This study investigates the influence of attitudes toward Coretax, its adoption, isomorphic pressures, and perceptions of tax fairness on tax compliance in Indonesia. The objective of this research is to explore the acceptance of Indonesia's newly implemented electronic tax system, Coretax, among taxpayers who have used it. A quantitative cross- sectional methodology was employed, with data gathered through an online survey of 204 respondents involved in business operations. The findings reveal a negative relationship between attitudes toward Coretax and tax compliance, challenging previous studies that typically reported a positive association. In contrast, the study highlights that Coretax adoption, isomorphic forces, and perceptions of tax fairness are positively related to tax compliance. These results offer important implications for policymakers in the development of electronic tax systems, stressing the need to consider system usability, social influences, and fairness perceptions to improve tax compliance. This research is the first to concurrently examine these variables in the context of attitudes and adoption of Coretax after its recent roll-out in Indonesia. Limitations of the study include its focus on the early phase of Coretax adoption, reflecting primarily the initial perceptions of users rather than long-term impacts. Future research could explore the long-term effects of Coretax and expand the scope to compare it with previous systems.