This release introduces a comprehensive R script that transforms a Multi-Regional Input-Output (MRIO) table into an Interregional Input-Output (IRIO) table for six Italian sub-regions: Northwest (NW), Northeast (NE), Toscana, Centro, Sud, and External (Ext). The script focuses on accurately representing interregional trade flows, allowing for detailed economic analysis and modeling. Key updates include the calculation of internal production by adjusting total flow matrices to reflect internally produced goods, the computation of interregional intermediate imports through detailed import matrices, and the integration of international imports into each region’s economic structure. Final consumption from internal production is calculated to differentiate between domestic consumption and imports, while interregional final exports are computed based on regional trade flows. Export flows outside Italy are preserved without affecting interregional dynamics. The script also includes comprehensive consistency checks that ensure the total resources, internal production, imports, and exports for each region align with expected values. This methodology transforms the MRIO table into a more granular IRIO table, providing essential input for both the Production and Final Demand modules of economic models. The release is designed to process 2019 MRIO data and interregional trade flows, enabling users to generate IRIO tables for advanced economic analysis. With improvements in accuracy, ease of use, and enhanced consistency checks, the script provides a reliable tool for understanding regional trade dynamics within Italy and supports researchers, economists, and policymakers in their analysis of regional economic behavior.