Validation and verification are constantly used as synonyms but under ISO/IEC 17029 they describe two different jobs, separated mainly by one thing: time. One looks forward at a claim about the future; the other looks back at a claim about what already happened.
As organizations make more public claims greenhouse gas reductions, carbon footprints, sustainability targets, product declarations a quiet question follows every claim: can we trust it? The answer increasingly comes from independent validation and verification bodies working under ISO/IEC 17029, the international standard that governs how such claims are confirmed.
But the two words at the heart of that standard are routinely confused. This article explains the real difference, why it hinges on time, and how it plays out in practice — using greenhouse gas claims as the clearest example.
The short answer
Both validation and verification are ways of independently assessing a claim — a statement an organization makes and wants others to trust. The difference is what the claim is about and when it is assessed.
- Validation assesses a claim about a future or projected outcome the plausibility of something that hasn’t happened yet. It asks: are the assumptions and methods reasonable enough that this projected claim is credible?
- Verification assesses a claim about a past or present outcome something that has already occurred and been recorded. It asks: did this actually happen as stated, based on the evidence?
Put simply: validation looks forward at a prediction; verification looks back at a record.
Why time is the key distinction
The cleanest way to keep these straight is to anchor on the timeline of the claim.
A validation deals with a forward-looking assertion. Because the outcome hasn’t happened yet, it can’t be checked against reality. Instead, the assessment focuses on whether the underlying assumptions, models, and methodology are sound enough that the projected result is plausible. You’re judging the reasoning behind a prediction, not the prediction’s final truth.
A verification deals with a claim about something already done. Here, evidence exists data, records, measurements and the assessment checks the claim against that evidence. You’re judging whether what’s stated matches what actually happened.
This is why the same subject can involve both. A plan can be validated today; the results of executing that plan can be verified later.
A concrete example: greenhouse gas claims
Greenhouse gas (GHG) claims make the distinction tangible, because they involve both directions of time.
Suppose an organization designs a project intended to reduce emissions in the future say, a program projected to cut a certain volume of CO₂ over the next decade. Because those reductions haven’t occurred yet, an independent body validates the project: it examines the baseline assumptions, the calculation methodology, and the monitoring plan to judge whether the projected reductions are credible.
Years later, the organization reports the emissions it actually achieved. Now there’s real data. An independent body verifies that reported GHG inventory: it checks the reported figures against the evidence to confirm they’re accurate and complete.
Same organization, same subject but validation handled the forward-looking projection, and verification handled the historical result. That’s the distinction in action, and it’s exactly the kind of work ISO/IEC 17029 is built to govern.
What ISO/IEC 17029 actually does
ISO/IEC 17029 is the standard for the competence and impartiality of bodies that perform validation and verification, across any sector — GHG, sustainability, financial statements, product claims, and more.
It sits at a general level, setting the common requirements a validation/verification body must meet regardless of the specific field: impartiality, competence, consistent processes, and sound reporting. Sector-specific programs then sit on top of it for particular applications, such as GHG work.
When a validation/verification body is accredited to ISO/IEC 17029, an independent accreditation body has confirmed that it is competent and impartial — which is what lets the market trust the assurance it provides. Without that independent confirmation, a validation or verification statement is only as credible as the body issuing it claims to be.
Quick comparison
| Validation | Verification | |
|---|---|---|
| Claim is about | The future / a projection | The past / a record |
| Core question | Is the projection plausible? | Did it actually happen as stated? |
| Basis of assessment | Assumptions and methodology | Evidence and records |
| GHG example | A projected emissions-reduction project | An actual reported emissions inventory |
Frequently asked questions
What is the difference between validation and verification? Validation assesses a claim about a future or projected outcome and judges whether it’s plausible. Verification assesses a claim about something that has already happened and checks it against the evidence. The key difference is the timeframe of the claim.
What is ISO/IEC 17029? It’s the international standard setting general requirements for the competence and impartiality of bodies that perform validation and verification of claims, across any sector.
Is GHG verification covered by ISO/IEC 17029? Yes. ISO/IEC 17029 provides the general framework, with sector-specific programs applied on top for greenhouse gas validation and verification work.
Why does accreditation matter for validation and verification bodies? Accreditation independently confirms that the body is competent and impartial. It’s what allows regulators, markets, and the public to trust the validation or verification statement rather than taking the body’s word for it.
The bottom line
Validation and verification aren’t interchangeable they do opposite jobs across time. Validation looks forward and asks whether a projected claim is plausible; verification looks back and asks whether a stated result actually happened. ISO/IEC 17029 provides the common framework for the bodies that perform both, and accreditation is what makes their assurance trustworthy.
As claims about emissions, sustainability, and performance carry more weight, the credibility of the body confirming them matters more than ever — and that credibility rests on independent, accredited competence.
The National Accreditation Center (NAC) is a U.S.-based accreditation body operating under ISO/IEC 17011. To learn more about accreditation for validation and verification bodies under ISO/IEC 17029, get in touch with our team.