Increasingly, companies are obliged and incentivized to consider the impact of their business processes on the environment, to promote sustainable business practices. In particular, the EU Taxonomy for Sustainable Activities outlines criteria for when business practices contribute towards a sustainable future. However, it is unclear in how far existing methods for identifying, analysing, and improving business practices, in particular those of the disciplines of Business Process Management (BPM) and Green BPM (that is, a variant of BPM with a focus on environmental sustainability) can relate to those criteria and the concepts contained therein. Therefore, we develop and propose a metamodel that combines concepts of the EU taxonomy and Green BPM, and clarifies the relationship of the two frameworks. This metamodel increases conceptual clarity and allows practitioners to apply Green BPM approaches in light of the EU taxonomy, and researchers and tool providers to further explore technical solutions in light of the EU taxonomy. It provides a clear overview of how the gap between sustainability regulations and approaches for sustainable business practices can be bridged. We evaluate the semantics and pragmatics of our metamodel, and sketch potential applications with an illustrative example.