| SWD | 0 | United Kingdom | GB-SWD |
| Swieqi | 0 | Malta | MT-57 |
| SWK | 0 | United Kingdom | GB-SWK |
| SZ | 0 | Hungary | HU-SZ |
| SZ | 0 | Switzerland | CH-SZ |
| TA | 0 | Moldova | MD-TA |
| TA | 0 | Russia | RU-TA |
| TA | 0 | Slovakia | SK-TA |
| TA | 0 | Ireland | IE-TA |
| Ta' Xbiex | 0 | Malta | MT-58 |
| Tábor | 0 | Czech Republic | CZ-317 |
| Tabor Municipality | 0 | Slovenia | SI-184 |
| Tachov | 0 | Czech Republic | CZ-327 |
| Talsi Municipality | 0 | Latvia | LV-097 |
| TAM | 0 | United Kingdom | GB-TAM |
| TAM | 0 | Russia | RU-TAM |
| Targovishte Province | 0 | Bulgaria | BG-25 |
| Tartu County | 0 | Estonia | EE-78 |
| Tarxien | 0 | Malta | MT-59 |
| TAS | 0 | Australia | AU-TAS |
| Tauragė County | 0 | Lithuania | LT-TA |
| Tauragė District Municipality | 0 | Lithuania | LT-50 |
| Tavastia Proper | 0 | Finland | FI-06 |
| TB | 0 | Hungary | HU-TB |
| TC | 0 | Slovakia | SK-TC |
| TE | 0 | Moldova | MD-TE |
| Tearce Municipality | 0 | Republic of North Macedonia | MK-75 |
| Telemark | 0 | Norway | NO-08 |
| Telšiai County | 0 | Lithuania | LT-TE |
| Telšiai District Municipality | 0 | Lithuania | LT-51 |
| Tepelenë District | 0 | Albania | AL-TE |
| Teplice | 0 | Czech Republic | CZ-426 |
| Ternopil Oblast | 0 | Ukraine | UA-61 |
| Tērvete Municipality | 0 | Latvia | LV-098 |
| Tetovo Municipality | 0 | Republic of North Macedonia | MK-76 |
| TFW | 0 | United Kingdom | GB-TFW |
| TG | 0 | Switzerland | CH-TG |
| TH | 0 | Germany | DE-TH |
| Thessaloniki Regional Unit | 0 | Greece | GR-54 |
| THR | 0 | United Kingdom | GB-THR |
| TI | 0 | Switzerland | CH-TI |
| Tirana County | 0 | Albania | AL-11 |
| Tirana District | 0 | Albania | AL-TR |
| Tišina Municipality | 0 | Slovenia | SI-010 |
| Tivat Municipality | 0 | Montenegro | ME-19 |
| TL | 0 | Romania | RO-TL |
| TM | 0 | Romania | RO-TM |
| TN | 7 | United States | US-TN |
| TO | 0 | Hungary | HU-TO |
| TOB | 0 | United Kingdom | GB-TOB |
| TOF | 0 | United Kingdom | GB-TOF |
| Tolmin Municipality | 0 | Slovenia | SI-128 |
| TOM | 0 | Russia | RU-TOM |
| Toplica District | 0 | Serbia | RS-21 |
| TR | 0 | Romania | RO-TR |
| Trakai District Municipality | 0 | Lithuania | LT-52 |
| Trbovlje Municipality | 0 | Slovenia | SI-129 |
| Třebíč | 0 | Czech Republic | CZ-634 |
| Trebnje Municipality | 0 | Slovenia | SI-130 |
| Trentino | 0 | Italy | IT-TN |
| Trentino-South Tyrol | 0 | Italy | IT-32 |
| TRF | 0 | United Kingdom | GB-TRF |
| Triesen | 0 | Liechtenstein | LI-09 |
| Triesenberg | 0 | Liechtenstein | LI-10 |
| Trnovska Vas Municipality | 0 | Slovenia | SI-185 |
| Troms | 0 | Norway | NO-19 |
| Trøndelag | 0 | Norway | NO-50 |
| Tropojë District | 0 | Albania | AL-TP |
| Trutnov | 0 | Czech Republic | CZ-525 |
| Tržič Municipality | 0 | Slovenia | SI-131 |
| Trzin Municipality | 0 | Slovenia | SI-186 |
| Tukums Municipality | 0 | Latvia | LV-099 |
| TUL | 0 | Russia | RU-TUL |
| Turnišče Municipality | 0 | Slovenia | SI-132 |
| Tuscany | 0 | Italy | IT-52 |
| Tuzla Canton | 0 | Bosnia and Herzegovina | BA-03 |
| TVE | 0 | Russia | RU-TVE |
| TWH | 0 | United Kingdom | GB-TWH |
| TX | 6.25 | United States | US-TX |
| TY | 0 | Russia | RU-TY |
| Tyrol | 0 | Austria | AT-7 |
| TYU | 0 | Russia | RU-TYU |
| U | 0 | Ireland | IE-U |
| UA-40 | 0 | Russia | RU-UA-40 |
| UD | 0 | Russia | RU-UD |
| Uherské Hradiště | 0 | Czech Republic | CZ-722 |
| UKM | 0 | United Kingdom | GB-UKM |
| Ukmergė District Municipality | 0 | Lithuania | LT-53 |
| Ulcinj Municipality | 0 | Montenegro | ME-20 |
| ULY | 0 | Russia | RU-ULY |
| Umbria | 0 | Italy | IT-55 |
| UN | 0 | Moldova | MD-UN |
| Una-Sana Canton | 0 | Bosnia and Herzegovina | BA-01 |
| Upper Austria | 0 | Austria | AT-4 |
| Upper Normandy | 0 | France | FR-Q |
| Uppsala County | 0 | Sweden | SE-C |
| UR | 0 | Switzerland | CH-UR |
| Ústecký kraj | 0 | Czech Republic | CZ-42 |
| Ústí nad Labem | 0 | Czech Republic | CZ-427 |
| Ústí nad Orlicí | 0 | Czech Republic | CZ-534 |
