From January 1, 2025, a one-way ticket costing €2.50 will replace the current fares for all metro, RER and regional train journeys in Paris and the Île-de-France region, regardless of the number of zones crossed. The new fare simplifies the system by reducing the number of existing combinations, making transport more accessible and easier to understand. Will the old tickets still be usable? How can you pay the lowest fare? We take a look. Airport tickets