This study examines the impact of tax audits and investigations on tax compliance among Nigerian firms. Utilizing a comprehensive survey methodology, data was collected from 100 respondents, analyzed using percentage tables, and subjected to a one-sample t-test to test the hypotheses.

The findings reveal a significant positive relationship between tax audit procedures and the enhancement of tax compliance, with audits improving the accuracy of tax reporting and reducing tax evasion. Tax investigations were found to significantly instill fear and caution among taxpayers, leading to increased compliance, and effectively uncover instances of tax fraud, recovering lost revenue. The combined approach of tax audits and investigations was shown to build public trust and confidence in the tax system, ensuring comprehensive compliance. These results align with theoretical frameworks such as the Economic Deterrence Theory and the Audit Lottery Theory. Based on the findings, recommendations include regular and comprehensive audits, strengthened investigative mechanisms, an integrated enforcement approach, public awareness campaigns, and policy enhancements to improve tax compliance and fraud detection in Nigeria.