The GreenDIGIT project accelerates the transition to sustainable digital Research Infrastructures (RIs) by providing tools, methodologies, and guidance to assess and mitigate environmental impacts across the full lifecycle of digital infrastructures. This deliverable, D8.1, introduces the GreenDIGIT Self-Assessment Questionnaire as a practical instrument enabling RIs to evaluate their current sustainability performance and identify opportunities for improvement The questionnaire is structured to benchmark RI practices against key sustainability dimensions, including climate change mitigation, energy efficiency, resource use and circular economy, water and marine resources, pollution, and biodiversity. It integrates relevant European policies and regulatory frameworks—such as the Corporate Sustainability Reporting Directive (CSRD), the European Sustainability Reporting Standards (ESRS), the Ecodesign for Sustainable Products Regulation (ESPR), and the Energy Efficiency Directive (EED)—ensuring that RIs can align their operations with evolving compliance obligations. By offering a user-friendly and structured approach, the GreenDIGIT Self-Assessment Questionnaire not only supports compliance but also promotes continuous improvement. It provides RIs with actionable insights to strengthen sustainability strategies, enhance transparency, and contribute meaningfully to Europe’s green and digital transition. The questionnaire can be found online at: https://uva.data.surfsara.nl/index.php/s/pJxHsdeakKQfL70 using the password GreenDIGITD81Questionnaire! [This deliverable is pending approval from the European Commission]