Common Assessment Standard for Buyers and Main Contractors

Why Buyers Are Standardising on CAS

Most pre-qualification headaches come from inconsistency: every supplier assessed differently, evidence scattered across spreadsheets and inboxes, and no reliable way to see who's compliant right now. The Common Assessment Standard fixes the consistency problem by giving the whole industry one question set and one set of assessment criteria.

For buyers, that delivers three things:

• Consistency — every supplier measured against the same benchmark.
• Efficiency — suppliers certify once a year through a single Recognised Assessment Body, and the result is shared across providers, so you're not duplicating effort.
• Defensibility — a recognised, auditable basis for who you let onto your projects, which matters more than ever under the Building Safety Act.

It's also increasingly expected of you: public sector buyers are directed to use CAS under PPN 03/24, and many private clients now look for it too. See PPN 03/24 Explained.

Deciding What to Require

Mandating CAS isn't one decision, it's a few:

Core or full CAS? If your projects only need assurance on health and safety, the core (SSIP-level) criteria may suffice. But if you need evidence across environmental, quality, equality, modern slavery and anti-bribery, require a full-CAS tier so suppliers arrive with the right modules already assessed. See CAS vs SSIP, CHAS and Constructionline.

Desktop or site-based? Match the certification level to the risk of the trade and the work.

Building safety. If your projects involve design or building work under the Building Safety Act, require completion of the now-mandatory Building Safety section so you can evidence that your dutyholders have the organisational capability the Act demands. This connects directly to maintaining a reliable Golden Thread of information.

How to Roll CAS Out Across Your Supply Chain

A clean rollout avoids disruption to live projects:

1. Set the policy. Decide the minimum level and modules you'll require, and from when.
2. Communicate early. Tell suppliers what's changing, why, and what they need to do, with a realistic lead time. Many will already hold CAS or SSIP.
3. Run a transition window. Accept existing accreditations alongside CAS during a defined period so you don't stall onboarding.
4. Make it a condition of approval. Once the window closes, CAS becomes a standing requirement for supply chain membership.
5. Monitor continuously. Certification is annual, but insurance and other time-critical documents expire throughout the year, so checking once isn't enough.

For the wider onboarding picture, see How to Reduce Supplier Onboarding Time and How to Score Supplier Risk.

The Real Challenge: Monitoring at Scale

Mandating CAS is the easy part. The hard part is knowing, at any moment, which of your hundreds of suppliers are currently compliant, whose certificates have lapsed, whose insurance expired last week, who never completed the building safety section.

Done manually, this is where supply chains spring leaks: a supplier shows as "approved" on a spreadsheet months after their evidence went stale. That's both a compliance risk and, under building safety obligations, a governance risk.

Mobilize is built for exactly this. It lets buyers:

• Issue CAS-aligned pre-qualification questionnaires and capture responses in one place.
• Validate and store supplier evidence, with automated checks on certificates and insurance.
• Track expiry dates across your whole supply chain and prompt suppliers before documents lapse.
• See live, accurate compliance status for every supplier, not a snapshot that's already out of date.

That turns CAS from a one-off gate into continuous assurance, with far less manual chasing from your team.