Summary
Procurement Policy Note PPN 03/24 is UK Government guidance, issued in March 2024, that directs public sector contracting authorities to use the Common Assessment Standard (CAS) when pre-qualifying suppliers for construction works. For public sector projects above the £5.337 million threshold, CAS is now the preferred pre-qualification method, replacing PAS 91. PPN 03/24 is guidance to buyers rather than a law imposed on contractors - but in practice it means CAS compliance is increasingly a gate to public sector construction work. This guide explains what PPN 03/24 says, who it affects and what suppliers and buyers should do about it.
What Is PPN 03/24?
A Procurement Policy Note (PPN) is official guidance from the UK Government setting out how public sector bodies should approach an aspect of procurement. PPN 03/24, issued in March 2024, addresses the pre-qualification stage of construction procurement.
Its central instruction is straightforward: public sector contracting authorities should use the Common Assessment Standard to pre-qualify suppliers for construction works, rather than the now-withdrawn PAS 91. For projects above £5.337 million, CAS is the preferred method.
Why PPN 03/24 Was Introduced
PPN 03/24 reflects two converging pressures. First, PAS 91 - the long-standing pre-qualification questionnaire - was withdrawn by BSI in April 2023 and is no longer maintained, leaving a gap. Second, the Building Safety Act 2022 raised the bar on the competence and capability that public sector buyers need to verify before awarding work.
The Common Assessment Standard, developed by Build UK, answered both: a modern, regularly updated framework that includes a dedicated Building Safety section. PPN 03/24 simply pointed public procurement at it. For the wider context, see PAS 91 vs the Common Assessment Standard.
What PPN 03/24 Means in Practice
Aspect | Position under PPN 03/24 |
Preferred PQQ | The Common Assessment Standard |
Threshold | Public sector construction projects above £5.337 million |
Status of PAS 91 | Withdrawn; no longer to be used by contracting authorities |
Legal force | Guidance to public sector buyers, not a statutory duty on contractors |
Building safety | CAS includes a Building Safety section aligned to the Building Safety Act |
The important nuance is that PPN 03/24 directs buyers, not suppliers. It does not make CAS a legal requirement for every contractor. But because public sector buyers are directed to use it, suppliers who want public sector work increasingly need to hold it. Adoption is widening rather than universal, so the practical advice is to check the specific pre-qualification requirements of each contract you target.
Who Does PPN 03/24 Affect?
- Central government departments and in-scope public bodies, who are directed to adopt CAS for construction works procurement.
- Suppliers and subcontractors bidding for public sector work, who increasingly need CAS to qualify.
- Framework contractors and their supply chains. Large public and quasi-public programmes - from infrastructure upgrades to airport and estate frameworks - increasingly expect CAS across the supply chain. If you are bidding into a framework, CAS is fast becoming table stakes. (See our look at what Gatwick's £2bn upgrade programme means for supply chains and information management.)
What Suppliers Should Do
- Confirm whether your target contracts require CAS. Check each opportunity rather than assuming PPN 03/24 applies universally.
- Get certified ahead of need. CAS certification takes preparation; leaving it until a tender is live is a common and costly mistake.
- Complete the Building Safety section. It is mandatory under CAS Version 5 if you carry out design or building work under the Building Safety Act.
- Keep evidence current so you stay tender-ready year-round. Our supplier-side PQQ guide covers this in detail.
What Buyers Should Do
Public sector buyers - and the framework contractors who sit between them and the supply chain - need a consistent way to mandate CAS, collect evidence and prove that risk has been managed across the supply chain. Doing that across dozens or hundreds of suppliers by spreadsheet and email does not scale. Our guide on mandating CAS across your supply chain covers the buyer side in full.
How Mobilize Helps
Mobilize lets buyers set pre-qualification requirements such as CAS, automatically collects and tracks supplier compliance evidence, and gives complete visibility of where every supplier stands - so you can evidence PPN 03/24 alignment and building safety compliance without the manual overhead. Suppliers, meanwhile, keep all their documentation in one tender-ready place.
If public sector or framework requirements are pushing you towards CAS, our team can help you get ready.
Posted on 25 May 2026
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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.
Public Procurement Threshold Changes in 2026: What Buyers & Suppliers Need to Know
From 1 January 2026, updated public procurement threshold values will apply across the UK. These changes will affect which contracts fall within the full regulatory scope of the Procurement Act 2023, altering compliance obligations for both contracting authorities and suppliers. While threshold adjustments happen periodically, their practical impact is often underestimated. Changes in threshold values can shift contracts into (or out of) full regulatory coverage affecting advertising requirements, evaluation processes, transparency obligations and audit risk. Understanding what these changes mean and how to prepare is essential for procurement teams and bidders alike.
Common Assessment Standard vs SSIP: What's the Difference?
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.