7 Common Nonconformities Found During ISO/IEC 17025 Assessments

Common issues identified during accreditation assessments and how laboratories can prevent them.

By Ashley Dennis • Laboratory Quality Systems Expert
Published March 8, 2026
Category: Laboratory Accreditation | ISO/IEC 17025
Reading time: ~4 minutes

Laboratories pursuing accreditation under ISO/IEC 17025 must demonstrate both technical competence and a well-implemented quality management system. While most laboratories invest significant effort preparing for accreditation, assessors frequently identify similar nonconformities during initial assessments and surveillance visits.

Understanding these common issues can help laboratories strengthen their quality systems and avoid delays in achieving or maintaining accreditation.

Below are seven of the most frequently observed nonconformities during ISO/IEC 17025 assessments.

1. Incomplete or Poorly Controlled Documentation

Document control is a fundamental requirement of any laboratory quality system. However, many laboratories struggle with maintaining current, controlled versions of procedures and policies.

• Obsolete procedures still in circulation
• Missing revision histories
• Inconsistent formatting or numbering of documents
• Uncontrolled copies of standard operating procedures

A well-structured document control process ensures that personnel are always working from the most current approved procedures.

2. Inadequate Method Validation or Verification

Analytical methods must be demonstrated to be fit for their intended purpose. Assessors frequently identify situations where laboratories have not performed sufficient validation or verification activities.

• Incomplete validation studies
• Lack of documented verification for standard methods
• Insufficient evaluation of accuracy, precision, or detection capability
• Application of methods to new matrices without supporting studies

3. Insufficient Internal Audits

Internal audits are intended to evaluate whether the laboratory’s quality system is functioning effectively.

• Audit programs that do not cover all elements of the quality system
• Lack of objective evidence in audit reports
• Failure to identify meaningful findings
• Infrequent or irregular audit schedules

4. Incomplete Training and Competency Records

Personnel competence is a critical requirement under ISO/IEC 17025.

• Incomplete training documentation
• Lack of competency assessments
• Missing authorization records for specific test methods
• Outdated training matrices

5. Poorly Defined Measurement Uncertainty

Measurement uncertainty is often one of the more technically challenging requirements for laboratories.

• Lack of documented uncertainty calculations
• Failure to include relevant sources of variability
• Uncertainty estimates that are not method-specific
• Missing justification for uncertainty budgets

6. Weak Corrective Action Processes

• Corrective actions that only fix the immediate problem
• Lack of root cause analysis
• No verification of corrective action effectiveness
• Recurring nonconformities

7. Incomplete Management Review Activities

• Missing required inputs
• Lack of documented decisions or action items
• Reviews that do not address quality system performance

Strengthening Your Laboratory Quality System

Many of the nonconformities identified during accreditation assessments are preventable with careful preparation and a well-implemented quality management system.

Regular internal audits, thorough documentation practices, and ongoing staff training can significantly reduce the likelihood of findings.

For laboratories preparing for accreditation or seeking to strengthen their quality systems, understanding common assessment findings is an important first step toward achieving and maintaining compliance with ISO/IEC 17025.

Share this article

Related Resources

• Why Compendial Methods Require Verification — Not Validation — in ISO/IEC 17025 Laboratories
• Proficiency Testing vs Internal Quality Control
• What Happens When a Laboratory Fails Proficiency Testing?

Frequently Asked Questions

What is the most common ISO 17025 nonconformity?
Document control issues and incomplete method validation are among the most common findings during assessments.

How often should laboratories perform internal audits?
ISO/IEC 17025 requires laboratories to conduct internal audits periodically to verify the effectiveness of the quality system.

What happens if a laboratory receives nonconformities?
Laboratories must implement corrective actions and demonstrate that root causes have been addressed.

About Lab Accreditation & Quality Partners

Lab Accreditation & Quality Partners (LabAQP) provides consulting services to help laboratories develop strong quality systems and successfully achieve or maintain ISO/IEC 17025 accreditation.

© 2026 LabAQP. All rights reserved.