ISO 17025 assessment: what happens in the document review, the on-site assessment and witnessing

What is an ISO/IEC 17025 assessment?

It is the accreditation body's examination of whether your laboratory is competent to produce the results named on your application. The body works to ISO/IEC 17011, the standard for accreditation bodies, and it assesses rather than audits: the question is not only whether procedures exist and are followed, but whether the people, equipment, methods and calculations behind each reported number can be trusted.

Three activities make up an initial assessment. The body first reviews what you submitted with the application. Many bodies then offer a pre-assessment, which you may decline. Finally a team visits the laboratory, examines the management system and the technical records, and watches work being performed. There is no Stage 1 or Stage 2 and no certification body; that vocabulary belongs to management system standards.

This guide covers what happens inside those three activities. The route from scoping to the decision is set out in the accreditation process, step by step, and selecting the body in choosing an accreditation body.

Document review: what the body reads before it visits

The application is more than a form. It carries the proposed scope of accreditation, meaning the tests or calibrations, methods, ranges and sites, together with the documents that show how the laboratory meets clauses 4 to 8. Reviewers use them to decide whether a visit is justified yet and which technical assessors it needs.

The reviewer may come back with questions or ask for missing evidence before scheduling the visit. Treat those requests as early findings: answer them fully rather than promising the evidence on the day. Which records each clause needs is covered in the documentation guide.

Is a pre-assessment worth it?

Several bodies offer one. UKAS describes it as an informal visit before the initial assessment to gauge how ready you are, and A2LA and NABL also list a pre-assessment as an option in their process. Nothing in it leads to a decision.

A pre-assessment earns its cost when the scope is technically broad, when the laboratory has never been assessed before, or when you suspect a gap in traceability or validation but cannot tell how the body will view it. It adds less when an independent internal audit has already covered every technical clause.

The on-site assessment, day by day

The body sends a plan beforehand that names the team and the activities to be witnessed. The length depends on the number of methods, disciplines and sites; a single-discipline laboratory with a short scope may need a day or two, while a multi-discipline scope takes longer and may bring several technical assessors at once. The pattern below is typical of a two-day visit for a small testing laboratory.

Keep the people named in the plan free for the whole visit; assessor time spent waiting is time you pay for.

Witnessing: how assessors watch the work

ANAB puts it plainly: the laboratory demonstrates technical competence through method witnessing. A technical assessor asks an authorised member of staff to perform a method on the application, on a real item, a retained sample or a proficiency testing material, while they observe.

During the demonstration the assessor checks that the person follows the current version of the method, uses the equipment listed for it, records observations at the time they are made, and handles items and reference materials as the procedure says. Afterwards the assessor usually traces the result backwards: technical record, equipment calibration and traceability, environmental conditions, the operator's authorisation and the uncertainty applied. The technical records must let someone else reconstruct the result; witnessing is where that is tested.

Not every method is witnessed. The team samples, usually favouring methods that carry the most risk, those that are newly validated, and at least one from each discipline or technique. Choosing which methods go on the application is covered in the scope of accreditation guide; the method evidence itself in method verification and validation and measurement uncertainty.

Findings, corrective action and the decision

Each finding names the requirement, the evidence seen and why it falls short. Agree the facts at the closing meeting, and raise any disagreement then, with evidence. Findings are then answered in writing, normally with the cause, the correction and the corrective action, supported by records.

Deadlines differ. UKAS allows about twelve weeks to provide suitable evidence for mandatory findings, while NABL's guidance sets 30 days. How to analyse, write and close them is the subject of the nonconformities guide, and what assessors tend to ask in assessor questions.

Once findings are closed, the assessment team's recommendation goes to a committee or council at the body that did not take part in the visit. Accreditation is granted for the scope the evidence supports. The certificate and the public schedule follow, and surveillance begins; UKAS, for example, makes its first surveillance visit six months after the grant.

ISO 17025 assessment: questions buyers ask