This article examines the contribution of the Integrated System for Financial Administration (SIAFI) of the Brazilian government to the promotion of horizontal accountability of the federal public administration in the perception of the system's distinct groups of users. Based on the theoretical framework and analysis of documents on the SIAFI and the rules on public administration, we defined three dimensions to assess accountabilitytransparency, rendering of accounts and attribution of responsibilityoperationalized through an online questionnaire with responses scored on a Likert scale. This questionnaire was sent to four groups of system usersmanagers, operators, control agents and investigation agentslinked to 128 entities of the federal government. The treatment and analysis of the results through factor analysis and comparison of groups allowed characterizing an overall perception of the efficacy of the SIAFI in promoting horizontal accountability, despite variations in this perception within the constitutive dimensions defined, according to the users' origin and their relationship with the system.