Effective monitoring of national circular economy policies requires consistent, national databases of material flows and environmental impacts. Yet, databases and indicators developed so far are scattered and inconsistent. To tackle this problem, Statistics Netherlands (CBS) developed a material flow monitor (MFM) that integrates existing statistics using principles of the System of Environmental Economic Accounting (SEEA). The MFM is the physical counterpart of the Dutch supply and use tables (SUT) of the National Accounts and is also referred to as physical SUT (P-SUT). The P-SUT captures national resource extraction, product imports and exports, product flows between economic sectors, as well as emissions and waste streams resulting from economic activities. Our work illustrates how a statistical office can use and enrich its formal statistical data to compose an MFM consistent with the National Accounts and how indicators can be extracted with a case study on the bio-based economy. We contribute a clear step-by-step description of the method and the used datasets. This supports the development of MFMs by other statistical offices and researchers, thereby enabling consistent and comparable circular economy monitoring.