Most studies on tax research have focused on the developed countries, and those on developing countries concentrate on subjects of general application. As a result, research on many aspects of tax applicable to low-income countries (LICs) has been neglected. By presenting an in-depth analysis of Uganda’s tax system, this study seeks to address this gap. The authors analysed panel data spanning over seventeen years to identify the key system gaps. The findings revealed that Uganda’s tax system conforms to the generally accepted international standards, and its economic performance during the period was above the regional sub-Sahara Africa (SSA) average. However, tax revenue performance still remains poor. The main reasons include: unrealistic tax expenditures, corruption, poor governance, low tax morale, overdependence on international trade tax revenues, and structural system weaknesses. To address those challenges, mitigation measures including creating a firm and all-inclusive political settlement; enforcing anti-corruption measures; streamlining the tax system to eliminate system inefficiencies; and systematically formalizing the agricultural and informal sectors to widen the tax base are proposed. It is hoped that the findings provide valuable insights to tax policymakers in formulating policies for improving revenue performance in Uganda and related LICs.