In the UDI vector (the GS1-128 or DataMatrix barcode on the label of the medical device), the expiry date must be encoded in the format YYMMDD (two-digit year, month, day). This requirement is imposed by the GS1 technical specification, the official UDI issuing body.

• Example: If the expiry date is September 30, 2023, the UDI vector (after the application identifier ’17’) will show ‘230930’.

It is essential to note that this specification only applies to the machine-readable part (UDI carrier). On the visible part of the label (HRI), e.g. next to the hourglass symbol, the date can be shown in the format DDD-MM or MM/DDD, under ISO 20417.

A UDI vector reporting the date in a format other than YYMMDD (e.g. DD/DD/MM) would constitute non-compliance with GS1 requirements, even if the meaning of the date were correct for human reading.