Page Last Reviewed: 13 January 2026

While Basic UDI-DI was created to help streamline device identification, it continues to be a confusing concept to many. Even though MDCG guidance document 2018-1 Rev.4 has been published on Basic UDI-DI, it still leaves a lot unanswered. Below we help clarify some of the unknowns.

UDI, UDI-DI and UDI-PI Primer

The UDI system (Unique Device Identification) is a regulatory framework for ensuring traceability and identification of medical devices. It includes multiple elements:

Each component plays a distinct role.

UDI-DI (Device Identifier)

The UDI-DI is a fixed, device-specific code assigned to one model or version of a product. It identifies attributes such as:

Each model or version must have its own unique UDI-DI.

UDI-PI (Production Identifier)

The UDI-PI provides production-level traceability. It is a variable code that includes data such as:

Unlike the fixed UDI-DI, the UDI-PI changes with each production batch or unit.

Under the EU MDR and IVDR, implementation of a full UDI system is mandatory. This was not required under the previous Directives (MDD, AIMDD, IVDD).

What is Basic UDI-DI?

The Basic UDI-DI is a “parent-level” identifier that groups together medical devices which share: the same intended purpose, risk class, and essential design and manufacturing characteristics.

It functions as a regulatory grouping tool, linking together all individual UDI-DIs within a device family. Among other things, this enables cohesive representation in EUDAMED and on the CE Certificate.

Think of the Basic UDI-DI as the umbrella code for a product line, with all related UDI-DIs feeding into it like branches under a tree.

Example: Devices Linked under a Basic UDI-DI

Let’s say you manufacture Foley catheters.

You offer a group of catheter models that all share the same intended purpose (urinary drainage), are classified under the same risk class (e.g., Class IIa), and have essentially the same design and manufacturing characteristics (e.g., 2-way, sterile, latex-free). These variations differ only in clinical size, for example: 8 Fr, 10 Fr, and 12 Fr.

Because these products are functionally and technically similar, you include them within the same Technical Documentation File (TDF) and issue a single Declaration of Conformity (DoC) covering all models. You title the file “Foley Catheters: 2-Way, Sterile.”

In this case, you would assign one Basic UDI-DI to represent the entire product group, i.e., the catheter family. Each size variation would still have its own UDI-DI (since size is a UDI-DI-defining attribute), but all of those UDI-DIs would be linked to the same Basic UDI-DI as their regulatory “parent.”

Is Basic UDI-DI needed if I only have a one device?

Yes. A Basic UDI-DI is still required even if you only have a single device or device model and no broader product “family.” In this case, you will assign one Basic UDI-DI and one UDI-DI to represent the product.

If you later introduce a new model, version, trade name, or vary a key attribute (e.g., a different clinical size or configuration), that new device will require its own UDI-DI. However, as long as the new version shares the same intended purpose, risk class, and essential design and manufacturing characteristics, it can still be linked to the same Basic UDI-DI. In this way, multiple UDI-DIs can be grouped under a single, consistent Basic UDI-DI.

Is Basic UDI-DI needed for Systems, Procedure Packs & Kits?

Yes. A Basic UDI-DI is required for Systems, Procedure Packs and Kits if they are marketed under the MDR/IVDR.

Each is defined as the following in the EU Commission’s EUDAMED Infographic Categorization of Devices:

‘System’ … means a combination of products, either packaged together or not, which are intended to be inter-connected or combined to achieve a specific medical purpose.

‘Procedure pack’ … means a combination of products packaged together and placed on the market with the purpose of being used for a specific medical purpose.

‘Kit’ … means a set of components that are packaged together and intended to be used to perform a specific in vitro diagnostic examination, or a part thereof.

If the System, Procedure Pack, IVD Kit is marketed under the old Directives, then a EUDAMED DI / EUDAMED ID may be required instead. Please see the below section on legacy devices for more information on this topic.

Is Basic UDI-DI needed for ‘legacy’ devices?

A Basic UDI-DI is not required for devices CE marked under the old Directives – it is only mandatory for MDR/IVDR CE marked devices.

However, that doesn’t mean that ‘legacy’ device manufacturers are completely exempt from this requirement. For the purposes of registering in EUDAMED, legacy devices will require a EUDAMED DI, which will perform a similar function as the Basic UDI-DI.

Where a legacy device manufacturer has a UDI system in place and UDI-DI applied for its devices, EUDAMED will auto-generate a EUDAMED DI when they register. Where a legacy device manufacturer does not yet have a UDI system in place, because UDI is not mandatory under the old Directives, then one will need to be created independent from a UDI-DI. This is called the EUDAMED ID.

The below is from the EU Commission’s User Guide:

EUDAMED DI: The EUDAMED DI corresponds to the Basic UDI-DI. It can either be entirely generated by EUDAMED if a UDI-DI has already been assigned to the legacy device, or the DI code can be partly assigned by the manufacturer (EUDAMED is the issuing entity for a EUDAMED DI)

EUDAMED ID: The EUDAMED ID corresponds to the UDI-DI. In case an UDI-DI has not already been assigned, the EUDAMED ID will always be automatically and fully generated by EUDAMED from the EUDAMED DI.

It can be somewhat of a confusing concept. But essentially, legacy devices will either have a EUDAMED DI or a EUDAMED ID, depending on if the manufacturer has a UDI system in place yet or not. Both the EUDAMED DI and EUDAMED ID are auto-created within the EUDAMED database.

This is different than the process for a Basic UDI-DI, where the manufacturer must procure the Basic UDI-DI outside of EUDAMED and then enter into EUDAMED.

Further, the EUDAMED DI / EUDAMED ID is not required to be listed in the device’s technical file, Declaration of Conformity, nor added to your MDD/AIMDD/IVDD CE Certificates. However, manufacturers may include the EUDAMED DI / EUDAMED ID to some technical documentation or procedures, as necessary for device traceability.

A final note on this topic is that EUDAMED is currently voluntary. Read more about registration requirements and timing on our EUDAMED Basics page.

Is Basic UDI-DI needed for custom-made devices?

No. Custom-made devices are exempt from Basic UDI-DI.

Custom-made devices (CMD) are not subject to UDI requirements as a whole, per MDR Article 27(1):

“The Unique Device Identification system (‘UDI system’) described in Part C of Annex VI shall allow the identification and facilitate the traceability of devices, other than custom-made and investigational devices, and shall consist of the following…”

Article 29(1) further states:

“Before placing a device, other than a custom-made device, on the market, the manufacturer shall, in accordance with the rules of the issuing entity referred to in Article 27(2), assign a Basic UDI-DI as defined in Part C of Annex VI to the device and shall provide it to the UDI database together with the other core data elements referred to in Part B of Annex VI related to that device.”

The MDCG guidance document 2021-3 also states:

“CMD manufacturers are exempt from device UDI registration, assignment and labelling requirements. As such, and although they must appoint a person responsible for regulatory compliance (PRRC) in accordance with Article 15 of the MDR, they are not required to register these persons in EUDAMED.”

Where will the Basic UDI-DI be listed?

The Basic UDI-DI must appear in the following:

*If you leverage your CE Certificate for an abridged review in a country like Australia or Singapore, those regulatory authorities will be able to identify all associated device models/versions since the Basic UDI-DI is listed on the certificate.

**Certificates of Free Sale are often used for registration in markets such as Saudi Arabia or the Philippines. 

Is Basic UDI-DI required on labeling?

No. The Basic UDI-DI is not required to appear on product labeling or packaging. It is a regulatory-level identifier used in documentation such as the Technical Documentation File, Declaration of Conformity, CE Certificate, Certificates of Free Sale, and EUDAMED registration.

Although it is part of the overall UDI system, the Basic UDI-DI is not encoded in the UDI carrier (e.g., barcode or RFID) found on the product label. Only the UDI-DI and UDI-PI are included in the carrier. However, in databases like EUDAMED, a UDI-DI can be linked back to its corresponding Basic UDI-DI for traceability purposes.

There is a transition period for the UDI carrier to be placed onto the device labeling:

MDR, Art. 123(f):

MDR, Art. 123(g):

…with regard to reusable devices that are required to bear the UDI carrier on the device itself, Article 27(4) shall apply to:

IVDR, Art. 113(e):

How do you obtain a Basic UDI-DI?

The Basic UDI-DI must be assigned by a recognized UDI issuing agency. As the manufacturer, you do not create this code yourself. When you enter a Basic UDI-DI into EUDAMED, the system will automatically verify that it was issued properly and is valid before allowing registration to proceed.

Let’s say your company already sells Foley catheters in the United States and has assigned UDI-DIs to your individual products in accordance with FDA requirements. In that case, you likely already have an account with a UDI issuing agency (e.g., GS1 or HIBCC). To comply with EU MDR, you’ll now need to generate one additional code: the Basic UDI-DI for your product family; in this case, your 2-way, sterile Foley catheters.

This Basic UDI-DI will group all related models (e.g., 8 Fr, 10 Fr, 12 Fr) under a single regulatory “umbrella.” Important: Only the following four issuing entities are recognized by the European Commission for Basic UDI-DI assignments

Several of these organizations offer online Basic UDI-DI generators for registered clients. For example:

Once generated, this Basic UDI-DI will be:

What does a Basic UDI-DI look like?

Per MDCG Guidance document 2019-1, at minimum, a Basic UDI-DI must have:

Because of this flexibility, the structure of the Basic UDI-DI will vary depending on the issuing agency you use. Below are example formats provided by the EU-recognized entities. The mandatory check character is shown in bold where applicable:

Basic UDI-DI Recap

Yes/No	Requirements
Yes	A Basic UDI-DI is required for devices CE marked under the EU MDR or IVDR
No	It is not required for devices CE marked under the MDD, AIMDD, or IVDD (i.e., legacy devices)
Yes	Functions as a top-level ‘parent’ identifier grouping a set of like devices
No	Is not required per individual device model within a grouped device family
No	Is not required for custom-made devices, which are exempt from UDI requirements
Yes	Must be issued by one of the four EU-recognized UDI issuing agencies (GS1, HIBCC, ICCBBA, IFA GmbH)
No	Is not required to appear on device labeling or promotional materials
Yes	ls required on the following:  – Technical Documentation File  – Declaration of Conformity  – CE Certificate  – Summary of Safety and Clinical Performance (SSCP) for Class III/implantables  – Certificates of Free Sale  – EUDAMED device registration