This study addresses critical challenges in the reporting, monitoring, and use of energy audit data under Article 11 of the Energy Efficiency Directive across 18 EU member states. Current practices reveal significant variationsresulting in notable information loss regarding industrial final energy use, particularly in seven member states. This information loss poses challenges for supervisory authorities in evaluating policy and tracking energy efficiency progress, highlighting the pressing need for harmonized data practices.To tackle these issues, the study develops and validates a novel energy end-use taxonomy for the iron and steelindustry, using bottom-up data from five Swedish plants. Adopting the taxonomy concept enables process-levelreporting, reducing data compilation efforts, misallocation risks, while enhancing policy evaluation and development by avoiding double counting. Additionally, it introduces a standardized reporting template designed forbroader adoption, addressing the absence of minimum reporting criteria in the Energy Efficiency Directive. Theseadvancements shift resources from data compilation to policy-driven analysis and support cross-sectorcomparability.By harmonizing data reporting, the study highlights that integrating the taxonomy concept into reportingframeworks can significantly support the reporting and monitoring of energy audit data and boost the effectiveness of energy efficiency programs across the EU.