This paper presents the development and validation of a questionnaire-based model to assess the quality of services provided by public institutions based on internal service variables. This model comprises four latent factors (Systems, Human Resources, Regulation and Relationship) that allow analyzing a set of 19 managerial variables involved in the perception of quality from the point of view of managers. The developed methodology was based on an empirical study that was statistically validated for the Brazilian federal public services, with the collaboration of the Digital Government Secretariat of the Ministry of Economy, which carried out a data collection survey with 289 services from 52 Brazilian public institutions. The model allows a standardization in the planning of the internal processes of the public services offered, with vision and administrative rationalization strategies to be adopted to optimize the quality offered by the services.