This document describes the characteristics of a Common Transport Service Account System (CTSA). It presents the common transport service account framework and associated use cases. The objective of the CTSA role model is to cover relevant transport services, the payment methods, the account types where the user of the service is charged for the service and that requires a more overall role and responsibilities model. The model also defines external stakeholders that impact and border the model, that is, the general financial (banking) system. The framework assumes an account-based system where charges for services are calculated and charged in the account system. The main idea behind the CTSA framework is to provide a transport service user with the benefit of seamless acquisition of access rights to multiple transport services by multiple service / operator managers through a common transport account. This framework assumes a technology-agnostic front end with respect to the payment media and reading equipment. The focus of this framework is the back-office / account management system as a vehicle to integrate multiple transport services and managers.A new set of terms are introduced in this document to distinguish the convergence of a common approach for payment for transportation services from more traditional models using "smart cards" or electronic tickets. The model describes a move towards common or linked mobility accounts for all traveller payment needs, whether for parking, tolls, public transport and other disruptive mode options (e.g., bikeshare, carshare, microtransit, micromobility), inclusive of commercial payment and benefit models.