Chemicals in the EU are mainly regulated based on their intended use. Each legal framework consists of requirements and guidance for hazard- and risk assessment, along with the associated decision processes e.g., registration or authorisation of chemicals for market access in the EU. As a single chemical may have multiple uses, it may be assessed under more than one framework, potentially leading to different assessment outcomes. To address this, the European Commission has introduced the ‘one substance, one assessment’ approach as part of the Chemicals Strategy for Sustainability. The aims of the approach include streamlining risk assessment processes and reducing duplication of work in assessing the same chemical. This study aimed to map the scope of chemicals subject to assessment in multiple legal frameworks and to illustrate the importance of coordination and communication in chemical assessment processes. This was achieved by identifying chemicals that are either registered or have received specific approval for the EU market, and analysing their presence in different legal frameworks. Our findings showed that almost one-tenth of the substances identified were listed under more than one framework. However, there was a notable lack of coherent chemical identifiers available to accurately identify chemicals across the frameworks. Additionally, we identified the presence of phthalates, bisphenols and PFAS in EU frameworks to illustrate how a group-based approach to chemical assessment could be applied across different legal frameworks.