On-site assessment examinations are carried out by audit teams. Each team consists of a team leader and at least one specialist. The number of specialists depends on the number of specialised activities for which the laboratory has applied for accreditation. Specialists are persons with practical experience, and a specific expertise in the field in which a laboratory wishes to be accredited. The members of the audit team are also referred to as auditors.

The auditor will verify on-site whether the quality system complies with the stated standards and whether it operates in conformity with the quality documentation. He must form a general impression of the competence of the workplace or department. This may be by observing processes in action, interviews with the management and personnel, and reviewing the quality documentation. The assessment – the audit – is entirely of an independent nature. The auditors guarantee this, and are themselves not involved in the laboratory in question.

The CCKL auditors have undergone training as a Quality and Assessment Specialist. This training is not available to everyone. Nominees and applicants are submitted via the professional associations. Auditors are also expected to attend auditor meetings.