Common Assessment Standard in Welsh public works procurement

Welsh public works procurement has a specific supplier-selection policy. The Welsh Government's WPPN 001 says Devolved Welsh Authorities (DWAs) should use questions from Build UK's Common Assessment Standard (CAS) for works contracts under the procurement regime that began on 24 February 2025. The questions must still be relevant and proportionate to the particular contract, and equivalent standards must be permissible.

That is a narrower and more useful rule than “every Welsh construction tender requires a CAS certificate”. WPPN 001 speaks to public works selection by DWAs. A private buyer may choose a different process, and a DWA must decide which CAS questions fit its procurement. Suppliers should read the actual invitation before buying an assessment product or assuming that an existing certificate settles every question.

Check whether this is the right procurement route

WPPN 001 covers works contracts, including specified mixed contracts whose works content is subject to the Construction (Design and Management) Regulations 2015, delivered in Wales. It concerns DWAs under the Procurement Act 2023 and Procurement (Wales) Regulations 2024. The note says it applies to procurements commenced under that new regime until superseded or cancelled.

Start by confirming the authority, contract type, location and procurement start date. If a tender began under the earlier Public Contracts Regulations 2015 route, do not treat the new policy as a retrospective rewrite of its issued documents. The Cabinet Office keeps older PPNs in a separate PCR 2015 collection for legacy procurements. If in doubt, ask the authority which rules and selection documents govern this procurement.

What a Welsh buyer should specify

WPPN 001 says the DWA should use questions from CAS at selection or prequalification, but it also instructs each authority to ensure that those questions:

1. are relevant and proportionate to the contract;
2. permit equivalent standards;
3. provide a level playing field for different supplier types; and
4. for public contracts, take account of the covered-procurement objectives in section 12 of the Procurement Act 2023.

The buyer should therefore identify the actual contract risks and capabilities before choosing questions or evidence. A small specialist subcontractor should not be asked to prove the governance of a principal designer if that is not the role it will perform. A certificate is useful evidence where it matches the question, but the authority still needs to state how equivalent evidence will be assessed and how work-specific capability will be checked.

Record the selected questions, rationale, accepted evidence, reviewer, clarification route and decision. Make the same instructions available to all bidders in the procurement. The current WPPN 001 page also points to eTenderWales and Sell2Wales routes for the question set; follow the authority's current tender documents rather than an old downloaded template.

What a supplier should prepare

Read the invitation and mark every requested CAS question against your legal entity, role, trade and evidence owner. If you hold a current assessment from a Build UK recognised body, identify its product and level, not only the provider name. Build UK lists the current recognised bodies and their desktop or site-based products on its CAS page. If the authority accepts equivalent evidence, ask how and where to submit it.

Do not assume all CAS data or documents travel automatically between assessment portals. Build UK's data-sharing route is a separate supplier-consent process for specified verified data. Nor does CAS certification remove the need to answer a project-specific capability question. If your business is very small, the micro-business evidence guide explains question-specific proportionality and N/A routes.

Keep the policy separate from legal duties on the site

CAS is a supplier-selection framework. It does not itself appoint a principal contractor, prepare the construction phase plan, verify named worker competence or discharge an authority's CDM client duties. HSE's commercial-client guidance sets out the distinct project arrangements the client must make. Keep selection evidence and project delivery controls linked, but not confused.

For general CAS background, use our CAS explainer. An organisation evaluating contractor prequalification software can ask a vendor to demonstrate question selection, equivalent-evidence recording and a separate mobilisation gate. This does not assert that Complys currently enforces WPPN 001 or certifies suppliers.

Primary sources and publication gate

• Welsh Government — WPPN 001, updated 8 July 2025: scope, effective regime, CAS selection instructions, proportionality and equivalents.
• Build UK — Common Assessment Standard: current standard, assessment products and recognised bodies.
• Cabinet Office — PPN collection: separation of legacy PCR 2015 policy notes.
• HSE — CDM commercial clients: separate project-specific client duties.

Before publication: Verify the Welsh policy remains current and that the selected live CAS owner does not already answer this Wales-specific public-works task. Recheck Build UK's question set if Version 6 has taken effect.