The Common Assessment Standard, Explained: Who Needs It and Who Certifies It

So a main contractor or a council has just asked you for "CAS" or "the Build UK standard" — what is it, and what do you actually have to do? The Common Assessment Standard is a single industry-agreed pre-qualification question set that you get audited against once a year by one of seven Recognised Assessment Bodies. It is not another safety badge to bolt on next to your SSIP certificate, and it is not something your existing SSIP certificate will get you into for free. It sits above SSIP, and it is one of the tiers SSIP mutual recognition does not open for you — a valid SSIP certificate can exempt you from parts of the assessment, but it will not, on its own, produce a Common Assessment Standard certificate.

The short version (TL;DR)

The Common Assessment Standard, developed by Build UK, is the industry-agreed pre-qualification question set that replaced PAS 91 as the default PQQ for UK construction. You obtain it from one Recognised Assessment Body of your choice — Achilles, Compliance Chain, Constructionline, CQMS, SCCS, Smas Worksafe or Veriforce CHAS — at either desktop or site-based level, and the certificate lasts one year from the date of issue. Build UK does not set the price: each Recognised Assessment Body has its own fee structure, and in practice you buy it as that body's upper membership tier (Constructionline Gold, CHAS Elite, Worksafe Pro and so on), usually priced by turnover band. Over 21,000 supply chain companies were certified to it as at Build UK's July 2025 FAQs. The single most expensive mistake small firms make is holding it twice, from two different bodies, because two different main contractors named two different portals.

What is the Common Assessment Standard?

The Common Assessment Standard is a question set plus corresponding assessment standards, owned and maintained by Build UK, used to pre-qualify construction suppliers. According to Build UK, there are two levels of certification — desktop and site-based — and you apply to a Recognised Assessment Body for whichever level suits your trade, size and clients. You do not need both.

Version 5 of the question set was published on 1 July 2025 and made the Building Safety section mandatory for every company that falls within its scope, per Build UK's FAQs. Build UK's infographic puts the standard at 176 questions covering 10 key areas of organisational capability. Build UK has confirmed that Version 6 will be published on 1 November 2026, so if your renewal falls late in 2026 expect the question set to move under you.

Who actually needs the Common Assessment Standard?

There are three realistic triggers for a small subcontractor, and none of them is "it's a good idea":

1. A main contractor specifies it. Build UK publishes the list of organisations using it for their supply chains — over 30 contractors, clients and trade associations as at 04/08/2026, including Balfour Beatty, Kier, Mace, Skanska, Wates, Galliford Try, HS2 and SCAPE. If your best-paying client is on that list, the ask is coming.
2. You want public sector work. Build UK states that central government departments and wider public sector bodies should use the Common Assessment Standard to pre-qualify suppliers for construction works contracts, in line with PPN 03/24 and the procurement specific questionnaire. Procurement rules only bite above the relevant contract thresholds and those thresholds are revised periodically — as of 04/08/2026, confirm the current position with the buyer rather than assuming.
3. Your trade association audit accepts it. Build UK notes that a number of its trade association members now accept the Common Assessment Standard as part of their own membership audit, which removes a duplicate assessment if you're already a member.

If none of those apply — you're doing domestic work, private clients and small commercial jobs where an SSIP certificate satisfies everyone — the Common Assessment Standard is a cost you don't need yet. Nobody in the industry gives you extra marks for over-certifying.

Is the Common Assessment Standard the same as SSIP?

No, and this is where most of the confusion (and most of the wasted money) lives. SSIP member schemes assess health and safety competence, and SSIP mutual recognition — "Deem to Satisfy" — means one SSIP certificate should be accepted in place of another. The Common Assessment Standard is far wider than health and safety, so mutual recognition does not carry you into it. In practice, that means: holding an SSIP certificate from any mutually-recognised scheme will not stop a Build UK contractor asking you for CAS separately, and it will not stop you paying for it separately. It can shorten the audit — an existing SSIP certificate typically exempts you from the health and safety sections of the CAS question set — but it does not substitute for it. That's the honest limit of SSIP, which we cover in detail in what SSIP mutual recognition does not cover.

The useful mechanical detail: holding a valid SSIP certificate can exempt you from parts of the assessment. Constructionline, for example, lists exemptions from sections where you already hold industry-recognised accreditations such as SSIP certification, and states that SSIP is now included across its Bronze, Silver, Gold and Platinum memberships. So your SSIP work isn't wasted — it just doesn't get you the certificate.

Which schemes give you the Common Assessment Standard?

This is the bit the individual scheme websites won't tell you plainly, because each one only sells its own product. Build UK lists seven Recognised Assessment Bodies and the exact product name that constitutes the Common Assessment Standard at each. Note the two "not applicable" cells — if a client insists on a site-based audit, two of the seven cannot do it at all.

Source: Build UK, Recognised Assessment Bodies table, checked 04/08/2026. For the full 176-question breakdown by section, see our Common Assessment Standard question set guide, which sits alongside this pillar page under SSIP accreditation.

Because of the Build UK data sharing agreement, verified answers to 33 key questions are shared between Recognised Assessment Bodies in real time, so a buyer can pull your pre-qualification data from any of them regardless of who audited you. No original documents are shared — only the verified data. That is why holding the standard twice buys you almost nothing.

What does the Common Assessment Standard cost?

Build UK is explicit that it does not set the price: each Recognised Assessment Body has its own fee structure, and you get the figure directly from them. In practice the cost is the price of that body's upper membership tier, and those tiers are usually banded by annual turnover. Constructionline, for instance, states that suppliers pay an annual fee based on turnover, with a one-off joining fee for new members based on the turnover band, and that only the annual fee applies from year two onwards.

So the cost question resolves into three numbers, not one:

• The tier price for the CAS-level product (Gold, Elite, Worksafe Pro, Premium, etc.), by turnover band.
• A first-year joining fee, where the body charges one.
• What you're already paying for a standalone SSIP certificate that may now be bundled into that tier — which is where the genuine saving hides.

For what CAS certification actually costs a subcontractor, see Common Assessment Standard cost. For the current published figures on the two routes small firms most often compare, see our CHAS accreditation cost breakdown and Constructionline cost guide, and the tier-by-tier detail in Constructionline Gold vs Silver vs Bronze.

A worked example: the 12-engineer M&E firm

Say Mick runs a 12-engineer mechanical and electrical firm. He already holds an SSIP certificate through one scheme, renewed every year, and it has been enough for six years. Then two things land in the same month: a Build UK main contractor asks for the Common Assessment Standard including the Building Safety section, and a council framework worth around £5k a year of recurring maintenance references CAS in its pre-qualification pack.

The wrong move — and the common one — is to answer each request in the portal it arrived in: buy the CAS tier from the contractor's named scheme, and buy it again from the portal the council's consultant mentioned. Two audits, two annual fees, two renewal dates, and the same insurance certificates uploaded twice.

The cheaper route is to work backwards from the requirement. Ask both buyers whether they will accept CAS from any Recognised Assessment Body, since Build UK's whole premise is that they should. Establish whether either needs site-based rather than desktop — because if they do, Smas Worksafe and Compliance Chain can't provide it and the choice narrows to five bodies. Then upgrade with a single body, ideally the one already holding your SSIP data so the health and safety sections carry over, and file a data sharing request so the other portals show your verified answers.

1. 1
   Get the requirement in writing. Ask the buyer for the exact wording: Common Assessment Standard desktop or site-based, and whether any Recognised Assessment Body is accepted. This one email decides everything else.
2. 2
   Audit what you already hold. List every scheme you pay for, the tier, the renewal date and the annual fee. If two of them are CAS-level products, one is redundant.
3. 3
   Pick one body and one level. Choose on price for your turnover band, whether it offers the level your client needs, and whether your existing SSIP data sits there already.
4. 4
   Prepare the evidence before you open the portal. The question set is published — read it first. Our Common Assessment Standard question set guide walks the 10 sections and what each one wants to see.
5. 5
   Request data sharing, then diary the renewal. Your certificate runs 12 months from the date of issue, and time-critical documents expire on their own schedule. Put insurance and certificate dates in the same calendar — see tracking accreditation renewal deadlines.

Is the Common Assessment Standard realistic for a one-van or micro business?

Yes, with a caveat. Build UK states that for companies meeting the criteria for a micro-business, the assessment standards are applied in a proportionate way, and its FAQs confirm the standards for certain questions have been revised for use with micro-entities. The question set itself allows for smaller firms — for example, where a company has fewer than five employees and no written arrangements, it can describe how it manages the risk instead.

That proportionality applies to the standard you're judged against, not to the price band or the number of questions you see. A sole trader still walks through corporate standing, insurance, environmental and building safety questions. Whether that's worth it depends entirely on whether a real, named contract is behind the request — which is the same test we apply in do I need more than one accreditation scheme?

Frequently Asked Questions

What is the Common Assessment Standard?

The Common Assessment Standard is an industry-agreed pre-qualification question set, owned and maintained by Build UK, that assesses construction suppliers across 10 areas including health and safety, environmental management, quality, financial standing and building safety. You get certified against it by one of seven Recognised Assessment Bodies, at either desktop or site-based level, and the certificate lasts one year from the date of issue.

How much does the Common Assessment Standard cost?

Build UK does not set a price — each Recognised Assessment Body has its own fee structure, and the cost is effectively the price of that body's upper membership tier (for example Constructionline Gold or Platinum, or CHAS Elite), usually banded by annual turnover, plus a one-off joining fee in year one for some bodies. See our CHAS accreditation cost breakdown and Constructionline cost guide for the current published figures.

Is the Common Assessment Standard the same as SSIP?

No. SSIP member schemes assess health and safety competence, while the Common Assessment Standard covers 10 areas including environmental, quality, financial and building safety alongside health and safety. Holding an SSIP certificate can exempt you from parts of the assessment, but it does not give you the Common Assessment Standard.

Do I need the Common Assessment Standard from more than one assessment body?

Generally no. Build UK's data sharing agreement means verified answers to 33 key questions are shared between Recognised Assessment Bodies in real time, so buyers can find your data through any of them. Build UK itself advises companies to check whether they are certified more than once and whether there is any reason for it.

How long does Common Assessment Standard certification last?

Build UK confirms the certificate is valid for one year from the date of issue, provided time-critical documents such as insurances are updated when they expire. Miss one of those expiry dates and your shared data can show as lapsed before the annual renewal comes round.

Should I choose the desktop or the site-based assessment?

Build UK states companies choose one level, not both, based on trade, size and what their main contractors or clients require. Ask the buyer directly — and note that of the seven Recognised Assessment Bodies, Compliance Chain and Smas Worksafe are listed as desktop only, so a site-based requirement narrows your choice.

Did the Common Assessment Standard replace PAS 91?

Effectively, yes. Constructionline notes that PAS 91 has been withdrawn by the British Standards Institution, and Build UK states that central government and wider public sector bodies should now use the Common Assessment Standard to pre-qualify suppliers for construction works contracts under PPN 03/24 and the procurement specific questionnaire.

Last reviewed: 04/08/2026. Figures and scheme product names checked against Build UK's Common Assessment Standard page and Build UK's FAQs on that date. Fees are set by each Recognised Assessment Body and change without notice — confirm the current price and question set version directly with the body before you buy. This guide is information, not compliance advice; for anything specific to your business, ask the scheme or a qualified professional. Start with the wider picture in our SSIP accreditation guide.