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The Common Assessment Standard (CAS) Explained: What UK Contractors Need to Know

· Last reviewed: 23 February 2026

If you hold CHAS, Constructionline, or any other SSIP accreditation, you have already been assessed against the Common Assessment Standard. You may not know it by name. Most contractors do not. CAS operates in the background — the framework that standardises what SSIP member schemes actually check.

That quiet background role is changing. Procurement Policy Note 03/24 (PPN 03/24), published by the Cabinet Office, directs public-sector buyers to use CAS-aligned assessment for construction procurement. For contractors who work in or want to work in the public sector, understanding CAS has moved from optional to necessary.

This guide explains what CAS is, how it is structured, which accreditation tiers satisfy it, and what PPN 03/24 means for your business.

What Is the Common Assessment Standard?

CAS is a framework developed under the SSIP (Safety Schemes in Procurement) umbrella. It defines a standardised set of assessment criteria that all SSIP member schemes must use when evaluating contractors.

Before CAS, each scheme set its own criteria. The result was inconsistency — two schemes might both claim to assess health and safety competence, but they were checking different things to different standards. CAS solved this by creating a single set of criteria that every SSIP member scheme assesses against. This is what makes mutual recognition possible: if Scheme A and Scheme B both assess against CAS, then a pass from one should be equivalent to a pass from the other.

CAS is maintained and updated by the SSIP Forum. The current version reflects the latest legislative and regulatory requirements, including provisions related to the Building Safety Act 2022.

For an overview of SSIP and how mutual recognition works in practice, see our guide: What Is SSIP and Which Scheme Should You Choose?.

How CAS Is Structured

CAS is not a single pass/fail assessment. It is structured in modules, divided into core criteria and additional modules.

Core Criteria: Health and Safety

The CAS core criteria cover the health and safety fundamentals that every SSIP assessment must check. These align to UK health and safety legislation — primarily the Health and Safety at Work etc. Act 1974, the Management of Health and Safety at Work Regulations 1999, and the Construction (Design and Management) Regulations 2015 (CDM 2015).

The core criteria include:

  • Health and safety policy — A written policy signed by a senior individual, reviewed within 12 months, with statement of intent, organisation of responsibilities, and practical arrangements.
  • Risk assessment — Evidence of a systematic process for identifying hazards, assessing risks, and implementing controls. Must cover the contractor's specific activities.
  • Training and competence — Records demonstrating workforce competence: CSCS, SMSTS/SSSTS, trade qualifications, ongoing training, and toolbox talks.
  • Monitoring and review — Evidence that health and safety arrangements are monitored, reviewed, and improved. Not just paperwork — active management.
  • Accident and incident reporting — Procedures aligned to RIDDOR 2013 (Reporting of Injuries, Diseases and Dangerous Occurrences Regulations), with evidence of investigation and corrective action.
  • Insurance — Current employers' liability insurance (minimum £5 million as required by the Employers' Liability (Compulsory Insurance) Act 1969) and public liability insurance.
  • Competent advice — Access to competent health and safety assistance as required by Regulation 7 of the Management of Health and Safety at Work Regulations 1999.
  • Subcontractor management — Procedures for vetting and managing subcontractors' health and safety competence.

Every SSIP member scheme — CHAS, Constructionline, SafeContractor, SMAS, Acclaim, Achilles, and the rest — assesses against these core criteria. If you hold any SSIP accreditation, you have met the CAS core.

For a detailed breakdown of what assessors check across all documentation areas, see our guide: Construction Accreditation Requirements.

Additional Modules

Beyond the core health and safety criteria, CAS defines additional assessment modules. These cover compliance areas that are increasingly expected by clients and procurers:

  • Environmental management — Environmental policy, waste management procedures, pollution prevention, and awareness of environmental responsibilities.
  • Quality management — Documented procedures for quality control, inspection, defect management, and continuous improvement.
  • Equal opportunities and diversity — Compliance with the Equality Act 2010, written policy, fair recruitment practices, and grievance procedures.
  • Modern slavery — Due diligence on supply chain labour practices, right-to-work verification, and a proportionate modern slavery statement (aligned to the Modern Slavery Act 2015).
  • Anti-bribery and corruption — Policy and procedures aligned to the Bribery Act 2010.
  • Financial standing — Evidence of financial stability and ability to fulfil contractual obligations.

Not every accreditation tier covers all modules. This is where the distinction between "basic" and "full" CAS compliance matters — and where many contractors get caught out.

Which Accreditation Tiers Satisfy CAS?

This is the question that matters commercially. The answer depends on which modules a particular accreditation tier assesses.

Core CAS Only (Health and Safety)

The following entry-level tiers satisfy the CAS core health and safety criteria:

  • CHAS Standard
  • Constructionline Silver
  • SafeContractor (standard)
  • SMAS Worksafe
  • Acclaim (standard)

These give you SSIP mutual recognition for health and safety. For many contracts, this is sufficient.

Full CAS (Core Plus Additional Modules)

The following higher-tier accreditations satisfy the CAS core criteria plus the additional modules:

  • CHAS Premium Plus — Covers health and safety, environmental, quality, financial, equality, modern slavery, and anti-bribery.
  • Constructionline Gold — Covers health and safety, financial (via Dun & Bradstreet), environmental, quality, equality, and anti-bribery.
  • Achilles BuildingConfidence — Full CAS assessment including all modules, with audit elements for higher risk categories.

The exact mapping between scheme tiers and CAS modules is maintained by SSIP and may be updated. Check the SSIP website or contact your scheme directly for the current mapping.

For a comparison of CHAS, Constructionline, and SafeContractor tiers, see our detailed comparison guide. For more on Constructionline Gold specifically, see our Constructionline Gold guide.

CAS v4 and the Building Safety Act 2022

A recent CAS revision introduced a new section reflecting the Building Safety Act 2022 (BSA 2022). The BSA 2022 established a new regulatory regime for higher-risk buildings in England — residential buildings over 18 metres or 7 storeys, and care homes and hospitals over 18 metres. It created the Building Safety Regulator (part of the HSE) and imposed new duties on dutyholders throughout the building lifecycle.

The CAS v4 Building Safety Act section assesses whether contractors working on higher-risk buildings understand and comply with their BSA duties. For contractors who do not work on higher-risk buildings, this section may not apply. But for those who do — or who want to — it adds a new layer to the accreditation assessment.

If your work involves residential buildings at height, understanding CDM 2015 duties is already foundational. See our guide: CDM 2015 Duties for SME Contractors.

PPN 03/24: Why CAS Now Matters More

Procurement Policy Note 03/24 was published by the Cabinet Office. PPNs are instructions to public-sector buyers on how to conduct procurement. They carry significant weight — while not primary legislation, government departments and other contracting authorities are expected to follow them.

PPN 03/24 directs public sector buyers to use CAS-aligned assessment as part of their construction procurement processes. In practical terms, this means:

Public sector construction contracts should use CAS criteria for prequalification. Buyers are directed to accept accreditation from CAS-aligned assessment bodies (i.e., SSIP member schemes) as evidence that contractors meet the required standard.

The full CAS — not just core — is increasingly expected. For contracts above certain thresholds, buyers may require evidence of compliance with the additional CAS modules (environmental, quality, equality, modern slavery, anti-bribery), not just the core health and safety criteria.

Basic-tier accreditation may not be sufficient. If a public sector buyer follows PPN 03/24 and requires full CAS compliance, holding CHAS Standard or Constructionline Silver alone may not satisfy the requirement. You would need CHAS Premium Plus, Constructionline Gold, or an equivalent full-CAS accreditation.

Important caveats: PPN 03/24 is a direction to public sector buyers, not a statutory requirement imposed on contractors. Adoption is still being rolled out across contracting authorities, and the pace of implementation varies. Not every public sector buyer has updated their procurement processes to reflect it yet. The direction of travel is clear, but the timeline for universal adoption is not. Check the specific prequalification requirements for each contract you are targeting rather than assuming PPN 03/24 applies universally.

The practical effect of PPN 03/24 is that full CAS compliance is increasingly expected for public sector construction work. For contractors who want to be well positioned as adoption widens, acting early is prudent — but it is not yet a universal gate.

For context on how PAS 91 prequalification questionnaires relate to CAS, see our PAS 91 guide.

What This Means for Your Business

If you only work in the private sector and your clients do not require CAS-level accreditation, the immediate impact is limited. Your existing SSIP accreditation — at whatever tier — continues to serve its purpose.

If you work in public sector construction, or plan to, here is what to act on:

1. Check Your Current Accreditation Level

Do you hold core CAS only (CHAS Standard, Constructionline Silver, SafeContractor standard) or full CAS (CHAS Premium Plus, Constructionline Gold, Achilles BuildingConfidence)? If it is core only, you may need to upgrade.

2. Review Your Target Contracts

Look at the prequalification requirements for the public sector contracts you are targeting. Are they referencing CAS? Are they requiring evidence of environmental, quality, equality, and modern slavery compliance? If yes, basic-tier accreditation will not get you through the gate.

3. Prepare for the Additional Modules

If you need to move from core to full CAS, you will need to prepare additional documentation: environmental policy and procedures, quality management procedures, equal opportunities policy, modern slavery statement, and anti-bribery policy.

This is not as onerous as it sounds for most established SMEs. Many already have some of these documents in place — they just have not been assessed against them. The gap is often one of documentation and formalisation rather than fundamental capability.

4. Budget for the Upgrade

Moving from CHAS Standard to Premium Plus or from Constructionline Silver to Gold involves higher fees. Factor this into your annual accreditation budget. For a detailed cost comparison, see our Construction Accreditation Costs guide.

5. Assess Your Readiness

Before committing to an upgrade, benchmark your current position. Use the Construction Accreditation Readiness Scorer to identify gaps in your documentation and management systems.

The Silent Standard

CAS has been shaping construction accreditation for years. Most contractors who hold SSIP accreditation have been assessed against CAS criteria without thinking about it in those terms. The framework worked quietly in the background, ensuring consistency across schemes.

PPN 03/24 has brought CAS into the foreground. For contractors working in public sector construction, CAS compliance is becoming explicit rather than implied. The contractors who already hold full-CAS accreditation — CHAS Premium Plus, Constructionline Gold, or equivalent — are well positioned. Those holding basic-tier accreditation need to understand the gap and plan accordingly.

The standard itself is not new. The requirement to demonstrate compliance with it is.

For the broader context on prequalification in UK construction, see our Complete Guide to Construction Supplier Prequalification.

Disclaimer: This guide is based on publicly available information including published Procurement Policy Notes, legislation, and industry guidance. TenderReady is not affiliated with, endorsed by, or acting on behalf of SSIP, CHAS, Constructionline, the Cabinet Office, the HSE, or any other named body or scheme. Regulatory requirements and accreditation criteria are subject to change — always verify current details with the relevant organisation directly.