group definition, and only then can the UDI-DI values be generated for individual models and versions. Reversing the sequence, for example by generating model-level identifiers before the group structure is agreed, produces identifiers that later have to be retired, and retired identifiers leave gaps in the traceability chain that are difficult to explain in an audit.

2. Legal basis

The table below lists the instruments cited in this article and their dates.

The instruments above should be read together: the MDR sets the system, the implementing decisions designate the agencies and confirm functionality, and the delegated regulations refine assignment for particular device categories.

3. Expert insights

Insight one: Basic UDI-DI and UDI-DI are two levels with different functions.

The Basic UDI-DI identifies a group of devices with the same manufacturer, the same intended purpose, and the same design and essential characteristics. It is the primary key in the EUDAMED database and the linking index for the technical documentation, the declaration of conformity and the certificates. The UDI-DI identifies the specific model or version and appears on the label. Confusing the two levels means database records can no longer be matched to physical devices, which surfaces immediately during market surveillance checks.

Insight two: the UDI carrier must appear on the label and on all higher levels of packaging.

Under Article 27(4), the UDI carrier must be placed on the label of the device and on all higher levels of packaging. This means unit packs, shipping cartons and any intermediate packaging levels each carry a readable carrier. For reusable devices, separate phased deadlines require the UDI carrier to be placed on the device itself, as covered in the dedicated article on carrier timelines in this series.

Insight three: UDI data must be registered in EUDAMED, and the module is now mandatory.

Under Article 29, manufacturers must enter the information referred to in Article 27 into the UDI database before placing a device on the market. Commission Decision (EU) 2025/2371, adopted on 2025-11-26 and published on 2025-11-27, declared the UDI database and device registration electronic system fully functional, which under Regulation (EU) 2024/1860 triggers a 6-month transition period. From 2026-05-28, use of the module is mandatory, so registration can no longer be deferred to a later phase.

Insight four: specific device categories have dedicated delegated regulations for UDI assignment.

The Commission has refined UDI assignment rules for particular categories through delegated regulations, for example Delegated Regulation (EU) 2023/2197 for contact lenses and Delegated Regulation (EU) 2025/1920 for spectacle frames and lenses. For these categories, the general inference rules of Annex VI do not apply as they otherwise would, and assignment must be checked against the dedicated instrument before Basic UDI-DI groups are created.

4. Practical recommendations

1. Obtain the manufacturer identifier from an issuing agency designated under Implementing Decision 2019/939 first, then generate the Basic UDI-DI and the UDI-DI values from it.
2. Maintain a ledger mapping each Basic UDI-DI to its device group and to the corresponding technical documentation and certificates.
3. Fix the correspondence between the label, the packaging levels and the UDI carrier forms at the design stage, to avoid tooling changes before mass production.
4. From 2026-05-28, treat EUDAMED UDI and device registration as a mandatory pre-release checkpoint for every device placed on the market.
5. For specific categories such as contact lenses and spectacle frames and lenses, verify the assignment rules against the respective delegated regulations.

Because the Basic UDI-DI is the linking index for the technical documentation, the declaration of conformity and the certificates, the ledger should be reviewed at every certificate renewal and every documentation update, so that a mismatch never reaches the database. The registration data submitted to EUDAMED should be compiled from the same ledger rather than entered independently, which keeps a single source of truth for device identification across the whole file set.

5. Verification checklist

• □ The manufacturer identifier assigned by an issuing agency has been obtained (Implementing Decision 2019/939)
• □ A Basic UDI-DI has been assigned to each device group with corresponding UDI-DI values generated
• □ UDI carriers are placed on the label and on all higher levels of packaging
• □ EUDAMED UDI / device registration status has been confirmed (mandatory from 2026-05-28)
• □ The ledger between Basic UDI-DI values and technical documentation / certificates has been established
• □ Specific categories have been checked against the delegated regulations ((EU) 2023/2197, (EU) 2025/1920)

Regulatory information verified as of 2026-10-29.

GRZAN supports medical device manufacturers entering and maintaining the EU market under Regulation (EU) 2017/745. Our team structures UDI assignment under MDR Article 27 and Annex VI, manages Basic UDI-DI ledgers, and prepares EUDAMED registration workflows for the mandatory module phase. For technical file and conformity support for the EU MDR market, contact info@grzanglobal.com.