The EU Taxonomy Regulation relies on sustainability reporting to channel financial resources to sustainable activities. Financial institutions are key actors in the Taxonomy setting because they operate as financial intermediaries and have a dual role as both users and preparers of sustainability information. This paper investigates the perceived uncertainty that characterizes the sustainability reporting regulatory environment of a particular type of financial institution, banks, to identify the elements that generate that perception. Drawing on literature on regulatory uncertainty, this paper conducts a case study of the Spanish banking industry informed by interviews and complemented by other data sources. The analysis unveils two significant elements driving regulatory uncertainty: the Taxonomy’s lack of clarity regarding the operationalization of its measures and rules and the timeline and oversight of its implementation. The study also documents that the Taxonomy induces uncertainty in the non-regulatory environment due to its unpredictable impact on banks’ reputation and market competition, as well as to the changes it provokes in banks’ internal structures and processes to address regulatory requirements. As the perception of regulatory uncertainty represents an impediment to compliance, understanding the elements giving rise to it can help to mitigate such perception and facilitate the fulfillment of regulatory demands. This investigation offers implications for policy and practice to facilitate the production of the sustainability information banks must disclose according to the EU Taxonomy, particularly the green asset ratio.
