Expanding services always entails costs. The 4th phase of expansion will be part-financed by the Canton of Zurich, but also by federal government and the neighbouring cantons.

The 4th phase of expansion of the Zurich S-Bahn is part of an overall package of different rail infrastructure projects (Future Development of Railway Infrastructure, connection to the central European high-speed transport network and long-distance, regional and freight transport plans) The total cost of these additions amounts to around CHF 1 billion.

The costs of the railway facilities directly attributable to the 4th phase of expansion total around CHF 350 million as per the current stage of the project. Due to the territorial allocation of costs, around CHF 250 million of the investment amount is allocated to the territory of the Canton of Zurich. Half of these costs will be incurred for the first two stages by December 2015, the other half for the third stage by December 2018. The federal government will share the cost of 35 to 40% of the canton's contribution. The neighbouring cantons will also participate in financing various things.