ISO 17025 accreditation process: the twelve steps from scope to published schedule

How the ISO 17025 accreditation process works

Three parties take part, each with a separate job. The laboratory designs, runs and answers for its management system and its technical work. A consultancy such as Sterling helps the laboratory prepare: it scopes, plans, builds and checks, but it plays no part in the accreditation decision. The accreditation body, which itself operates to ISO/IEC 17011, examines the laboratory and decides whether to grant accreditation and for exactly what.

Accreditation attests competence to produce particular results, so the assessors are specialists in the disciplines on your scope and judge the work itself, not only the paperwork. The outcome is a certificate and a published schedule of accredited activities, whose international acceptance rests on the Global ACI arrangement that replaced the ILAC MRA on 1 January 2026.

Steps 1 to 5: the laboratory's side of the process

Step 1: decide the scope and the reason

Start with who needs your results accredited: a regulator, a customer contract, a tender or an export market. That decides which tests or calibrations and sites matter, and whose accreditation will be accepted. Put on the first application only the methods you can defend with evidence by the assessment date. The scope of accreditation guide covers how the schedule is worded.

Step 2: gap analysis

Sterling's gap analysis reviews the laboratory against clauses 4 to 8 of ISO/IEC 17025, method by method, and turns the result into an action list with owners and dates. It is an engagement stage, carried out by consultants with your staff. It is not the free online readiness check, which is a self-assessment, and it is not the pre-assessment some accreditation bodies offer much later.

Step 3: build the technical evidence

This is the longest stretch of work: standard methods verified, in-house or modified methods validated, uncertainty evaluated, equipment calibrated with traceable certificates, and staff formally authorised for each method. The guides on method validation, measurement uncertainty and equipment and calibration explain each of these in depth.

Step 4: operate, and take part in proficiency testing

Assessors expect a laboratory that has been working to its procedures for a while, with quality control data and technical records to show for it. Proficiency testing or interlaboratory comparison results, and the actions taken on any unsatisfactory result, are among the first things an assessor asks for; because rounds follow the provider's calendar, register early.

Step 5: internal audit and management review

Before applying, audit the whole laboratory, including the technical clauses, witness a sample of tests or calibrations yourselves, and close what the audit finds. Then hold a management review that looks at the results and decides. Both records go into the application pack, and the assessors will read them closely.

Step 6: choose the accreditation body and apply

Most laboratories apply to their national accreditation body, such as UKAS in the United Kingdom, NABL in India, PAB in the Philippines or EIAC in Dubai. Check its Global ACI MRA signatory status for your scope, its assessors for your disciplines and whether customers or a regulator name a body. The guide to choosing an accreditation body takes you through those checks.

An application usually consists of the body's form, the application fee, the proposed scope and the management system documents. The body checks the application and a lead assessor is appointed. Apply once the build is well advanced, since the body's queue and assessor availability then set the pace.

Steps 7 to 9: document review, pre-assessment and on-site assessment

The table shows what the body typically does after it accepts your application. Terms and order vary by body. The assessment guide describes the on-site days in detail.

Witnessing is the step laboratories underestimate. An assessor may ask an authorised analyst to run a method, then trace a finished result back through raw data, equipment, calibration status, reference material and authorisation. Every link must hold.

Steps 10 and 11: corrective action and the accreditation decision

Findings raised at the assessment have to be answered with root cause, correction and corrective action, supported by evidence, within the period the body sets. UKAS allows approximately twelve weeks to provide suitable evidence for mandatory findings; the NABL FAQ states 30 days. The nonconformities guide explains how findings are written and closed.

Once the findings are closed, the assessment team's recommendation goes to the body's decision stage: an accreditation committee at NABL, a panel of the Accreditation Council at A2LA, and an equivalent function at other bodies. If accreditation is granted, you receive a certificate and a schedule that the body publishes. Read the schedule the day it arrives; a method, range or site you expected but cannot see there is not accredited.

Step 12: surveillance, reassessment and extensions

Accreditation is kept, not held. The body returns for surveillance visits, usually once a year, and carries out a full reassessment on a cycle it sets. UKAS is a useful reference: its first surveillance visit takes place six months after the grant, surveillance is annual after that, and reassessment comes every fourth year. Other bodies set different validity periods and reassessment intervals, so confirm the cycle in the body's own rules. New methods reach the schedule through extensions, assessed like the originals. The surveillance and reassessment guide covers the cycle.

How long the ISO 17025 accreditation process takes

Expect six to twelve months from gap analysis to decision for a first accreditation, most of it on the laboratory's side. The body's part alone varies with preparedness: A2LA reports about five months on average for new applicants and EIAC one to three months. The timeline guide gives the stage-by-stage calendar.

Five mistakes that stall accreditation

• Applying with every method at once. A wide first scope multiplies validation, uncertainty and witnessing effort; a focused scope followed by extensions is usually faster.
• Treating the management system as the whole job. Tidy procedures do not survive a witnessed test performed by an analyst who has never been formally authorised.
• Leaving proficiency testing too late. Rounds follow the provider's calendar, so a missed round can push the application back.
• Calibration certificates that do not establish traceability. Check the provider's accreditation and the certificate content before the assessor does.
• Slow answers to findings. Line up who writes the root cause analysis before the assessment ends.

ISO 17025 accreditation process: questions buyers ask