Towards a Pan-African Economic Union? A Multimethod Study of Tax Harmonization

This study examines de jure tax harmonization across seven main-pillar African Regional Economic Communities (RECs) and three subcommunities based on selected tax features of thirty-three countries with overlapping memberships. It offers a three-tiered methodological framework: (1) feature-based identification of the current state of tax harmonization through comparative legal analysis; (2) quantification of these findings through a leximetric approach that adapts the Herfindahl-Hirschman Index (HHI); and (3) complementary text based analysis using natural language processing (NLP) to assess whether textual similarity patterns correspond to leximetric results. This approach provides a normative and scalable framework for analysing tax harmonization in multi-country samples. Comparative legal analysis indicates strong structural similarities across Africa in tax rates, anti-avoidance rules, and property and wealth taxes, while harmonization remains limited in residence criteria, tax incentives, and excisable products. The analysis also identifies several intra-community outlier countries such as the Democratic Republic of the Congo, Equatorial Guinea, Madagascar, Mauritius, and Nigeria. The leximetric analysis shows that the degree of harmonization is highest in the West African Economic and Monetary Union (WAEMU) (0.72), while it is lowest in the Southern African Development Community (SADC) (0.53). By tax type, convergence is strongest in value-added taxes and property and wealth taxes and weakest in excise taxes. These findings point to at least a moderate level of harmonization in each regional community. They also show that supranational instruments whose depth varies across African regional communities contribute to harmonization but do not constitute the sole driver. The text based analysis is broadly consistent with the leximetric ranking, yet it systematically overestimates the degree of harmonization. This indicates that text based methods can complement but not replace feature-based comparative legal analysis.