Ari Fatah, Technical Standards Manager, Veriforce CHAS
As construction standards evolve, housebuilders and developers face increasing pressure to demonstrate the compliance and competence of their contractors and wider supply chains.
Prequalification certifications and processes are essential components of risk management, and ensuring a safe and qualified supply chain, but with PAS 91 withdrawn, SSIP being widely requested and the Common Assessment Standard (CAS) being the current recommended benchmark, it can be unclear which certifications are required and when.
Selecting the right level of assessment is crucial for compliance, while helping contractors avoid duplicated efforts, strengthening supply chain credibility, and reducing the risks to health and safety, and building safety.
So, what are the key differences between PAS 91, SSIP, and CAS?
The transition from PAS 91 to CAS
Once a universal framework for assessing contractor capability, PAS 91 originally served as a standardised prequalification assessing capability across five core areas of risk management. This included health and safety, environmental impact and sustainability, quality management, financial and business standing, and diversity, equality and inclusion (DEI). In terms of key benefits, its standardisation stood out – PAS 91 enabled contractors to complete a single structured questionnaire rather than responding to several bespoke pre-qualification questionnaires (PQQs) for different clients.
However, in April 2023, PAS 91 was formally withdrawn by the British Standards Institution (BSI) and is no longer maintained or recommended by the government. While some prequalification processes may still reference elements of the legacy framework, all organisations are strongly encouraged to transition to CAS to align with current industry expectations.
Known as the most comprehensive construction prequalification assessment currently available, CAS builds on the structure of PAS 91, while expanding its scope to reflect evolving regulatory and compliance requirements, including those introduced by the Building Safety Act 2022. Developed by Build UK, in collaboration with the Civil Engineering Association (CECA) and industry experts, CAS covers 13 key areas of risk management – from core elements such as health & safety, building safety, quality and environment, to identity, information security, information management, anti-bribery and corruption.
CAS is now the prequalification standard for central government construction procurement. Following implementation deadlines introduced during 2024, CAS certification is also growing within the private sector, particularly among property developers seeking a comprehensive, standardised approach to supply chain risk management.
The role of SSIP in demonstrating compliance with health and safety standards
Alongside CAS, SSIP (the Safety Standards in Procurement) plays an important role within the construction prequalification landscape in assessing contractors against core health and safety criteria aligned with guidance from the Health and Safety Executive (HSE).
However, it’s important to note that unlike the now withdrawn PAS 91, or CAS, SSIP is not an assessment. It’s an umbrella forum that coordinates multiple health and safety assessment schemes under a recognition framework, allowing contactors to demonstrate competence without duplicating assessments, with all SSIP schemes recognising each other’s certifications, through the ‘deem to satisfy’ process.
The importance of demonstrating compliance at multiple levels
SSIP is often used as a baseline by many construction firms and developers to demonstrate health and safety competence, particularly for subcontractor approval and supply chain compliance.
In practice, it’s important to demonstrate compliance throughout the supply chain at multiple levels – for example SSIP certification demonstrates that the baseline standard for health and safety has been achieved, while broader organisational assurance can be demonstrated through CAS, to support organisational assurance and compliance with the requirements set out under the Building Safety Act 2022 and Health & Safety at Work Act 1974. For instance, a developer may mandate SSIP for subcontractors on their sites, while mandating CAS for key duty holders, such as the Principal Contractor and Principal Designer.
Combined, these assessments provide greater visibility across the supply chain, supporting more informed procurement decisions and reducing risk. For organisations seeking a more consistent approach to contractor assessment, compliance experts such as CHAS help ensure contractors meet required prequalification standards, reducing procurement complexity and minimising the risk of penalties and reputational damage associated with non-compliance.
SSIP and CAS are critical components of a safe and secure supply chain in the construction industry. As procurement standards continue to evolve, understanding the differences between the assessment levels will be crucial to maintaining contractor compliance and raising risk management standards across the construction industry.
For more information visit: CHAS: The UK Leader in Compliance & Risk Management