How to verify a contractor's Common Assessment Standard certification

A bidder says it has the Common Assessment Standard (CAS). Before treating that as a passed prequalification check, a buyer needs to know which company is certified, by whom, at what level, and whether the certification is current. The buyer then needs to decide what the certificate cannot answer about the proposed work.

This is a verification workflow for UK construction procurement teams. Suppliers looking for the standard's question set and preparation steps should use our CAS explainer.

1. Ask for the exact assessment record

Request the certificate or assessment record from the bidder, including the issuing body, legal entity, assessment level and dates. Build UK says CAS certification is provided by a Recognised Assessment Body and offers desktop and site-based levels. Check the body's current status on Build UK's list. A supplier being listed on a platform, holding a provider's general membership or displaying an SSIP logo does not by itself establish that it holds CAS certification.

Record the date and source of the check. If the certificate is due to expire before award or work starts, make renewal evidence an explicit award or mobilisation condition rather than allowing the original submission to stand indefinitely.

2. Match the entity and scope to the contract

Compare the certified legal name and company details with the bidding entity and the entity that will actually deliver the work. Group companies, trading names and subcontracting structures can obscure a mismatch. Ask the assessment body or supplier to explain a difference; do not silently treat one entity's certificate as another's.

Then check what the assessment covers. The requested certification level and the supplier's role should fit the procurement instructions. Build UK notes that the appropriate level depends in part on trade, size and client requirements. If the bidder will design, manage or undertake specialist work, determine whether the assessment record and supporting evidence address that role. A CAS certificate is an organisation-level assessment, not a blanket approval for every role, trade or site.

3. Confirm the record with the recognised body

Use the body named on the certificate to verify the current result and any limits, suspension or pending renewal. Build UK provides recognised body information and describes how certified companies can share data between bodies. Data visibility on another portal should be treated as a route to evidence, not as proof that the receiving portal made a fresh assessment.

Where the buyer's process requires a specific body or assessment product, state that requirement clearly and check whether an equivalent CAS assessment from another recognised body is accepted. Avoid unnecessary duplicate questionnaires, but document the decision rather than assuming every platform badge has the same meaning.

4. Separate CAS from SSIP

SSIP schemes mutually recognise health and safety assessments through the Deem to Satisfy mechanism, subject to the scheme's terms and the assessment category. That is useful evidence, but it is narrower than CAS's full question set. A current SSIP certificate does not demonstrate that the supplier has supplied the financial, information security, building safety and other CAS evidence. Conversely, a CAS document should not be described as registration with every SSIP member scheme.

If both are named in the tender, identify which requirement each record satisfies. Keep the procurement response, assessment record and buyer decision together.

5. Complete the work-specific checks

The Health and Safety Executive says a construction contractor needs skills, knowledge, experience and, where an organisation, organisational capability appropriate to the work. A prequalification certificate helps evaluate the organisation; it does not replace planning, risk assessment, supervision or coordination for this project.

Before appointment or start, identify the people and resources proposed for the job, check any licence or statutory registration needed for the activity, review the work-specific hazards and arrangements, and confirm insurance or other contractual conditions. Recheck material changes during delivery. The buyer's decision record should say what CAS established and what was checked separately.

A defensible decision record

The final record should include the certificate checked, its source and date, the legal entity and level, any exception and its owner, the work-specific evidence reviewed, and the person who approved appointment. If something remains unresolved, mark it as a condition with a due date and an explicit decision on whether work may start. Avoid a single undifferentiated “approved” field that hides what has and has not been checked.

For teams comparing contractor prequalification software, ask the vendor to show how it stores the underlying certificate, review decisions and renewal owner for the same supplier. Confirm the workflow in a demonstration; software cannot issue CAS certification or make the buyer's professional judgement for it.

Sources and claim boundaries

• Build UK — Common Assessment Standard: standard owner, certification levels, recognised assessment bodies and data sharing.
• HSE — Are you a contractor?: the competence and organisational capability distinction under CDM 2015.
• HSE — Using contractors: selection and management steps after prequalification.
• SSIP — Deem to Satisfy: limits of health and safety mutual recognition.

Editorial note: Recheck Build UK's current recognised-body list and the certificate's status at publication. The Complys money-page link is a commercial handoff, not evidence of a specific automated verification capability.