As of January 1, 2025, the ticketing system in Paris has been significantly simplified, but the answer is more nuanced than before. The old "Ticket t+" has been discontinued and replaced by two distinct options. If you are using the "Metro-Train-RER" ticket (€2.50), it is valid for a single journey across the entire rail network regardless of the zone, including transfers. If you are using the "Bus-Tram" ticket (€2.00), it is valid for the surface network. However, you cannot use the same single-use ticket to transfer between a bus and the metro. If your journey requires both, you must use two separate tickets. For most 2026 travelers, the best solution is the "Liberté+" pass, which is a "pay-as-you-go" system on a Navigo Easy card. With Liberté+, you are only charged for what you use, and it does allow free transfers between the rail and surface networks (metro to bus) within a 90-minute window, provided you don't use the same line twice. This digital transition makes the Liberté+ the "gold standard" for seamless travel across the French capital.