The Build-Operate-Transfer (BOT) scheme enables private investors to construct, operate, and subsequently transfer infrastructure facilities to the government after a specified period. Private participation in these strategic projects is formalized through a BOT agreement, which necessitates the professional involvement of both a Notary and a Land Deed Official (Pejabat Pembuat Akta Tanah – PPAT). However, there remains a legal ambiguity (normenvaag) regarding the appropriate form of the deed, specifically whether it should be a notarial deed or a land deed. This study aims to analyze the legal framework governing BOT agreements on state-owned land under Indonesian law, as well as to examine the legal framework and authority required for the transfer of buildings upon the agreement's expiration. Employing a normative legal research method, this study utilizes the theories of legal certainty, contract law, and legal authority as analytical frameworks. The results indicate that, under Indonesian law, BOT is classified as an unnamed contract (innominaat) governed by the general provisions of the Civil Code (KUHPerdata) and is obligatory in nature. The legal construction of a BOT agreement on state-owned land constitutes a legal relationship that integrates both contractual and property law aspects. Consequently, the expiration of the agreement must be understood not only as the termination of the contractual relationship but also as the formal transfer of the land and/or building objects back to the government, which requires the exercise of PPAT authority to ensure legal certainty.