Tax evasion is one of the most persistent challenges facing tax systems worldwide, closely linked to declining public revenues, weakened tax equity, and reduced governance efficiency. The present study aims to explain tax evasion on the basis of good governance indicators by simultaneously testing the direct effect, the mediating role of administrative corruption, and the moderating role of digital government within the General Directorate of Taxation of Mazandaran Province. Data were collected using a researcher-developed questionnaire whose face and content validity were assessed using Lawshe’s (1975) content validity ratio, and whose construct, convergent, and discriminant validity were tested in SmartPLS 4 using Partial Least Squares Structural Equation Modeling (PLS-SEM). The findings showed that good governance has a significant negative effect on administrative corruption and on tax evasion. Administrative corruption also showed a strong positive effect on tax evasion. Indirect-effect analysis confirmed the partial and significant mediating role of administrative corruption in the relationship between good governance and tax evasion. Furthermore, digital government, as a moderating variable, significantly weakened the intensity of the effect of administrative corruption on tax evasion. Consistent with recent international evidence on the moderating role of open and digital government in reducing tax evasion, these findings show that reducing tax evasion is not solely dependent on punitive deterrence tools; rather, improving the quality of governance, institutionally controlling administrative corruption, and investing in digital-government infrastructure can be employed as a complementary policy package for enhancing tax compliance.