Summary
The Common Assessment Standard (CAS) and SSIP (Safety Schemes in Procurement) are often confused, but they cover very different ground. SSIP deals only with health and safety competence and provides mutual recognition between H&S assessment schemes. CAS is far broader - a full pre-qualification framework covering 10 areas, of which health and safety is just one. CHAS and Constructionline are not standards at all; they are assessment bodies that can certify you against both SSIP and CAS. This guide explains how they relate, where they overlap, and which your business actually needs.
The Short Answer
SSIP, CAS, CHAS and Constructionline get lumped together because suppliers encounter them in the same place - pre-qualification - but they sit at different levels:
- CAS is a standard: a broad, industry-agreed pre-qualification framework.
- SSIP is a standard, but narrow: it covers health and safety competence only.
- CHAS and Constructionline are assessment bodies: organisations that assess you against standards like SSIP and CAS and issue the certification.
Get that distinction clear and the rest falls into place. If you want the full background on the broad framework first, read what the Common Assessment Standard is.
Common Assessment Standard vs SSIP
The key difference is scope. SSIP exists to stop suppliers proving their health and safety competence over and over to different schemes - it provides "deemed-to-satisfy" mutual recognition across member H&S schemes. It does not assess your finances, environmental management, quality, building safety or information management.
CAS does all of that. Health and safety is one of its 10 sections; the others cover identity, financial standing, business and professional standing, building safety, environmental management, quality, equal opportunities, business ethics and information management.
The two interact rather than compete: holding a valid SSIP certificate can satisfy much of the CAS Health & Safety section, saving you duplicating that work.
Common Assessment Standard (CAS) | SSIP | |
Type | Broad pre-qualification standard | Health & safety standard (narrow) |
Scope | 10 risk areas incl. finance, environment, quality, building safety | Health & safety competence only |
Who runs it | Build UK | SSIP (umbrella for member H&S schemes) |
Building safety | Dedicated mandatory section (V5) | Not covered |
Public sector procurement | Preferred PQQ under PPN 03/24 | Recognised for H&S element |
Relationship | A valid SSIP certificate can cover the CAS H&S section | Can feed into CAS |
Where CHAS and Constructionline Fit
CHAS and Constructionline are Recognised Assessment Bodies - organisations Build UK has authorised to certify suppliers against CAS. They can also assess you for SSIP. So you don't choose "CHAS or CAS"; you choose CHAS (or Constructionline, or another body) as the route to CAS.
- Constructionline is the founding CAS assessment body, and most suppliers achieve CAS through its Gold membership (Platinum adds a site audit). Around 80% of UK suppliers certify through Constructionline.
- CHAS is a founding SSIP member and a Recognised Assessment Body for CAS, offering CAS through its higher membership tiers.
Because of the CAS data-sharing agreement, whichever body you use, your certification can be shared with the others and with clients - you only certify once.
Which One Does Your Business Need?
- If you only need to prove health and safety competence - and your clients only ask for that - SSIP (via a body like CHAS) may be enough.
- If you bid for public sector work above £5.337 million, or for main contractors who mandate it, you need CAS - see PPN 03/24 explained.
- If you do design or building work under the Building Safety Act, you need CAS with the now-mandatory Building Safety section.
In short: SSIP is a component; CAS is the comprehensive standard most buyers now expect. For many suppliers the practical route is to obtain CAS through a Recognised Assessment Body, using existing SSIP and ISO certificates to shortcut the relevant sections.
Stop Duplicating Compliance Work
The whole point of CAS - and of SSIP recognition feeding into it - is to assess once and reuse. The same logic applies to managing the evidence behind it. Mobilize keeps your accreditations, certificates and policies in one place and tracks expiries automatically.
Not sure which route is right for your business? Talk to our team.
Posted on 25 May 2026
Related platformMobilize
Supply Chain Management
Mobilize offers a fully customisable suite of tools designed to help you manage your entire supply chain with precision giving you complete visibility and control so that you can reduced risk at every stage, from onboarding through to project review.
Find out more
The Common Assessment Standard Checklist: All 10 Sections Explained
The Common Assessment Standard (CAS) question set is divided into 10 sections, each covering a different area of compliance and risk management. To pass your audit, you need the right evidence ready for each one - not just a yes/no answer. This checklist explains all 10 CAS sections, what each looks for, and the documents you should have to hand before you start. Use it to gap-check your own readiness, then download our free CAS checklist to track your progress section by section.
What Is the Common Assessment Standard (CAS)? A Complete Guide
The Common Assessment Standard (CAS) is the UK construction industry's standardised pre-qualification questionnaire (PQQ), developed by Build UK. It replaced PAS 91 - which was withdrawn by BSI in April 2023 and is now the preferred pre-qualification method for public sector construction procurement under Procurement Policy Note PPN 03/24. CAS uses a single industry-agreed question set, divided into 10 sections, that lets a supplier prove their capability and compliance once and share it with multiple buyers. The current Version 5 (published 1 July 2025) made the Building Safety section mandatory. Around 21,000 suppliers now hold CAS certification through one of seven Recognised Assessment Bodies.
How to Get Common Assessment Standard Certified: A Step-by-Step Guide for Suppliers
To get Common Assessment Standard (CAS) certified, you apply to one of the seven Build UK Recognised Assessment Bodies - such as Constructionline, CHAS or Compliance Chain - complete the industry-agreed question set, submit supporting evidence and pass either a desktop or site-based audit. Certification lasts one year. Because of CAS data sharing, you only need to be certified once and can then share the result with other bodies and clients. This guide walks through the process step by step, explains the two audit levels, and shows how to prepare so you pass first time.