Unique Device Identification in the USA, FDA UDI Requirements Explained

Unique Device Identification, commonly referred to as UDI, is a foundational element of the FDA regulatory framework for medical devices in the United States. The system was established to improve traceability, strengthen post market surveillance, support recall efficiency and enhance patient safety. UDI also enables standardised identification of medical devices across electronic health records, clinical systems and supply chains. For manufacturers, UDI is not simply a labelling requirement. It is a lifecycle obligation that intersects with regulatory submissions, quality systems and field action management. Understanding how UDI operates in the US framework is essential for compliant market entry and ongoing regulatory maintenance.

Regulatory Framework for UDI in the United States

The UDI system is mandated under Section 519(f) of the Federal Food, Drug and Cosmetic Act and implemented through FDA regulations in 21 CFR Part 801 for labelling and 21 CFR Part 830 for UDI system specifications. These regulations define which devices are subject to UDI, how identifiers must be structured and where they must appear. The FDA maintains the Global Unique Device Identification Database, known as GUDID, which serves as the public repository for device identification data. GUDID is the US equivalent of EUDAMED and plays a central role in linking device identifiers to regulatory records, post market data and recall information.

Purpose and Value of the UDI System

The primary purpose of UDI is to create a consistent and unambiguous way to identify medical devices throughout their lifecycle. This improves traceability across manufacturing, distribution and clinical use. UDI strengthens post market surveillance by allowing adverse events and complaints to be linked to specific device versions and production lots. It supports faster and more targeted recalls by enabling manufacturers and regulators to identify affected units quickly. UDI also improves supply chain transparency and facilitates integration with hospital inventory systems and electronic health records. From a regulatory perspective, UDI provides the FDA with more reliable data to monitor device performance and safety trends over time.

Format and Structure of a UDI

A UDI must appear in both human readable interpretation and automatic identification and data capture formats for physical devices. The UDI is composed of two elements, the Device Identifier and the Production Identifier. The Device Identifier is mandatory for all devices subject to UDI, while the Production Identifier is included when the relevant production information appears on the label. For Class I devices, a Universal Product Code may be used as the UDI. Date formats on labels must follow the YYYY MM DD convention as specified in 21 CFR 801.18. The consistent application of format rules ensures that UDIs can be reliably scanned, interpreted and integrated across systems.

Device Identifier and When a New DI Is Required

The Device Identifier is the fixed portion of the UDI. It identifies the labeller and the specific device version or model and serves as the primary key within GUDID. A new Device Identifier is required when changes affect the intended use of the device, introduce major changes to safety or performance or trigger a new FDA submission such as a new 510(k) or De Novo. This requirement ensures that each materially distinct device version can be uniquely identified and traced. Manufacturers must therefore manage DI assignment carefully and align it with change control, regulatory submissions and version management processes.

Production Identifiers and Variable Information

The Production Identifier is the variable portion of the UDI and may include the lot number, batch number, serial number, expiration date or manufacturing date. Whether a PI is required and which elements must be included depends on device type, manufacturing controls and labelling practices. Production Identifiers enable unit level or lot level traceability, which is critical for complaint investigation, adverse event reporting and recalls. Manufacturers must ensure that PI logic is consistent across labelling, internal records and quality system processes.

FDA Accredited Issuing Agencies

UDI codes must be obtained from an FDA accredited issuing agency. The main agencies are GS1, HIBCC and ICCBBA. Each agency offers different coding structures and services, and manufacturers must select an agency based on global coding needs, supply chain compatibility, customer requirements and cost. The choice of issuing agency has long term implications, particularly for companies operating across multiple jurisdictions or selling through complex distribution networks. Once selected, the issuing agency relationship becomes part of the manufacturer’s regulatory infrastructure.

UDI Requirements for Physical and Hardware Devices

For physical devices, UDI must appear on the device label and on all packaging levels intended for commercial distribution, except shipping containers used solely for logistics. Both human readable and AIDC formats are required. Reusable devices that undergo reprocessing must be directly marked with the UDI unless an exception applies. Direct marking ensures that the device remains identifiable even when packaging is removed. GUDID submissions for hardware devices must include detailed information such as packaging hierarchy, sterilisation status, MRI safety information and device identifiers. These data elements must be kept current throughout the device lifecycle.

UDI Requirements for Software and SaMD

Software medical devices, including stand alone software, are subject to specific UDI requirements. The UDI must be displayed on the splash screen or startup sequence and be accessible through an About, Info or Help menu. It must also appear in electronic labelling. If the software is distributed on physical media, the UDI must also appear on the packaging. Versioning is central to software UDI management. Major software updates that affect safety, performance or intended use require a new Device Identifier. Minor updates such as bug fixes, cosmetic interface changes or cybersecurity patches typically require only a Production Identifier update. Manufacturers must maintain clear criteria to distinguish between DI triggering changes and PI only updates.

AI and Machine Learning Enabled Devices

AI and machine learning enabled devices follow the same UDI principles as other software devices, with additional considerations due to adaptive algorithms. Where an AI device is approved under a Predetermined Change Control Plan, algorithm updates within the approved boundaries may only require Production Identifier updates. Significant model changes outside the approved plan require a new Device Identifier. Cloud based AI devices must still display the UDI in the user interface and maintain traceable version histories. Robust version control and documentation are essential to demonstrate compliance.

GUDID Submission Responsibilities

The labeller is responsible for the accuracy and maintenance of GUDID records. For software devices, GUDID includes fields such as delivery mechanism, supported operating systems and software version. For hardware devices, packaging details and physical attributes must be provided. Manufacturers must establish GUDID accounts, define user roles, select submission methods and ensure timely updates when changes occur. Failure to maintain accurate GUDID data can lead to regulatory findings and disrupt market access.

UDI Exemptions and Exclusions

Not all devices are subject to UDI.

Devices which are exempt include:

• Custom-made devices (which meet section 520(b) criteria
• Investigational devices labelled for investigational use under 21 CFR 812
• Class I devices which are exempt from GMP requirements under 21 CFR Parts 862 to 892
• Veterinary use devices not intended for human use
• Components (e.g. sub-assemblies or boards) are exempt
  • Note that this does not include accessories, which do require UDI

Additionally, outer shipping containers used only for transport are exempt. Legacy enforcement delays largely expired by December 2022, so most devices entering the US market should assume full compliance unless a formal exemption applies.

Implementation by Device Class and Type

UDI implementation timelines vary by device class. Class III and life supporting or life sustaining devices have been fully in scope since 2014 to 2016. Class II devices have required labelling and GUDID submission since 2016, with direct marking requirements for reusable devices applying from 2018. Class I and unclassified devices have required labelling and GUDID submission since 2018, with final enforcement from December 2022. Stand alone software across all classes must display the UDI within the interface and include version information. Convenience kits require a UDI on the kit label, while components within the immediate container are excepted if the kit meets FDA definitions.

Practical Checklist for Manufacturers

Manufacturers should begin by confirming device classification and labeller status and selecting an FDA accredited issuing agency. Device versions and packaging levels must be mapped to Device Identifiers and Production Identifiers, and Class I UPC eligibility assessed. Labels must be designed to include UDI in human readable and AIDC formats with compliant date presentation. Decisions on direct marking should be documented, including any exceptions. Software interfaces must display the UDI and version appropriately. GUDID accounts should be prepared early, and submission timelines planned. Finally, UDI should be integrated into complaint handling, MDR reporting and field action processes to enable rapid identification of affected devices.LFH supports medical device manufacturers in implementing compliant UDI strategies across hardware, software and AI enabled products. Our team provides end to end support from issuing agency selection and GUDID submission to change control alignment and post market integration, helping organisations meet FDA expectations with confidence.

FAQ – FDA UDI Requirements Explained