Andorra is a co-principality — its heads of state are the Bishop of Urgell and the President of France, an arrangement running since 1278. In practical terms this produces a country that uses the euro without being in the European Union, and that has its own customs regime.
Getting there
There is no airport and no railway. Every arrival is by road. The usual approaches are from Barcelona (around three hours) and Toulouse (about three and a half); scheduled coaches run from both airports several times a day and are cheap and reliable. On the French side the nearest station is L'Hospitalet-près-l'Andorre, with a bus connection over the border.
If you drive, note that the Envalira pass tops out at 2,408 metres. The tunnel beneath it is tolled and worth using in bad weather. Winter equipment is compulsory when signposted, and rental cars from Spain or France should be checked for permission to cross the border.
Borders and allowances
Andorra is outside the EU customs union, so there are checks when you leave in both directions. Duty-free allowances on alcohol, tobacco, electronics and perfume are real and enforced, and the queues at the Spanish border on Sunday afternoons in winter can be long. Keep receipts for anything substantial. Passport or national ID is required; there is no visa regime of its own, but travellers needing a Schengen visa must be able to re-enter Spain or France.
Money and costs
The currency is the euro. Cards work everywhere. The local sales tax, IGI, is far lower than Spanish or French VAT, which is why fuel, alcohol, tobacco and electronics are cheaper. Accommodation and restaurants are not notably cheap, particularly in ski season.
Health and connectivity
The European Health Insurance Card is not valid here, since Andorra is not in the EU. Travel insurance is genuinely necessary, and should cover mountain rescue if you plan to walk or ski — helicopter evacuation is charged. Mobile roaming is operated by the national provider and EU roam-like-at-home rules do not apply, so check tariffs before arriving or you may return to an unpleasant bill.
Language
Catalan is the sole official language, and Andorra is the only country where that is the case. Spanish is universally understood, French is common in the north and towards the border, and English is spoken in the ski resorts and larger hotels but far less in the villages.