Yes, you must pay for buses in Paris in 2026; there is no free public bus system for adults. The standard fare for a single Bus-Tram ticket is €2.05 as of January 2026, though this can be reduced to €1.64 if you use the "Navigo Liberté+" postpaid system. In 2026, Paris has largely transitioned to a paperless environment; you are expected to use a Navigo Easy card or your smartphone (via the Bonjour RATP app) to "tap in" when boarding. You cannot buy a ticket from the driver anymore, a policy that was solidified to speed up boarding times. If you are caught without a validated ticket by the RATP inspectors, who frequently board at major stops, you will face an immediate fine starting at €50. For tourists, the Navigo Day Pass (€12.30) or the Paris Visite pass is often the most cost-effective way to use the buses, as it allows for unlimited transfers between the Metro and the bus network, provided you validate your digital ticket at the start of every journey.