DOI: 10.36347/sjebm.2020.v07i09.001

Pages: 286-292

The major objective of this study is to determine the impact of the self-assessment system of taxation on tax revenue in Nigeria. It was prompted by the major change and liberalisation in self-assessment system of tax administration in Nigeria in 2011. The study employed ex post facto experimental design to evaluate the difference in tax revenue before and after SAS implementation. It covered a period of 16 years, 2003 to 2018, eight years each of pre and post implementation of the system in Nigeria. Secondary data were obtained from Central Bank of Nigeria statistical bulletin and from the website of Federal Inland Revenue Service. Three research questions and two hypotheses were formulated to guide the study. Tax/GDP ratio and actual/target tax collection ratio were used to measure the efficiency of this system of taxation. The results of the analysis indicate a post- SAS (2011 to 2018) tax/GDP mean value of 5.07% lower than pre-SAS (2003 to 2010) tax to GDP ratio of 6.23%. Similar results were obtained using actual/target tax collection ratio. Further analysis, using paired sample t-test for pre and post SAS period tax/GDP ratio at 95% confidence level found this difference to be statistically insignificant, t (7) = 1.819 < 1.895 and the p-value was 0.112 > 0.05. It is therefore concluded that Self-Assessment System of taxation has a negative but insignificant effect on tax revenue in Nigeria. Since the efficiency of SAS has been well documented in several empirical studies in other countries, this study recommends a further review of the Self-Assessment Regulation 2011 to explore other means, in conjunction with the SAS, of improving efficiency of tax collection in Nigeria.