The Common Assessment Standard Explained: What Main Contractors and Subcontractors need to know

What is the Common Assessment Standard?

The Common Assessment Standard (CAS) is a unified pre-qualification questionnaire for the construction industry which helps UK construction contractors and subcontractors manage multiple compliance certifications. The Common Assessment Standard is an industry-wide standard, developed by Build UK in collaboration with Constructionline, which provides a comprehensive pre-qualification questionnaire (PQQ) designed to simplify the construction procurement processes and reduce administrative burden.

The Common Assessment Standard question set has transformed how construction subcontractors are able to qualify for projects. As a single standardised assessment, Build UK’s Common Assessment Standard enables main contractors and public sector buyers to thoroughly evaluate construction suppliers and subcontractors through one unified framework, replacing the previous multiple scheme memberships and compliance standards.

This means the Common Assessment Standard has become the industry benchmark for pre-qualification.

The UK Government‘s Procurement Policy Notice 03/24 stated that the Common Assessment Standard was now the preferred method for pre-qualification in public sector procurement projects exceeding £5.337 million.

We’ll explore what getting and maintaining a Common Assessment Standard (CAS) certification means for construction main contractors and subcontractors.

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Common Assessment Standard Certification Benefits

The Common Assessment Standard brings several advantages to both construction main contractors and subcontractors as the industry moves towards a more unified system for prioritising building and fire safety.

1. Improved construction tender opportunities 

Many main contractors and public sector buyers now specify CAS certification on their public sector projects which means, as a subcontractor, if you can demonstrate that your business aligns with the Common Assessment Standard through schemes such as a Constructionline Gold or Platinum membership, you can qualify for a greater number of contracts and find more opportunities.

Subcontractors should also be able to save time and resources: the Common Assessment Standard assessment is reviewed once a year and prevents having to complete multiple Pre-Qualification Questionnaires, thus saving time for both parties entering and reviewing information. You are able to get verified for a Constructionline membership in as little as 3 working days and demonstrate that you meet the Common Assessment Standard. This time can instead be used to find and win new tenders and project opportunities on platforms such as Marketplace Find.

Get in touch with our team to find out how to achieve Common Assessment Standard Certification with Constructionline 

2. Risk management advantages 

The Common Assessment Standard V.4 questions have been divided into 10 sections covering several important areas of construction compliance. These sections are:  

		Identity
		Financial
		Corporate and Professional Standing
		Health and Safety
		Environmental
		Quality
		Building Safety
		Fairness, Inclusion and Respect
		Information Security
		Information Management

Read more about each of these sections in the Common Assessment Standard Question Set in Build UK’s guidance here.

This format makes it easier for subcontractors to complete the PQQ in manageable sections, whilst also providing a reliable framework for main contractors and public sector buyers to feel confident that risks have been reduced and managed across their entire construction supply chain.

3. Competitive differentiation 

Common Assessment Standard (CAS) certification can help smaller to medium sized construction subcontractors qualify for more opportunities, as well as potentially win more bids and public sector contracts.

The two types of audit methods for the Common Assessment Standard are desktop and site-based, which means when you apply for CAS certification from a recognised assessment body such as Constructionline, you can apply for the audit level which is most appropriate for your business based on factors such as trade, size and your requirements.

Also, for businesses with fewer than 10 employees and either an annual turnover or balance sheet total under £1.8 million, the Common Assessment Standard criteria is tailored to align with the size and scale of the business. This ensures fairness while also keeping the assessment standards high.

Enhancing fairness and simplifying the process for smaller to medium subcontractors to achieve CAS certification also benefits main contractors and public sector buyers by expanding their pool of suitable suppliers and subcontractors. This approach aligns with the Procurement Act, coming into effect in February 2025, which is designed to promote transparency throughout the commercial lifecycle, with an increasing emphasis on prioritising tenders that deliver strategic value rather than being solely judged on the lowest price. This will drive more main contractors to work with subcontractors who can demonstrate they align to the Common Assessment Standard.

Find out more about how the Procurement Act could impact you with our resource hubs

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Building Safety Act Integration 

Version 4 of the Common Assessment Standard, published in July 2024, also marks a major step forward in aligning to UK building safety legislation, as it now has a dedicated Building Safety section that aligns with the Building Safety Act.

Alignment with new regulations 

The updated standard will give subcontractors a way to demonstrate their organisational capability in line with BS 8670-1:2024. Suppliers and subcontractors can now confirm their competence by putting the right management policies, procedures, and systems in place and demonstrating this through Common Assessment Standard Certification.

Building Safety Act Golden thread requirements

The Building Safety Act Golden Thread* specifies that digital records must be kept throughout a building’s life cycle. The golden thread requirements state that all building information must be:

• Digital and protected from unauthorised access
• Ready to use when needed in a clear format
• The building’s single source of truth that stays current

*Please note: Golden Thread services are not provided by Constructionline or the Once For All Group. 

Dutyholder responsibilities 

The Common Assessment Standard framework now also references specific Building Safety Act Dutyholders and competency requirements. People who work on building or design projects must show they have the right skills, knowledge, experience, and behaviors. Subcontractors and main contractors must provide evidence of:

• Management policies and procedures that meet the Building Safety Act’s competency rules
• Systems that plan, manage, and track building work
• Resources that meet all relevant rules

See more in the ‘Building Safety’ section of the Common Assessment Standard Question Set Version 4 Guidance.

The alignment of the Common Assessment Standard and the Building Safety Act brings a fundamental change to construction industry certification ensuring that safety measures are now built into every step of the process.

Learn more about Dutyholder regulations in our Secondary Legislation Part 2 whitepaper

 

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Future-Proofing Your Business with the Common Assessment Standard 

The construction compliance landscape is always evolving with the introduction of new legislation such as the Building Safety Act and Procurement Act. This makes it increasingly important for Construction main contractors and subcontractors to ensure they are prepared for future changes. Maintaining a Common Assessment Standard Certification can help with this by ensuring subcontractors can demonstrate how they have adapted to meet these new requirements, with one Pre-Qualification Questionnaire. It also helps make it easier for main contractor when it comes to selecting construction suppliers and subcontractors for their supply chains, where they have the assurance they are aligned with UK construction regulations. 

Preparing for regulatory changes 

At Constructionline, our team is dedicated to keeping both Main Contractors and Subcontractors up to date with the latest regulatory changes in UK construction.

For subcontractors, we provide support in achieving Common Assessment Standard certification, helping you demonstrate compliance with the appropriate legislation applicable to your business.

Get Constructionline Gold to achieve the Common Assessment Standard

For Main Contractors and public sector buyers, our supply chain management tools like Marketplace enable you to publish projects and build out your supply chain from our extensive network of qualified suppliers. 

Speak to our team to find out more about our main contractor and public sector buyer memberships

Summary 

Common Assessment Standard (CAS) certification is vital for construction businesses that want to stay competitive and compliant, and be ready for relevant opportunities.

This unified approach to Construction Pre-Qualification Questionnaires eliminates the need for multiple certifications. It provides complete benefits for tender opportunities, risk management, and supply chain efficiency for both subcontractors and main contractors as well as public sector buyers.

The Common Assessment Standard V.4 now aligns with the Building Safety Act and has adapted these new Building Safety regulations, making it more valuable than ever. Construction companies of all sizes can benefit from its balanced requirements. Being able to demonstrate and choose suppliers who align to the Common Assessment Standard positions both subcontractor and main construction contractor businesses perfectly for greater success and opportunities across both public and private sector projects.