This study focused on the effects of tax systems on economic growth of Nigeria and South Africa SA, from (2001-2021). The study used Ex-Post Facto research design. The population of the study included all African countries; while the sampling methods embraced purposive sampling techniques that selected only Nigeria and South Africa because of the similarities in both countries tax systems and economic growth. Secondary data was used sourced from World Bank Data, CBN statistical bulletin, Federal Inland Revenue (FIRS) from Nigeria, and South African Revenue Services (SARS), from (2001-2021). The statistical tools applied was a cross-sectional multi-liner regression, which included pre-analyses tests such as: Descriptive Statistics, Pearson Correlation, Unit Root, Co- integration Test and Error Correction Model. After the analyses: the adjusted R-squared value for both countries respectively show that all the independent variables jointly have the power to explain about 78%, 58% of the systematic variation found in RGDP of Nigeria and South Africa, while the balance of 22%, 42%, are the stochastic elements in endogenous and exogenous variables affecting both tax system not captured in the study VAT is positive and non- statistically significant in Nigeria, while it is positive and statistically significant in South Africa; both Nigeria and South Africa. Stamp and excise duties are positive and non-statistically significant; again in Nigeria, CGT is negative and statistically significant, while in South Africa it is positive and non-statistically significant. Therefore, it is recommended that administrator of tax, can improved in tax collection and avoidance in both countries; the insignificant of VAT GDP can be avoided through transparency in administrations. Also, governments of both countries should encourage domestic and foreign operations to increase capital gain tax and ensure adherence on the withholding tax laws.

Keywords : Tax system Value Added Tax(VAT),Economic Growth, Nigeria and South Africa.