This methodological note describes the approach developed by the European Forest Institute (EFI) to create a tool supporting legality due diligence for EUDR compliance in agricultural supply chains. The tool is based on mapping relevant national legal requirements, refining them for EUDR relevance, and developing proportionate due diligence recommendations. The methodology emphasises stakeholder engagement, consensus-building, and adaptability to national contexts. It includes guidance on assessing implementation, verification, and the role of certification. The tool is designed as a living document, to be tested, updated, and used by operators, authorities, and civil society to facilitate compliance, transparency, and risk management in supply chains.