Vehicle registration plates of the Republic of Ireland Vehicle registration plates of the Republic of Ireland In the Republic of Ireland, vehicle registration plates (commonly known as "number plates") are the visual indications of motor vehicle registration – officially termed "index marks" – which it has been mandatory since 1903 to display on most motor vehicles used on public roads in Ireland. The alphanumeric marks (or "registration numbers") themselves were issued by the local authority in which a vehicle is first registered. The current specification for number plates is the format YYY–CC–SSSSSS. Those issued from 1987 to 2012 had the format YY–CC–SSSSSS. The components are: Since 1991, the
International vehicle registration code International vehicle registration code The country in which a motor vehicle's vehicle registration plate was issued may be indicated by an international licence plate country code, formerly known as an International Registration Letter or International Circulation Mark. The sign must be displayed on the rear of the vehicle. The sign may either be placed separately from the registration plate, or be incorporated into the vehicle registration plate. The allocation of codes is maintained by the United Nations Economic Commission for Europe as the "Distinguishing Signs Used on Vehicles in International Traffic" (sometimes abbreviated to DSIT), authorised by the UN's Geneva