If you’ve ever spotted an Irish number plate with a puzzling two-letter code like “WW” or “OY,” you’re not alone. Those letters actually tell you exactly which county the car was first registered in — and the system has been in place, with a few changes, since 1903.

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County codes: 26 (plus city codes) ·
Current format introduced: 1987 ·
Old system started: 1903 ·
Year suffix letters used: 1945–1986 ·
Estimated registered vehicles: 2.7 million+ (2023)

Quick snapshot

1Confirmed facts
2What’s unclear
  • Complete database of pre-1903 registrations may be incomplete
  • Some old county prefixes may have multiple variations
3Timeline signal
4What’s next
  • EU-wide digitisation may connect plate databases
  • Possible shift to all-digital registration certificates
Attribute Value
Current registration format YYYY–CC–###### (e.g., 2024–D–123456)
First vehicle registration year 1903
Year suffix letter introduced 1945
Current system start date 1 January 1987
Number of county codes 26 (plus separate city codes)
Authority responsible Revenue Commissioners / Road Safety Authority

How to Check Irish Number Plates?

Can I look up a car by its Irish plate?

  • Irish number plates do not publicly reveal owner information. The official register is managed by the Department of Transport and the Road Safety Authority (Radiator Service (specialist parts supplier)).
  • You can check basic vehicle details (make, model, year, engine size) via the National Vehicle and Driver File (NVDF) or through commercial services like Motorcheck.ie and Cartell.ie.

How to check who owns a car in Ireland?

  • Full owner information is restricted to Gardaí and authorised parties. Third-party services charge a fee for detailed history reports but cannot reveal the owner’s name (Revenue (official tax authority) guidance).
Bottom line: You can look up a car’s technical specs from its plate, but not the owner’s name. For used-car buyers, a commercial history check is the best option — just don’t expect names.

What Do the Letters on Irish Number Plates Mean?

What are the county codes for Irish plates?

A complete list of current county codes is published by Revenue (Revenue (official tax authority) guidance). The table below shows all 26 county codes plus city codes.

What does WW stand for?

What does MH stand for?

  • MH is County Meath (Wikipedia (encyclopedic reference)).

What does W mean on Irish plates?

  • W is the current code for County Waterford. Before 2014, Waterford used WD (Wikipedia (encyclopedic reference)).

What does OY mean on Irish plates?

  • OY is County Offaly (Wikipedia (encyclopedic reference)).

Six rows of county codes follow one pattern: single-letter codes for the largest cities, two-letter codes for counties to avoid clashes.

Code County / City Irish Name Notes
C Cork Corcaigh Single-letter code
CE Clare An Clár
CN Cavan An Cabhán
CW Carlow Ceatharlach
D Dublin Baile Átha Cliath Single-letter code
DL Donegal Dún na nGall
G Galway Gaillimh Single-letter code
KE Kildare Cill Dara
KK Kilkenny Cill Chainnigh
KY Kerry Ciarraí
L Limerick Luimneach Single-letter code
LD Longford An Longfort
LH Louth Lú
LM Leitrim Liatroim
LS Laois Laois Previously LS
MH Meath An Mhí
MN Monaghan Muineachán
MO Mayo Maigh Eo
OY Offaly Uíbh Fhailí
RN Roscommon Ros Comáin
SO Sligo Sligeach
T Tipperary Tiobraid Árann Single-letter code; formerly TN (North) and TS (South)
W Waterford Port Láirge Single-letter code; formerly WD
WH Westmeath An Iarmhí
WW Wicklow Cill Mhantáin
WX Wexford Loch Garman

The pattern: single letters for major cities, double letters for counties, with deliberate gaps to avoid duplication.

Why it matters

The code clash between Kilkenny and Kerry is the reason Kerry uses KY and Kilkenny uses KK — a small historical compromise that still confuses drivers today.

Bottom line: The two-letter codes are systematic: single letters for major cities, double letters for counties, with deliberate gaps to avoid duplication. For buyers, the county code is a quick way to guess the car’s origin.

Irish Car Registration Numbers Pre 1987: Understanding the Old System

What was the format before 1987?

  • Before 1987, plates used a county code prefix (one or two letters) followed by a serial number. From 1945 to 1986, a year suffix letter was added (Wikipedia (encyclopedic reference)).
  • Single-letter county codes were used for Dublin (D), Cork (C), and others.

How to read old Irish plates?

  • Example: “D 12345” means Dublin, serial 12345 (no year letter). “D 12345 Z” would be a 1970 registration (Z = 1970).
  • The year letters started with A in 1945, B in 1946, and so on, skipping some letters to avoid confusion (Radiator Service (specialist parts supplier)).
Bottom line: If you see a five-digit serial with a single letter at the end, you’re looking at a classic Irish plate. The year letter makes it possible to date the car within a four-decade window.

How to Trace Old Irish Car Registration Numbers?

What is the process for tracing old registration numbers?

  1. Step 1: Note the county code and year letter (if any).
  2. Step 2: Contact the local motor tax office for that county — they may have paper records for very old registrations.
  3. Step 3: Use the NVDF online service (basic details only).
  4. Step 4: For a detailed history, use a commercial service like Motorcheck.ie or Cartell.ie (Revenue (official tax authority) guidance).

Are there online databases for old Irish plates?

  • Some third-party websites maintain historical databases. However, the most complete official source is the Revenue PDF listing all registration districts (Revenue (official tax authority)).
Bottom line: Tracing an old plate is possible but requires patience. For a car enthusiast, the county code and year letter are often enough to tell a story.

Is There an Irish Car Registration Database?

How to access the official database?

  • The official database is maintained by the Department of Transport and the Road Safety Authority (RSA). Public access is limited to basic details via the NVDF (Radiator Service (specialist parts supplier)).

What information is available publicly?

  • Make, model, year of registration, engine size, and current colour. Owner name and address are not public (Revenue (official tax authority) guidance).
Bottom line: The official database is a black box for ownership. For buyers, a commercial history report is the only way to get meaningful data.

Timeline of Irish Registration Plates

  • 1903: First vehicle registration plates introduced by local authorities.
  • 1945: Year suffix letter added to registration numbers (Wikipedia (encyclopedic reference)).
  • 1987: Current YYYY-CC-###### format launched (Revenue (official tax authority)).
  • 1990: Introduction of European blue band on left side (Radiator Service (specialist parts supplier)).
  • 2014: Tipperary split into North (TN) and South (TS) codes (Wikipedia (encyclopedic reference)).

Confirmed facts

  • County codes list is published by Revenue (Revenue (official tax authority))
  • Year letters used 1945–1986 are documented (Wikipedia (encyclopedic reference))
  • Ownership is not public information (Radiator Service (specialist parts supplier))

What’s unclear

  • Exact complete database of pre-1903 registrations may be incomplete
  • Some old county prefixes may have multiple variations

The current year-county-serial format was introduced in 1987 to standardise registration across all counties.

Revenue Commissioners (official tax authority) guidance

Prior to 1987, registration numbers followed a county prefix and serial number system with optional year letter.

Wikipedia – Vehicle registration plates of the Republic of Ireland

For the driver in the market for a used car from Ireland, the plate tells you where the car started its life, but not its full history. That requires a paid check.

Additional sources

dashdynamics.co.uk, eire.fandom.com, licenseplatemania.com

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Frequently Asked Questions

What does the ‘D’ on an Irish number plate mean?

D stands for Dublin. It’s one of the few single-letter county codes used on the current format.

Can I get a personalised Irish number plate?

Yes, you can apply for a personalised plate through the Department of Transport, but it must follow the standard format and include the county code.

What is the cost of a new Irish registration plate?

Costs vary by supplier, typically €20–€50. The main expense is the VRT (Vehicle Registration Tax) when importing a car.

How do I transfer a registration plate to another vehicle in Ireland?

Plate transfers are not allowed under current Irish law — the plate stays with the vehicle for its lifetime.

What is the penalty for having a non-standard plate in Ireland?

Non-compliant plates can result in a fine and may cause the vehicle to fail its NCT (National Car Test).

Are Irish number plates legal in the UK?

Yes, Irish plates are recognised in the UK. However, if you move to the UK permanently, you may need to re-register the vehicle.

For anyone buying a used car in Ireland, the choice is straightforward: use a commercial history check to uncover hidden problems, or risk inheriting a vehicle with a past you can’t see. The plate is just the start.