If the VAT rate of 0% applies to an event, the description "Prices incl. VAT" is still correct. The presentation is independent of whether the event is subject to VAT or not.
In Switzerland, it is the organiser's responsibility to check whether their event is subject to VAT and to pay the corresponding taxes to the state. Regardless of whether VAT is applicable, we only indicate to ticket purchasers with the note "Prices incl. VAT" that no additional taxes are levied on the ticket. This means that the price shown to ticket buyers is complete and inclusive.
