UDI for Medical Devices: Unique Device Identification in the EU and US, Including EUDAMED

Unique Device Identification (UDI) lets a device be identified through distribution and use, which makes recalls faster, adverse event reports more precise and patient safety data more useful. Both the US and the EU have UDI systems, and they are similar in idea but different in detail. This guide explains the structure of a UDI, what each system requires, and the practical steps for implementation, including a near-term EUDAMED deadline.

What a UDI is made of

A UDI has two parts:

• Device identifier (UDI-DI): a fixed code identifying the manufacturer and the specific device version or model, including each packaging level.
• Production identifier (UDI-PI): variable information such as lot or batch number, serial number, manufacturing date, expiry date and, in some cases, software version.

The UDI must appear on the label and packaging in two forms: easily readable plain text and machine-readable AIDC (automatic identification and data capture) such as a barcode or data matrix. Some devices, such as reusable devices that are reprocessed between uses, also need the UDI marked directly on the device.

Issuing agencies and standards

You do not make up your own code. UDI-DIs are created using the format of an accredited issuing agency such as GS1, HIBCC or ICCBBA, plus other agencies designated in each jurisdiction. Choose one that your customers, such as hospitals and distributors, already use, and keep to one system across your range where possible.

United States: 21 CFR Part 830 and Part 801

• Labellers put a UDI on device labels and packages, unless an exception applies (for example certain class I devices, single-use devices that are all stored together, and others).
• Data about each device version is submitted to FDA’s Global Unique Device Identification Database (GUDID), which is public through AccessGUDID.
• Direct marking is required for devices intended for more than one use and reprocessed before each use.
• Dates on labels follow a standard format, and the rules set what counts as a new version needing a new DI.
• The compliance dates were phased by device class, and have now passed for most categories. Check the current status of any exceptions that you rely on.

For how UDI fits with US regulatory requirements overall, see US FDA medical device regulations.

European Union: MDR Article 27 and Annex VI

The EU system has an extra layer:

• Basic UDI-DI: the main key in the database. It groups devices with the same intended purpose, risk class and essential design and manufacturing characteristics. It does not appear on the label but it appears in certificates, declarations of conformity and the summary of safety and clinical performance.
• UDI-DI and UDI-PI are on the label as in the US.
• Manufacturers assign UDIs, and register devices in the UDI/Device module of EUDAMED. Registration is part of placing the device on the market.
• Implants and other devices have to meet UDI labelling deadlines that were staggered by risk class, and you should check the current deadlines for your class.

EUDAMED: what changed in 2026

The first four EUDAMED modules (actor registration, UDI/device registration, notified bodies and certificates, and market surveillance) became mandatory on 28 May 2026. New devices must be registered in the UDI/Device module before the first unit is placed on the market. Devices already on the market before that date, including legacy devices, that continue to be sold must be registered by a transition deadline in late November 2026, which is twelve months after the Commission’s notice (the Commission’s timeline gives 28 November 2026; some sources cite 27 November). Legacy devices that are no longer sold need not be registered unless a vigilance or surveillance action arises. Legacy devices have no Basic UDI-DI, so EUDAMED uses its own identifiers for them. Confirm exact dates and rules on the Commission’s EUDAMED pages, as the rollout is still evolving, with the vigilance and clinical investigation modules still to follow.

Check your actor registration and single registration number (SRN) first; without them, no device can be registered. For the wider regulatory picture, see EU MDR and IVDR explained.

A practical implementation plan

1. Inventory your products. List every model, variant, size and packaging level, including kits and systems.
2. Write the DI assignment rules. Decide what change triggers a new UDI-DI (for example a change in a clinical size, sterility, labelling language where it affects the device, or a significant change in a packaging configuration).
3. Define the data elements. Agree ownership between regulatory affairs, quality, supply chain and IT for each field, such as the device description, risk class, MRI safety status, sterile status and storage conditions.
4. Design the label and verify it. Test barcode quality (grading) and readability, and verify that human-readable and machine-readable data match. Treat label changes through design controls and change control.
5. Register devices. Submit to GUDID and EUDAMED, and keep the records synchronised with the master data.
6. Link UDI to quality processes. Include UDI in complaint records, vigilance reports, field safety actions and the CAPA and complaint handling process, so that you can trace affected units quickly.
7. Maintain it. Assign an owner for updates when a device or label changes, and review periodically.

Common mistakes

• Changing a label or a device without checking whether a new UDI-DI is needed.
• Mismatched data between the label, GUDID or EUDAMED and the ERP system.
• Poor barcode print quality, so scanners cannot read the code.
• Not including packaging levels such as boxes and cartons.
• No procedure for UDI changes, leaving updates to chance.
• Assuming that US UDI compliance means EU compliance. The structures differ, notably the Basic UDI-DI.

Frequently asked questions

Does UDI apply to custom-made devices?

Custom-made and investigational devices are outside the normal UDI registration scheme in the EU, though other labelling rules apply. Check the rules for your category.

What is the difference between UDI-DI and Basic UDI-DI?

The UDI-DI identifies a specific version and packaging level and appears on the label. The Basic UDI-DI is the EU-only grouping key used in the database and in regulatory documents.

Can I use more than one issuing agency?

Yes, but it adds complexity. Most manufacturers pick one agency for consistency and add another only for market-specific reasons.

Who is responsible for UDI data accuracy?

The manufacturer. Distributors, importers and authorised representatives have their own verification duties, but the data you submit is your responsibility.

Talk to the AptSkill team

Need UDI or EUDAMED training for your regulatory and labelling teams? Send us a message.