ISO 17025 surveillance and reassessment: how ISO/IEC 17025 accreditation is kept, visit by visit

How does the ISO/IEC 17025 accreditation cycle work?

The grant of accreditation opens a cycle rather than closing a project. From the decision onwards the accreditation body keeps checking that the laboratory still deserves the scope printed on its schedule: surveillance visits in the intervening years, then a reassessment that looks at the whole laboratory again before the cycle renews. ANAB describes the same pattern plainly: once accredited, laboratories enter a cycle of surveillance and reassessment.

ISO/IEC 17025 itself sets no interval. The standard says what a competent laboratory must do; the accreditation body, working to ISO/IEC 17011, decides how often it looks. So two laboratories accredited to the same edition can face different calendars. Sterling does not accredit; your accreditation body plans the visits, assesses and decides whether accreditation continues.

Surveillance and reassessment intervals by accreditation body

The table shows only what each body states on its own site. For any other body, the interval is set in its published accreditation rules and your accreditation agreement.

Note the UKAS first visit: six months after the grant arrives before most laboratories have settled into a post-grant routine.

What a surveillance visit looks at

A surveillance visit is shorter than the initial assessment and samples the scope rather than covering all of it. The body decides the sample, so treat this list as preparation advice, not any body's rules. Be ready to show:

• closure and effectiveness of the corrective actions raised at the last visit;
• proficiency testing and interlaboratory comparison results since then, including what was done about any unsatisfactory result;
• quality control data and trends for the methods sampled;
• the internal audit and management review carried out since the last visit;
• complaints and nonconforming work, and how each was handled;
• calibration status and intermediate checks for the equipment behind the sampled results;
• competence and authorisation records for staff performing the sampled methods, including anyone new;
• reports issued under the accreditation, and correct reference to accredited status on them.

Assessors may also watch tests or calibrations being performed again, especially where methods, staff or equipment have changed. Findings from a visit are handled as at the initial assessment, with a deadline set by the body; ISO/IEC 17025 nonconformities: findings, corrective action and closure explains the response.

What reassessment re-examines

Reassessment is closer in depth to the initial assessment than to a surveillance visit. The body looks again at the laboratory against all of ISO/IEC 17025, across the full scope of accreditation, normally with a lead assessor and technical assessors for each discipline. Methods never sampled during surveillance come back into view, and the assessors can read the whole cycle's record: proficiency testing performance, recurring nonconforming work and whether corrective actions worked.

Three things tend to make reassessment harder than it needs to be. Validation files written for the initial assessment were not updated when a method changed. Uncertainty budgets still use the reference standards or ranges of three years ago. And the scope on the schedule no longer matches what the laboratory does, with tests quietly dropped or ranges drifted. Reviewing the schedule line by line against current practice a few months before reassessment removes most of that risk. The detail of the on-site visit itself is covered in The ISO/IEC 17025 assessment: document review, on-site assessment and witnessing.

Which changes should you tell the accreditation body about?

Each body's rules list the changes an accredited laboratory must notify, and the list is part of what you agree to at grant. Ask for it in writing and keep it with the management system. Changes that deserve a check against that list the week they happen include:

• ownership, legal entity or name;
• the technical manager or other key technical staff;
• premises, relocation or a new site;
• major equipment or reference standards behind accredited results;
• methods on the schedule, including a new edition of a standard method;
• tests or calibrations the laboratory stops performing.

New work is a separate route. A test, range or site that is not on the schedule is not accredited, however competent the laboratory is at it; it joins the scope through an extension, which the body assesses before adding it. Some bodies offer flexible scopes with their own limits, which ISO/IEC 17025 scope of accreditation: fixed, flexible and how to write it explains. Planning extensions to coincide with a scheduled visit usually keeps the extra assessment effort down, subject to the body's agreement.

Keeping the laboratory assessment-ready between visits

A laboratory that prepares only in the month before a visit shows it. A fixed annual rhythm produces the evidence as a by-product of normal work.

Some bodies set their own proficiency testing expectations; ANAB, for instance, requires laboratories to take part annually. The detail sits in Proficiency testing and interlaboratory comparison under ISO/IEC 17025, while ISO/IEC 17025 internal audit: the technical clauses and ISO/IEC 17025 management review: inputs, outputs and the record cover the other two annual anchors.

New editions and the move to Global ACI

No edition change is running for laboratories. ISO/IEC 17025:2017 is current, ISO confirmed it at systematic review in 2023, and no amendment or revised edition has been published, so no surveillance or reassessment visit will be testing a transition today. If a new edition is published, rely on ISO and your body for the transition, not on rumour.

What has changed is the recognition arrangement. On 1 January 2026 ILAC and IAF combined into Global ACI, whose MRA replaced the ILAC MRA, and existing accreditations continue to be recognised while arrangements transition. Ask your body how it wants accredited status and any combined marks shown on reports during that transition. Laboratories using Option B, where the management system meets ISO 9001, should also follow their certification body's arrangements for ISO 9001:2026, published on 16 September 2026.

How Sterling supports the accreditation cycle

Accredited laboratories rarely lose ground in one visit; they drift, one skipped proficiency testing round or informal authorisation at a time. Sterling's Sustain™ support is built to catch that drift early.

If you need to confirm what another laboratory's accreditation actually covers, How to verify a laboratory's ISO/IEC 17025 accreditation and scope shows where to look.

ISO/IEC 17025 surveillance and reassessment: questions buyers ask