The organisation of urban public transport is the responsibility of the local authorities, which set the fares. As fare revenues are not sufficient to cover all costs - they only account for 41% of operating expenditure, excluding investment - they supplement funding by other means. To do this, municipalities – grouped together in inter-municipal bodies such as metropolises, conurbation communities or urban communities - can levy a tax on the payroll of local employers, known as the mobility tax, and/or use their general budget, financed by local taxpayers. For a number of years, local authorities have favoured a policy of fare moderation, which has led to a gradual disconnect between fares and the actual use of transport services and therefore the costs incurred, and has encouraged the financing of public transport through taxation. This reduction in the contribution made by users to the financing of public transport jeopardises future investment, which is nonetheless necessary to meet mobility needs and environmental objectives. The report by the Cour des comptes, which responds to a request made on its citizens’ platform, addresses the issues involved in the development of urban public transport and its financing. The audit, which covers the main transport authorities, describes changes in contributions to the financing of public transport, particularly from users, and examines the operational and financial impact of fare moderation or free travel policies. To this end, it summarises a number of studies carried out by the financial jurisdictions and two surveys of users of the Montpellier and Lyon urban transport networks.