The success of electronic filing services largely depends on their continuance usage. This study examines the factors affecting the continuance usage intention of the online tax filing services in Mauritius. An integrated model comprising Trust Theory and Information System Success Model (ISSM) is applied to assess the continuance usage behaviour of e-filing systems. The model has been extended by adding two additional variables: Perceived Usefulness and Perceived Risk. The model was tested using a sample of 315 users of e-filing services in Mauritius. A structural equation modelling technique using partial least square structural equation modelling verified the hypotheses. The results reveal that the continuance usage intention of an electronic tax filing system is influenced by Perceived Usefulness, User Satisfaction, and Service Quality. However, Perceived Risk does not influence the continuance usage intention of e-filing systems since the importance of Perceived Risk diminishes as trust in the e-service provider increases. The theoretical and practical implications derived from the findings of this study are also discussed.