This paper, written in collaboration with EGIAN, explains what supply chain due diligence is and how supply chain assurance works. We interviewed members to understand how they help businesses to manage supply chains. Our interviews show that accountancy firms, including small and medium-sized accountancy networks and associations, are increasingly prepared to review the sustainability of supply chains. We discuss market practices with three expert representatives of smaller accountancy firms. We consider what is needed for reliable and robust assurance on the supply chain,
including:

• common standards and methodologies for high quality assurance
• the qualities, expertise, capabilities and skills assurance service providers need
• ethical requirements, including independence standards

This reveals a market trend for professional accountants, from firms of all sizes, to support businesses with the application of due diligence requirements.