| ISL | 0 | United Kingdom | GB-ISL |
| Istria County | 0 | Croatia | HR-18 |
| IVA | 0 | Russia | RU-IVA |
| Ivančna Gorica Municipality | 0 | Slovenia | SI-039 |
| Ivano-Frankivsk Oblast | 0 | Ukraine | UA-26 |
| IVC | 0 | United Kingdom | GB-IVC |
| Izola Municipality | 0 | Slovenia | SI-040 |
| Jablanica District | 0 | Serbia | RS-23 |
| Jablonec nad Nisou | 0 | Czech Republic | CZ-512 |
| Jan Mayen | 0 | Norway | NO-22 |
| Järva County | 0 | Estonia | EE-51 |
| Jaunjelgava Municipality | 0 | Latvia | LV-038 |
| Jaunpiebalga Municipality | 0 | Latvia | LV-039 |
| Jaunpils Municipality | 0 | Latvia | LV-040 |
| Jegunovce Municipality | 0 | Republic of North Macedonia | MK-35 |
| Jēkabpils | 0 | Latvia | LV-JKB |
| Jēkabpils Municipality | 0 | Latvia | LV-042 |
| Jelgava | 0 | Latvia | LV-JEL |
| Jelgava Municipality | 0 | Latvia | LV-041 |
| Jesenice Municipality | 0 | Slovenia | SI-041 |
| Jeseník | 0 | Czech Republic | CZ-711 |
| Jezersko Municipality | 0 | Slovenia | SI-163 |
| Jičín | 0 | Czech Republic | CZ-522 |
| Jihlava | 0 | Czech Republic | CZ-632 |
| Jihočeský kraj | 0 | Czech Republic | CZ-31 |
| Jihomoravský kraj | 0 | Czech Republic | CZ-64 |
| Jindřichův Hradec | 0 | Czech Republic | CZ-313 |
| JN | 0 | Hungary | HU-JN |
| Jõgeva County | 0 | Estonia | EE-49 |
| Jonava District Municipality | 0 | Lithuania | LT-10 |
| Joniškis District Municipality | 0 | Lithuania | LT-11 |
| Jönköping County | 0 | Sweden | SE-F |
| JU | 0 | Switzerland | CH-JU |
| Jurbarkas District Municipality | 0 | Lithuania | LT-12 |
| Jūrmala | 0 | Latvia | LV-JUR |
| Juršinci Municipality | 0 | Slovenia | SI-042 |
| Kainuu | 0 | Finland | FI-05 |
| Kaišiadorys District Municipality | 0 | Lithuania | LT-13 |
| Kalkara | 0 | Malta | MT-21 |
| Kalmar County | 0 | Sweden | SE-H |
| Kalvarija municipality | 0 | Lithuania | LT-14 |
| KAM | 0 | Russia | RU-KAM |
| Kamnik Municipality | 0 | Slovenia | SI-043 |
| Kanal ob Soči Municipality | 0 | Slovenia | SI-044 |
| Kandava Municipality | 0 | Latvia | LV-043 |
| Karbinci | 0 | Republic of North Macedonia | MK-37 |
| Karditsa Regional Unit | 0 | Greece | GR-41 |
| Kardzhali Province | 0 | Bulgaria | BG-09 |
| Karlovarský kraj | 0 | Czech Republic | CZ-41 |
| Karlovy Vary | 0 | Czech Republic | CZ-412 |
| Karpoš Municipality | 0 | Republic of North Macedonia | MK-38 |
| Kārsava Municipality | 0 | Latvia | LV-044 |
| Karviná | 0 | Czech Republic | CZ-803 |
| Kastoria Regional Unit | 0 | Greece | GR-56 |
| Kaunas City Municipality | 0 | Lithuania | LT-15 |
| Kaunas County | 0 | Lithuania | LT-KU |
| Kaunas District Municipality | 0 | Lithuania | LT-16 |
| Kavadarci Municipality | 0 | Republic of North Macedonia | MK-36 |
| Kavajë District | 0 | Albania | AL-KA |
| Kazlų Rūda municipality | 0 | Lithuania | LT-17 |
| KB | 0 | Russia | RU-KB |
| KC | 0 | Russia | RU-KC |
| KDA | 0 | Russia | RU-KDA |
| KE | 0 | Ireland | IE-KE |
| KEC | 0 | United Kingdom | GB-KEC |
| Kėdainiai District Municipality | 0 | Lithuania | LT-18 |
| Kefalonia Prefecture | 0 | Greece | GR-23 |
| Ķegums Municipality | 0 | Latvia | LV-051 |
| Ķekava Municipality | 0 | Latvia | LV-052 |
| Kelmė District Municipality | 0 | Lithuania | LT-19 |
| KEM | 0 | Russia | RU-KEM |
| KEN | 0 | United Kingdom | GB-KEN |
| Kerċem | 0 | Malta | MT-22 |
| KGD | 0 | Russia | RU-KGD |
| KGN | 0 | Russia | RU-KGN |
| KHA | 0 | Russia | RU-KHA |
| Kharkiv Oblast | 0 | Ukraine | UA-63 |
| Kherson Oblast | 0 | Ukraine | UA-65 |
| KHL | 0 | United Kingdom | GB-KHL |
| KHM | 0 | Russia | RU-KHM |
| Khmelnytsky Oblast | 0 | Ukraine | UA-68 |
| KI | 0 | Slovakia | SK-KI |
| Kičevo Municipality | 0 | Republic of North Macedonia | MK-40 |
| Kidričevo Municipality | 0 | Slovenia | SI-045 |
| Kiev | 0 | Ukraine | UA-30 |
| Kilkis Regional Unit | 0 | Greece | GR-57 |
| KIR | 0 | United Kingdom | GB-KIR |
| KIR | 0 | Russia | RU-KIR |
| Kirkop | 0 | Malta | MT-23 |
| Kirovohrad Oblast | 0 | Ukraine | UA-35 |
| Kisela Voda Municipality | 0 | Republic of North Macedonia | MK-39 |
| KK | 0 | Russia | RU-KK |
| KK | 0 | Ireland | IE-KK |
| KL | 0 | Russia | RU-KL |
| Kladno | 0 | Czech Republic | CZ-203 |
| Klaipeda City Municipality | 0 | Lithuania | LT-20 |
| Klaipėda County | 0 | Lithuania | LT-KL |
| Klaipėda District Municipality | 0 | Lithuania | LT-21 |
| Klatovy | 0 | Czech Republic | CZ-322 |
| KLU | 0 | Russia | RU-KLU |
