<b>A performance evaluation approach for service providers under the integrated management system criteria</b>

This paper presents an innovative method for evaluating service provider performance through standards integration, including <b>ISO 9001:2015, ISO 20400:2017, and ISO 45001:2018</b>. It also presents a robust five-maturity framework designed to maximize effectiveness and establish essential indicators for supplier-buyer relationships. In addition, this paper emphasizes the critical role of sustainability in service contracting and draws on authoritative sources for performance assessment. Finally, the conclusions highlight the verification of qualitative variables through a case study, contributing to the knowledge base of sustainable development organizations.