It’s complex, but here’s a popular short answer in the form of “auditor questions”:

• Are the processes properly documented and operating within the requirements of the Standard?
• Are quality policies effectively communicated internally and externally to you suppliers and outsources?
• Do the records and objective evidence substantially demonstrate that the QMS is effective?
• Are the procedures for assessing process effectiveness validated?
• Are measuring and monitoring processes of your QMS indicate that Quality Objectives are being met?
• Are the procedures for Control of Documents, Control of Records, Control of Non-Conforming Products, Corrective Actions and Preventive Actions effective?
• Are the internal auditing and management review procedures effective and can you demonstrate continual improvement?

Always insist on an ISO Certification issued by an ACCREDITED Registrar