This study examined tax enforcement measures and revenue optimization in States’ internal Revenue Service in Nigeria. The research adopted descriptive survey research design. The population for this study was five hundred and seventy-six senior staff across the State internal Revenue Service in Nigeria and a sample size of two hundred and thirty-six senior staff of State internal Revenue Service in Nigeria. The study used questionnaire instrument, and data were analyzed in the Statistical Package for Social Sciences. The research questions were analyzed using mean and standard deviation and hypotheses were tested using Simple bivariate regression analysis at a significance level of 0.05. The results of the findings showed that there is a positive significant relationship between litigation and measures of revenue optimization in Nigerian States. It was further revealed that there was a strong positive significant relationship between power of distrain and the measures of revenue optimization in Nigerian States. Furthermore, the study also revealed a strong positive significant relationship between search and seizure and the measures of revenue optimization in Nigerian States. Therefore, the study concludes that there is a strong positive relationship between tax enforcement measures and revenue optimization. The study recommends that litigation support should be adopted by State internal Revenue Service in Nigeria as it will enhance the payment of tax by the taxpayers. Tax penalty should be stiff enough to serve as deterrent to would-be tax defaulters; also, power of distrain should be encouraged. Search and Seizure is appropriate when a crime is suspected and therefore will enhance revenue optimization if adopted. Judicious use of taxpayer’s money should be made and be seen to have been properly utilized. This will encourage taxpayers to continue to pay taxes
Victor Eniema Essiet (Wed,) studied this question.