Last Updated on December 18, 2025 by Melissa Lazaro

Why ISO/IEC 17043 Is So Often Misunderstood

Here’s what I’ve noticed.
ISO/IEC 17043 usually shows up late in the conversation.

Often during an audit.
Sometimes after a rejected application.

By then, the damage is already done.

Most of the confusion around ISO/IEC 17043 comes from assumptions.
People hear advice meant for labs and apply it to PT providers.
Or they rely on “how it’s always been done.”

Let’s clear the noise.
Below are the most common myths I hear—and what actually holds up in audits.

Myth 1: ISO/IEC 17043 Is Only for Large or Commercial PT Providers

This one comes up a lot.

Small provider?
Niche scheme?
Industry-specific PT?

ISO/IEC 17043 still applies.

The standard doesn’t care about your size.
It cares about what you do.

I’ve worked with PT providers running a single scheme who assumed accreditation was out of reach.
It wasn’t.

Reality:
If you evaluate other laboratories, ISO/IEC 17043 applies—regardless of scale.

Myth 2: ISO/IEC 17043 Is Basically the Same as ISO/IEC 17025

This myth causes the most trouble.

ISO/IEC 17025 is about producing test results.
ISO/IEC 17043 is about evaluating those results.

Different goals.
Different risks.
Different assessments.

I’ve seen organizations try to extend ISO/IEC 17025 to cover PT activities.
Assessors shut that down quickly.

Reality:
ISO/IEC 17025 cannot replace ISO/IEC 17043 if you’re running PT schemes.

Myth 3: Internal Interlaboratory Comparisons Never Require ISO/IEC 17043

Sometimes this is true.
Sometimes it’s not.

If your interlaboratory comparison is:

• Internal only
• Informal
• Used strictly for learning

You’re usually fine.

But once results:

• Are shared externally
• Influence competence decisions
• Are used in accreditation contexts

Things change.

I’ve seen “internal” ILCs quietly turn into external evaluations.
That’s when ISO/IEC 17043 expectations appear.

Reality:
The purpose of the activity matters more than the label.

Myth 4: ISO/IEC 17043 Is Mostly Documentation and Bureaucracy

Let’s be real.
This fear comes from bad experiences with other standards.

ISO/IEC 17043 isn’t about paperwork for the sake of it.
It’s about competence.

Assessors focus on:

• Scheme design
• Statistics
• Impartiality
• Confidentiality

If your statistics don’t make sense, no amount of documentation will save you.

Reality:
The technical thinking matters more than the documents.

Myth 5: ISO/IEC 17043 Accreditation Is Optional If Clients Don’t Ask for It

This one feels logical.
And it’s short-sighted.

Clients don’t always ask—until accreditation bodies do.
And when they do, timelines get tight.

I’ve seen PT providers rush into accreditation under pressure.
That’s expensive and stressful.

Reality:
ISO/IEC 17043 is often expected before it’s explicitly demanded.

FAQs: Quick Answers About ISO/IEC 17043

Is ISO/IEC 17043 mandatory everywhere?
Not always by law, but frequently required by accreditation bodies and industry schemes.

Can a lab hold both ISO/IEC 17025 and ISO/IEC 17043?
Yes. This is common when a lab also operates PT schemes.

How long does ISO/IEC 17043 accreditation take?
Typically several months, depending on scope, readiness, and scheme complexity.

Conclusion: What to Do Instead of Believing the Myths

ISO/IEC 17043 isn’t mysterious.
It’s misunderstood.

Most PT providers who struggle don’t fail technically.
They fail strategically—by believing the wrong advice.

The smarter approach is simple.
Look at what you actually do.
Match it to the right standard.
Prepare before pressure hits.