This report features the main findings and lessons learnt from the development of the regional and municipal government finance databases (REGOFI and MUNIFI). The result of a joint OECD-EC project conducted between 2022 and 2024, it provides unique fiscal data at the aggregated and disaggregated municipal and regional levels. These databases aim to facilitate research and analysis on various policy areas such as public finances and decentralisation, health, climate, infrastructure, and social protection. The report begins by covering the development of the common methodology and taxonomy, in collaboration with National Statistical Institutes and other stakeholders. It continues by harnessing the comparable nature of the municipal and regional public finance data via analyses within and across countries. Finally, the report looks at next steps for the database, potential research and policymaking insights, and challenges associated with developing a database at this level of granularity, including addressing data availability, harmonisation, and capacity constraints.