The first registrations numbers were allocated in 1903,  the “I” standing for Ireland prefixed each letter of the alphabet as designated initially to each county/city in alphabetical order. It then switched to take up the remaining designated letters.  G, S and V were reserved until the 1980s. Q was never used. In later years as required, the two letters were prefixed with a third letter – in alphabetical order by county eg ABI, BBI etc, and later still,  the letters reverted from prefix to follow the numbers. Eg  BI 9999 and 6540BI. The current system of registrations began in 1987.

Code County
BI Monaghan

Monaghan – history:   BI

BI 1 to BI 9999 (Dec 1903 – Mar 1961).

ABI 1 to ZBI 999 (Mar 1961 – Oct 1981).

1 BI to 6540 BI (Oct 1981 – Dec 1986).

All Old Irish County Reg abbreviations

letter code (Ix) County or city code(xI) County or city code (Zx) County or city
A IA Antrim AI Meath ZA Dublin City
B IB Armagh BI Monaghan ZB Cork County
C IC Carlow CI Laois (formerly Queen’s County) ZC Dublin City
D ID Cavan DI Roscommon ZD Dublin City
E IE Clare EI Sligo ZE Dublin County
F IF Cork County FI Tipperary North Riding ZF Cork City
H IH Donegal HI Tipperary South Riding ZH Dublin City
J IJ Down JI Tyrone ZJ Dublin City
K IK Dublin County KI Waterford County ZK Cork County
L IL Fermanagh LI Westmeath ZL Dublin City
M IM Galway MI Wexford ZM Galway County
N IN Kerry NI Wicklow ZN Meath
O IO Kildare OI Belfast ZO Dublin City and County
P IP Kilkenny PI Cork City ZP Donegal
R IR Offaly (formerly King’s County) RI Dublin City ZR Wexford
T IT Leitrim TI Limerick City ZT Cork County
U IU Limerick County UI Derry ZU Dublin City and County
W IW County Londonderry WI Waterford City ZW Kildare
X IX Longford XI Belfast City ZX Kerry
Y IY Louth YI Dublin City ZY Louth
Z IZ Mayo ZI Dublin City ZZ Temporary registrations
Z Dublin County
G IG Fermanagh (from 2004) GI Tipperary South Riding (from 1985) ZG Dublin City and County (from 1983)
S IS Mayo (from 1983) SI Dublin City and County (from 1982) ZS Dublin City and County (from 1984)
V IV Limerick (from 1982) VI ZV Dublin City and County (from 1985) / vehicles >30 years old

Series history per county 1903–1986

Carlow CC: IC

IC 1 to IC 99991 (Dec 1903 – Apr 1964).

AIC 1 to YIC 994 (Apr 1964 – Dec 1986).

1 A duplicate series of IC for cars and motorcycles existed prior to 1921.

Cavan CC: ID

ID 1 to ID 9999 (Jan 1904 – Jul 1958).

AID 1 to ZID 999 (Jul 1958 – Dec 1976).

1 ID to 9999 ID (Dec 1976 – Feb 1981).

1 AID to 906 IID (Feb 1981 – Dec 1986).

Clare CC: IE

IE 1 to IE 99992 (Jan 1904 – Mar 1959).

AIE 1 to ZIE 999 (Mar 1959 – Nov 1974).

1 IE to 9999 IE (Nov 1974 – Sep 1978).

1 AIE to 107 XIE (Sep 1978 – Dec 1986).

2 A duplicate series of IE for cars and motorcycles existed prior to 1921.

Cork CC: (in original issuing sequence) IF ZB ZK ZT

IF 1 to IF 9999 (Dec 1903 – Apr 1935);

ZB 1 to ZB 9999 (Apr 1935 – Apr 1949);

ZK 1 to ZK 9999 (Apr 1949 – May 1953);

ZT 1 to ZT 9999 (May 1953 – Dec 1955).

AIF 1 to ZIF 999 (Dec 1955 – Apr 1962);

AZB 1 to YZB 999 (Apr 1962 – Aug 1966);

AZK 1 to YZK 999 (Aug 1966 – Aug 1970);

AZT 1 to YZT 999 (Aug 1970 – Nov 1973).

1 IF to 9999 IF (Nov 1973 – May 1975);

1 ZB to 9999 ZB (May 1975 – Jul 1976);

1 ZK to 9999 ZK (Jul 1976 – Aug 1977);

1 ZT to 9999 ZT (Aug 1977 – Jun 1978).

1 AIF to 999 ZIF (Jun 1978 – Sep 1980);

1 AZB to 999 YZB (Sep 1980 – Jun 1983);

1 AZK to 999 PZK (Jun 1983 – Aug 1985);

1 RZK to 999 YZK (Aug 1985 – May 1986).

In June 1974 Cork County Council and Cork County Borough Council set up a joint motor taxation authority, administered by the County Council. However, separate registers continued in use for the County and the County Borough until the expiry of reverse ZPI in August 1985. See below for the sequences issued covering both areas. Marks in italics are after the merger.

Cork City: (in original issuing sequence) PI ZF

PI 1 to PI 9999 (Dec 1903 – Aug 1946);

ZF 1 to ZF 9999 (Aug 1946 – Dec 1958).

API 1 to ZPI 999 (Dec 1958 – Feb 1970);

AZF 1 to YZF 999 (Feb 1970 – Mar 1976).

1 PI to 9999 PI (Mar 1976 – Jun 1978);

1 ZF to 9999 ZF (Jun 1978 – Feb 1980).

1 API to 999 ZPI (Feb 1980 – Aug 1985).

In June 1974 Cork County Council and Cork County Borough Council set up a joint motor taxation authority, administered by the County Council. However, separate registers continued in use for the County and the County Borough until the expiry of reverse ZPI in August 1985. See below for the sequences issued covering both areas.

Cork County and County Borough Joint Office: (in issuing sequence) reverse RZK-YZK, reverse AZF-FZF

1 RZK to 999 YZK (Aug 1985 – May 1986);

1 AZF to 542 FZF (May 1986 – Dec 1986).

Donegal CC: (in original issuing sequence) IH ZP

IH 1 to IH 99993 (Dec 1903 – Jan 1952);

ZP 1 to ZP 9999 (Jan 1952 – Nov 1961).

AIH 1 to ZIH 999 (Nov 1961 – Apr 1976);

AZP 1 to ZZP 4074 (Apr 1976 – Feb 1982).

408 IH to 9999 IH (Feb 1982 – Apr 1985);

1 ZP to 4853 ZP (Apr 1985 – Dec 1986).

3 A duplicate series of IH for cars and motorcycles existed prior to 1921.

4 ZZP was not authorised by SR&O (Statutory Rules & Orders) and was issued in error – no retrospective SR&O was issued to legitimise its issue. When the error was discovered ZZP was terminated at 407; in consequence the next series (reverse IH) commenced at 408.

Dublin CC (until 1952): (in original issuing sequence) IK Z ZE

IK 1 to IK 99995 (Dec 1903 – Mar 1927);

Z 1 to Z 9999 (Mar 1927 – Sep 1938);

ZE 1 to ZE 9999 (Sep 1938 – Feb 1952).

5 A duplicate series of IK for cars and motorcycles existed prior to 1921.

In February 1952 Dublin County Council and Dublin County Borough Council set up a joint motor taxation authority. The joint office was administered by Dublin County Borough Council. See below for subsequent issues.

Dublin City (until 1952): (in original issuing sequence) RI YI ZI ZA ZC ZD ZH ZJ ZL

RI 1 to RI 99996 (Dec 1903 – Apr 1921);

YI 1 to YI 9999 (Apr 1921 – Mar 1927);

ZI 1 to ZI 9999 (Mar 1927 – May 1933);

ZA 1 to ZA 9999 (May 1933 – Mar 1937);

ZC 1 to ZC 9999 (Mar 1937 – Jan 1940);

ZD 1 to ZD 9999 (Jan 1940 – Jan 1947);

ZH 1 to ZH 9999 (Jan 1947 – Jan 1949);

ZJ 1 to ZJ 9999 (Jan 1949 – Jul 1950);

ZL 1 to ZL 9999 (Jul 1950 – Feb 1952).

6 A duplicate series up to RI 3000 for cars and motorcycles existed prior to 1921.

In February 1952 Dublin County Council and Dublin County Borough Council set up a joint motor taxation authority. The joint office was administered by Dublin County Borough Council. See below for subsequent issues.

Dublin County and County Borough Joint Office (from February 1952): (in original issuing sequence) forward 2-letter sequences of ZO ZU; then forward 3-letter combinations of RI IK YI ZA ZC ZD ZE ZH ZI ZJ ZL ZO ZU; then reverse 2-letter sequences of RI IK YI Z ZA ZC ZD ZE ZH ZI ZJ ZL ZO ZU; then reverse 3-letter combinations of RI IK YI ZA ZC ZD ZE ZH ZI ZJ ZL ZO ZU; then forward 3-letter combinations of SI ZG ZS ZV; then reverse 2-letter sequences of SI ZG ZS.

ZO 1 to ZO 9999 (Feb 1952 – May 1953);

ZU 1 to ZU 9999 (May 1953 – May 1954).

ARI 1 to YRI 9997 (May 1954 – Sep 1955);

AIK 1 to ZIK 9998 (Sep 1955 – Nov 1957);

AYI 1 to YYI 9999 (Nov 1957 – Oct 1959);

AZA 1 to YZA 999 (Oct 1959 – Jan 1961);

AZC 1 to YZC 999 (Jan 1961 – Apr 1962);

AZD 1 to YZD 999 (Apr 1962 – May 1963);

AZE 1 to YZE 999 (May 1963 – Jun 1964);

AZH 1 to YZH 999 (Jun 1964 – May 1965);

AZI 1 to YZI 999 (May 1965 – Jun 1966);

AZJ 1 to YZJ 999 (Jun 1966 – Jun 1967);

AZL 1 to YZL 999 (Jun 1967 – May 1968);

AZO 1 to YZO 999 (May 1968 – Mar 1969);

AZU 1 to YZU 999 (Mar 1969 – Feb 1970).

1 RI to 9999 RI (Feb – May 1970);

1 IK to 9999 IK (May – Sep 1970);

1 YI to 9999 YI (Sep 1970 – Feb 1971);

1 Z to 9999 Z (Feb – Jun 1971);

1 ZA to 9999 ZA (Jun – Oct 1971);