<![CDATA[The implementation of the Core Tax Administration System (Coretax) by the Directorate General of Taxes on January 1, 2025, pursuant to Minister of Finance Regulation No. 81 of 2024, marks a fundamental paradigm shift in Indonesia’s tax ecosystem. This change is structural in nature: it reduces information asymmetry between tax authorities and taxpayers through digital data integration, pre-populated tax returns, and automated risk-based monitoring. This article aims to analyze the implications of Coretax on corporate taxpayers’ tax planning strategies and to formulate a strategic adaptation framework for taxpayers, tax consultants, and corporate tax functions. Using a conceptual literature review approach synthesized with official data from the Ministry of Finance and the Directorate General of Taxes for the year 2025, this article proposes the concept of “Monitored Assessment” as an original conceptual framework describing an administrative phenomenon within the DGT’s supervisory function—not a change to the legal system of tax collection itself—in which taxpayers’ returns, filed independently under the self-assessment principle that remains formally in force, are increasingly cross-validated by a system whose data access, while still limited to certain data categories such as withholding-slip (bukti potong) and input VAT invoice data, is more comprehensive than under the previous system. This concept is rooted in the OECD’s cooperative compliance framework and Tax Administration 3.0, but integrates the specific context of Indonesia’s tax digitalization. This article argues that Coretax does not narrow the scope for legitimate tax planning but rather shifts its optimal point from downstream tax calculations to upstream data governance. Three conceptual propositions are formulated as an agenda for future empirical research. This article contributes a conceptual framework for tax adaptation in the Coretax era that can be tested through subsequent empirical research.]]>
