A vehicle registration plate is a metal or plastic plate attached to a motor vehicle or trailer for official identification purposes.
| Code | County and/or City | Irish |
|---|---|---|
| C | County Cork and Cork City | Corcaigh |
| CE | Clare | An Clár |
| CN | Cavan | An Cabhán |
| CW | Carlow | Ceatharlach |
| D | County Dublin and Dublin City | Baile Átha Cliath |
| DL | Donegal | Dún na nGall |
| G | County Galway and Galway City | Gaillimh |
| KE | Kildare | Cill Dara |
| KK | Kilkenny | Cill Chainnigh |
| KY | Kerry | Ciarraí |
| LD | Longford | An Longfort |
| LH | Louth | Lú |
| L | County Limerick and Limerick City (City only Before 2014) | Luimneach |
| LK | County Limerick (Before 2014) | Luimneach |
| LM | Leitrim | Liatroim |
| LS | Laois | Laois |
| MH | Meath | An Mhí |
| MN | Monaghan | Muineachán |
| MO | Mayo | Maigh Eo |
| OY | Offaly | Uíbh Fhailí |
| RN | Roscommon | Ros Comáin |
| SO | Sligo | Sligeach |
| T | North and South Tipperary | Tiobraid Árann |
| TN | North Tipperary (Before 2014) | Tiobraid Árann |
| TS | South Tipperary (Before 2014) | Tiobraid Árann |
| W | Waterford City and County Waterford (City only before 2014) | Port Láirge |
| WD | County Waterford (Before 2014) | Port Láirge |
| WH | Westmeath | An Iarmhí |
| WX | Wexford | Loch Garman |
| WW | Wicklow | Cill Mhantáin |
Former index mark codes[]
Codes no longer used from 2014:
| Code | County and/or City |
|---|---|
| LK | County Limerick |
| TN | North Tipperary |
| TS | South Tipperary |
| WD | County Waterford |