The ISO 17025 internal audit is often overlooked by laboratories whether they are accredited or not. Too often, labs treat the internal audit as paperwork for the assessment company instead of a real opportunity for continuous improvement. Many companies are missing out on a major opportunity to improve their business. A well-designed internal audit system will decrease the amount of time spent each year responding to your external assessor audits. A well-designed internal audit system can greatly improve business performance and help management determine which key operational metrics are necessary or need improvement. Before we can talk about how to improve the internal audit systems we have in place, we should first talk about what components make up the internal audit system.

What are the Components of the ISO 17025 Internal Audit system?

1. Internal Audit Schedule
2. Internal Audit Checklist
3. Internal Audit Report
4. Audit Related Documents

Design a Strategic Internal Audit Schedule

So, the first part of the internal system is the audit schedule. This is a simple but often overlooked step in ISO implementations. Many companies don’t set up their internal audit schedule in a way that drives continuous improvement and long-term success. For example, many labs schedule an internal audit once a year. This forces the internal auditor to cover the entire ISO 17025 checklist in a single sitting. This isn’t technically wrong from an ISO compliance standpoint. In fact, you can pass an audit with a schedule like this. However, there are far better ways to approach internal audits for compliance and collecting valuable insights.

When labs cram their entire internal audit into one yearly session, the quality of investigation questions drops fast. Auditors usually start strong, offering sharp insights early on, but fatigue and time pressure kick in. As the audit drags on, they rush through sections and document findings less thoroughly, weakening the overall result. This will happen to all Internal Auditors including the highly motivated and knowledgeable ones. They will have less time to investigate and spend more time worrying about just finishing the report.

Tips for Better 17025 Internal Audit Schedules

There is nothing in the ISO 17025 standard that states you have to perform the internal audit all at once! So, what are some better strategies for creating internal audit schedules that reduce auditor fatigue? One way is to break up the internal audit into multiple more frequent audits throughout the year. A good way to accomplish this is to separate the audit by the ISO 17025 standard sections. For example, questions relating to ISO 17025 section 4 would be part of a single audit. And items relating to ISO 17025 section 5 would be a separate internal audit. Here is an example of an internal audit program that audits the ISO 17025 sections separately:

In the example above, the number of internal audits has increased. This may seem like more work at first, however each audit will have significantly less questions. This helps auditors focus on a quality over quantity approach when performing audits and filling out reports. Since there is less chance of auditor fatigue, it’s more likely that all the audit questions will receive the same amount of attention. So, creating a schedule that contains audits more often, but has a reduced number of questions is a great first step to producing more valuable and insightful internal audit reports.

Another way to reduce internal auditor fatigue is to pick appropriate audit questions and ensure that the questions are not too repetitive. The questions on the internal audit checklist will determine how valuable the information on the audit report will be. In the next section, we’ll look at the audit checklist.

17025 Internal Audit Checklist – Quality over Quantity

The audit checklist is such a pain to create, but it’s one of the most important pieces of the internal audit system. The audit checklist is the tool your auditors use to find problems and document them as non-conformances. Design your audit checklist to help auditors uncover problems, inefficiencies, and nonconformities as they move through their questions. So, how should the lab go about creating the internal audit checklist? Well, it depends. There is a good method for creating the checklist for labs seeking ISO 17025 accreditation for the first time. Accredited labs should modify the checklist used for the initial accreditation. More on this below.

Creating an Internal Audit Checklist – Labs seeking 1st time Accreditation

Labs seeking accreditation must complete a pre-audit checklist provided by their assessment body. Here is an example of what PJLA requires of their first time customers. This checklist (called the LF-56 Checklist) is a comprehensive list of questions that covers the entire ISO 17025 standard and all the requirements the accreditation body requires (in this case, PJLA). So, if you click that link, you will find out that that document is pretty extensive. It’s best to use this document as the internal audit checklist for the first (and maybe the second) year of accreditation. It would be redundant to create another internal audit checklist separate from this document. It makes sense to just fill out the LF-56 checklist and generate your first audit report from the results. While this may work in the early stages, it’s not an effective long-term strategy.

Here is a picture of a part of the LF-56 checklist just in case you didn’t want to click on the link.

Creating an Internal Audit Checklist – Labs that are already Accredited

If your lab is preparing for its first accreditation, using the full LF-56 or similar style checklist from the accreditation company makes sense. You’ll need to make sure every clause is covered before your assessment. However, once your lab achieves accreditation, the internal audit checklist should evolve into something more specific and useful.

A good internal audit checklist focuses on both compliance and business performance. You want questions that not only confirm your lab meets the ISO requirements but also uncover opportunities for process improvement. For example, instead of simply asking the question from 6.4.13 on LF-56 “Are equipment records maintained?” a better question might be, “How often are equipment records reviewed for accuracy, and what process ensures timely updates?” The second version prompts analysis and improvement rather than a yes-or-no answer. There are more examples of improvements to audit questions in the table below.

Example Internal Audit Question Improvements

LF-56 Standard Question	Improved Question
Does the laboratory have a procedure for handling, transport, storage, use and planned maintenance of equipment in order to ensure proper functioning and to prevent contamination or deterioration? – ISO 17025 6.4.3	Ask a technician to perform the receiving, transport, storage, and planned maintenance procedure for a handheld multimeter (or pick another type of equipment) according to the Equipment Handling Procedure SOP-013. Did the procedure accurately depict what the technician performed? Does the procedure need to be updated?
When intermediate checks are necessary to maintain confidence in the performance of the equipment, are these checks shall be carried out according to a procedure? – ISO 17025 6.4.10	Ask a technician to show when the last intermediate check was performed for a random reference standard that is currently in use. Was the recorded result of the intermediate check documented in accordance with the Intermediate Checks Procedure SOP-014? Are the intermediate checks being performed on the schedule or at intervals defined in SOP-014?
Does the laboratory have a procedure for the review of requests, tenders and contracts? – ISO 17025 7.1.1	Get the most current copy of Review of Requests SOP-015. Find a Work Order from the past 6 months (FORM-011). Does the work order have the requirements for calibration noted? Did the customer agree to the specifications, tolerances, and decision rules on the Work Order?

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More about the Improved Internal Audit Questions

Notice the improved questions are asking technicians to perform activities and the auditor is actually comparing them against the written procedure. This approach helps you keep your SOPs up to date and ensures new employees receive training on the latest documents. In the last example in the table, the audit question is asking about Work Orders. There are many cases where work has to be re-done if the customer didn’t agree to the specifications, decision rule, and other details outlined in the Work Order. This is a huge time and resource burden. Including a question like this in the internal audit helps auditors see if Work Orders are completed properly.

You can get some ideas of what to ask regarding equipment by visiting our ISO 17025 and ISO 9001 Equipment Requirements Blog.

Internal Audit Reports – Turning Findings into Improvements

Once the audit is complete, the next key piece is the Internal Audit Report. This document should do more than summarize what was found. A strong report connects findings to real actions. It should clearly outline what was reviewed, what nonconformities were identified, and what corrective actions are needed.

The key to success with the Internal Audit Report is to assign action items to individuals. For example, if an audit report shows an NCR for 7.1.1 (from the table above), the review and escalation of this finding should be assigned to a specific employee. This is the best way to create accountability for addressing audit findings. One way of accomplishing this is to create an NCR/CAR Tracking Form and ensure that populating new NCRs and CARs on the Tracking Form from internal audits is an assigned responsibility. This form is designed to keep a record of all NCRs and CARs and where they originated from.

Example of NCR/CAR Tracking Form

Other Related Audit Documents – Think Continuous Improvement

The final component of a strong internal audit system is what happens after the report. The post-audit documents — corrective action forms, follow-up records, and management review notes — are where the real improvement cycle happens. These documents should show that findings were addressed, actions were taken, and results were verified.

A management review of these documents is essential. This is the point where leadership evaluates whether the internal audit program is actually driving improvement or just producing paperwork. Reviewing trends over time helps management identify recurring issues, measure the effectiveness of corrective actions, and adjust goals for the next cycle.

When the internal audit program connects these steps — schedule, checklist, report, and follow-up — it transforms from a compliance task into a continuous improvement engine. It helps leadership stay informed, auditors stay focused, and the organization stays ahead of its assessors.

Final Thoughts

A strong internal audit system is more than an ISO requirement — it’s a strategic advantage. By breaking audits into manageable pieces, using smarter checklists, and closing the loop with effective reporting and follow-up, labs can save time, reduce stress, and make measurable improvements each year.

Internal audits don’t have to feel like busywork. When built with purpose, they become the foundation of a lab that doesn’t just stay compliant — it keeps getting better.