There is only one tunnel that is charged in Andorra. It is called Túnel d’Envalira and it runs between Pas de la Casa (near border with France) and Grau Roig (Andorran ski resort).
The fee for the passage of the d’Envalira tunnel is €6.80 for passenger vehicle.
We could not find more information about method of payment, so we ask you to have this amount in cash prepared.
If you are interested in other information about Andorra, we recommend this official tourist page: