<![CDATA[ABSTRACT The taxation sector is among the most intensive domains of government administration in issuing administrative decisions (Keputusan Tata Usaha Negara/KTUN), ranging from tax assessment notices to active collection measures, all of which must originate from and be exercised within the limits of authority set by Law Number 30 of 2014 on Government Administration (the Government Administration Law). The tiered delegation structure of tax authority, on one hand, creates room for decisions that exceed authority as regulated in Articles 17 and 18 of the Government Administration Law; on the other hand, the change in the tax judiciary's institutional architecture following Constitutional Court Decision Number 26/PUU-XXI/2023 makes the jurisdictional boundary between the Tax Court and the State Administrative Court (PTUN) in reviewing such decisions increasingly urgent to clarify. This article employs normative legal research using statutory, conceptual, and case approaches applied specifically to the taxation sector to analyze the criteria and forms of tax-sector KTUN that exceed authority, and their legal consequences and review mechanisms. The findings show that a tax decision may be categorized as exceeding authority where it exceeds a time limit, exceeds territorial jurisdiction, or contravenes statutory provisions under Article 18(2) of the Government Administration Law, with a legal consequence that is textually invalid under Article 70 but should be treated as voidable (vernietigbaar) and remains binding until annulled through a competent forum, and a review mechanism whose competence is divided between the Tax Court for disputes over the amount of tax owed and the PTUN for authority-validity disputes outside that scope. Such a jurisdictional boundary is concurrent in nature and prone to overlap, as also found in jurisdictional disputes in other administrative sectors. Clarity in these criteria and review forums is essential to guarantee legal certainty for taxpayers while ensuring the accountability of tax authorities.]]>
