This study examined the impact of the Electronic Fiscal Receipting and Invoicing Solution (EFRIS) on the performance of small and medium enterprises (SMEs) in Kampala District, Uganda. Although EFRIS is mandatory, many SMEs primarily use the system for tax compliance, with limited understanding of its broader business benefits. Using a mixed-methods research design, the study targeted SMEs registered under the EFRIS system in Kampala District. A sample of 150 SMEs was selected through a combination of stratified and purposive sampling techniques. Quantitative data were collected using structured questionnaires and analyzed using descriptive statistics, Pearson correlation, and multiple regression analysis with the aid of Statistical Package for the Social Sciences (SPSS) Version 26. Qualitative data were gathered through semi-structured interviews with selected SME owners, managers, accountants, and Uganda Revenue Authority officers and analyzed thematically. The findings revealed that effective and integrated use of EFRIS significantly improves SME financial performance and operational efficiency. Ease of use and system accessibility were found to positively influence operational efficiency, while increased awareness of EFRIS functionalities significantly reduced tax compliance costs. The study concluded that EFRIS should be promoted not only as a tax compliance tool but also as a strategic business management system. Continuous training, improved system usability, and enhanced awareness campaigns by policymakers and tax authorities are recommended to maximize the performance benefits of EFRIS for SMEs.