The informal sector constituted a critical component of Uganda's economy, particularly within urban centres such as Kampala. This sector predominantly comprised small-scale enterprises, including those operating outside formal registration frameworks or relying primarily on manual, paper-based systems for transactional record-keeping. Despite their significant contribution to employment generation and local livelihoods, these enterprises often exhibited low levels of tax compliance, thereby constraining the government's efforts to mobilise domestic revenue effectively. In response to these challenges, the Uganda Revenue Authority (URA) introduced the Electronic Fiscal Receipting and Invoicing Solution (EFRIS) in 2021, aimed at enhancing transparency, streamlining tax administration, and reducing revenue leakages. While EFRIS principally targeted registered taxpayers, it was increasingly extended to informal and semi-formal businesses that previously operated without digital tools, requiring them to adopt electronic invoicing and fiscal devices. This policy initiative represented an effort to integrate such enterprises into the formal tax system and promote voluntary compliance. Accordingly, this study sought to examine the extent to which EFRIS adoption influenced tax compliance among informal sector operators in Kampala District, with a specific focus on businesses transitioning from manual to digital systems. The research thus situated the informal sector within the context of technological tax interventions, offering insights into both behavioural and systemic determinants of compliance.