What is the difference between validation and verification?
Validation assesses a project's design: whether the proposed activity, baseline, methodology and monitoring plan meet the rules, before the project is registered. Verification assesses a project's performance: whether the emission reductions or removals it reports actually occurred, after monitoring has taken place.
Put simply, validation asks whether the plan is sound and verification asks whether the plan was followed and worked. They are frequently confused, and the confusion matters commercially: a validated project has permission to proceed, not credits to sell. Credits arrive only after verification.
What is the full sequence?
Every VCS project follows the same path, whatever its type. The stages below are sequential, and each produces a document that the next stage depends on.
| Stage | What happens | Who |
|---|---|---|
| Design | The project selects a methodology and writes a Project Description covering baseline, boundary and monitoring plan | Project proponent |
| Validation | Independent assessment that the design meets VCS rules and the chosen methodology | Accredited VVB |
| Registration | The project is entered on the Verra Registry and can begin crediting | Verra |
| Monitoring | The project measures according to its plan and writes a Monitoring Report | Project proponent |
| Verification | Independent assessment that the reported reductions or removals actually occurred | Accredited VVB |
| Issuance | Verified Carbon Units are issued to the project, less the buffer contribution | Verra |
| Retirement | A unit is permanently withdrawn on behalf of a buyer making the claim | Registry account holder |
Monitoring, verification and issuance then repeat for each subsequent period across the crediting period, which for a forestry project runs for decades. That repetition is the part that most affects operating cost, and the part a project designs for least often.
Why does the VVB sit outside both Verra and the project?
The body that writes the rules should not be the body that certifies compliance with them, and neither should the party being certified. An accredited validation and verification body is independent of both, which is what allows a buyer to treat the resulting unit as evidence rather than as a claim.
It also sets the standard of evidence a project has to meet. A VVB is attesting to something it will be held accountable for, so it asks for records that can be traced to specific measurements at specific places on specific dates. Evidence assembled retrospectively to satisfy an auditor tends to look exactly like what it is.
What does this mean for how a project is set up?
The monitoring plan written at design stage is a commitment. It says what will be measured, how often, to what precision, and it is what verification will be conducted against years later. A plan that is easy to write and hard to execute creates a recurring problem at every verification cycle.
This is the argument for designing the measurement system alongside the Project Description rather than after it. See the VCS document library for the Project Description and Monitoring Report templates — reading them early is the cheapest way to find out what will be asked for — and digital MRV for what continuous evidence capture involves.