Constructionline, CHAS or PAS 91: Which Pre-Qualification Does a Subcontractor Need?

If you run a civils or groundworks business, you will know the routine. A new main contractor wants you on its supply chain, and the first thing that arrives is a pre-qualification questionnaire. Company details, insurances, health and safety policy, accident record, environmental policy, quality procedures, equality, modern slavery, financial accounts. You answered the same questions for the last buyer, and for the one before that.

Then the scheme names start. One buyer wants Constructionline Gold. Another wants CHAS. A council tender mentions PAS 91, and a utility client asks whether you are SSIP accredited. It is easy to end up paying for three memberships that check the same paperwork.

This guide explains what each name actually means, which buyers tend to ask for which, what is officially required and what is simply requested, and how a small civils firm can decide. Prices are taken from the scheme owners' own pages at the time of writing (October 2026). We do not recommend one scheme over another; the right one is whichever your customers accept.

Why pre-qualification keeps repeating itself

Pre-qualification is the stage before a tender or a supply chain place where a buyer checks that you are a legitimate, insured, safe and competent business. It happens before anyone looks at your price. For a subcontractor, failing it means you never get the chance to quote.

The duplication came from every buyer writing its own questionnaire. The industry has tried to fix that three times, and each attempt left a name behind: PAS 91, SSIP and the Common Assessment Standard. The commercial schemes, Constructionline and CHAS among them, are the organisations that assess you against those standards and hold your data so buyers can check it.

PAS 91: the standard questionnaire that has been withdrawn

PAS 91 is a Publicly Available Specification from BSI. BSI describes it as a standard list of the questions typically asked of suppliers at the prequalification stage of construction tendering. The last version, PAS 91:2013+A1:2017, was published on 30 November 2017 and withdrawn on 21 April 2023.¹

Government guidance followed. When the Cabinet Office updated the standard selection questionnaire in PPN 03/24, one of the listed changes was that it removed references to PAS91, which has now been withdrawn by the BSI.²

The name has not disappeared from tender documents, though. Some buyers still write “PAS 91 compliant” out of habit, and some schemes still sell a product built around its modules: CHAS lists “meet the former PAS 91 standard” as part of its Advanced package.³ If a buyer asks for PAS 91, it is worth asking what they actually need. In most cases it is a standard construction PQQ, and the current version of that is the Common Assessment Standard.

SSIP: health and safety, recognised across schemes

SSIP (Safety Schemes in Procurement) does not assess anyone itself. It is an umbrella body whose member schemes all assess health and safety against the same SSIP Core Criteria, which SSIP says are approved by the Health and Safety Executive.⁴ CHAS and Constructionline are both listed among its members.⁵

The useful part for a subcontractor is mutual recognition. Member schemes agree to recognise each other, and joining a second scheme on the strength of the first is called “deem to satisfy”. In SSIP's words, once you have achieved approval through an SSIP Member Scheme, you should never have to undergo assessment with a different Member Scheme.⁴ Some schemes ask for supplementary information when you do this.⁶

Two limits are worth knowing. SSIP covers health and safety only; SSIP itself notes that some member schemes sell extended products covering PAS 91 or the Common Assessment Standard, and that you do not need them if you only need a health and safety assessment.⁷ And SSIP is clear that these third-party assessments are not legally required. They are a way of showing a buyer you meet basic competence, not a licence to work.⁴

The Common Assessment Standard: what most tier 1 contractors now use

The Common Assessment Standard was developed by Build UK. It is an industry-agreed question set with matching assessment standards, and companies are certified once a year by a Recognised Assessment Body. There are two levels of certification, desktop and site-based, and you choose the level that suits your trade, size and clients.⁸ Build UK says more than 21,000 companies are certified to it, and that a certificate is valid for one year from the date of issue.⁹

For civils subcontractors, the list of organisations using it is the important part. Build UK's published list includes Balfour Beatty, Costain, Galliford Try, HS2, Kier, Laing O'Rourke, Skanska, VINCI Construction UK, VolkerWessels UK and Wates, among others.⁸ If those are the names on your order book, CAS is usually what their supply chain teams mean when they ask for pre-qualification.

The Recognised Assessment Bodies are where the scheme names come back in. Build UK lists Constructionline Gold as a desktop certification and Constructionline Platinum as site-based; for Veriforce CHAS, the equivalents are CHAS Elite (CAS) and CHAS Elite (CAS) Assured. Achilles, Compliance Chain, CQMS, SCCS and Smas Worksafe are also recognised.⁸

You only need one. Recognised Assessment Bodies share verified data on 33 key questions, so a contractor can see your certification through whichever body it uses. Build UK also suggests companies check whether they hold CAS from more than one body and whether that is needed for any reason.⁹ Version 6 of the question set is due on 1 November 2026, and micro-businesses are assessed proportionately.⁸

Constructionline levels: what Gold covers

Constructionline sells four verified levels to subcontractors: Bronze, Silver, Gold and Platinum, plus an entry-level Associate membership. Every verified level includes an SSIP assessment from Once For All Health & Safety. Silver adds corporate and professional standing and a health and safety module. Gold is described as all the benefits of Silver and also meeting the Common Assessment Standard, adding equal opportunity and diversity, environmental, quality, BIM, corporate social responsibility and Building Safety Act modules. Platinum adds a one-day premises audit.¹⁰

Prices depend on turnover band. These are the annual fees shown on Constructionline's own pricing tool for a business without an existing SSIP certificate, at the time of writing (October 2026), excluding VAT.¹⁰

If you already hold an SSIP certificate from another scheme, the same tool shows a lower “with DTS Cert” fee, for example £2,449 instead of £2,549 for Gold in the £1 million to £1.5 million band.¹⁰ Check the tool for your own band before budgeting, because the fees change.

CHAS: Standard, Advanced and Elite

CHAS, now trading as Veriforce CHAS, sells three contractor packages. On its own comparison page, Standard meets SSIP requirements, Advanced adds the former PAS 91 standard, and Elite adds the Common Assessment Standard and public sector requirements. At the time of writing (October 2026) it shows Standard from £429 a year, Advanced from £659 a year and Elite from £949 a year, and says costs scale with the size of your organisation.³

Those are starting prices, so a firm with several employees and a seven-figure turnover should expect to pay more; get a quote for your size before comparing it with a Constructionline band. As with any CAS body, the CHAS Elite desktop certificate and the Constructionline Gold certificate are assessed against the same Build UK standard.⁸

What is officially required and what is only requested

None of these schemes is a legal requirement to trade. What matters is who is buying and what their procurement rules let them ask for.

• Central government and the wider public sector. For works contracts run under the Public Contracts Regulations 2015, PPN 03/24 says contracting authorities should use the Common Assessment Standard in place of the standard selection questionnaire.² Under the Procurement Act 2023, Cabinet Office guidance says authorities can continue to use industry questionnaires such as CAS, provided the conditions are proportionate.¹¹
• Equivalents. The same guidance says a condition of participation cannot require particular qualifications without allowing for their equivalents.¹¹ A public buyer naming one scheme should accept an equivalent certificate.
• Frameworks. PPN 03/24 notes that individual call-off contracts under a framework do not need fresh declarations unless the framework terms require them.² The pre-qualification happens when you get onto the framework, which is why it pays to have your certificate in place before the framework opens.
• Tier 1 contractors and private clients. They can ask for whatever they like, and many name a preferred scheme. SSIP's advice is that if a client asks you to join its preferred scheme and you already hold another SSIP certificate, you can use deem to satisfy rather than a full reassessment.⁶

Which one does a small civils firm need?

Most small civils and groundworks businesses fall into one of three positions. Work out which by listing the customers who make up most of your turnover and the pre-qualification each of them actually specifies.

Then work through it in order:

1. List your top five customers and the schemes or standards named in their supply chain packs or frameworks.
2. If every one of them only asks for health and safety, an SSIP assessment from any member scheme is enough.
3. If any of them asks for CAS, Constructionline Gold or CHAS Elite, get CAS desktop from one Recognised Assessment Body. It includes the health and safety assessment.
4. Only move to site-based CAS when a customer asks for it, usually for larger or higher-risk packages.
5. When a second customer names a different body, use CAS data sharing or SSIP deem to satisfy before paying for a second full certificate.

Put the evidence on your website, not only in the portal

A scheme certificate gets you through the gate. It does not get you invited. Supply chain managers and estimators look you up before they send the questionnaire, and if they find a thin website with no accreditations, no project detail and no named people, you may never receive it.

The paperwork you assemble for pre-qualification is also good website content. Most of it is already written; it just lives in a portal no buyer browses.

• An accreditations page listing each certificate, the level and the expiry month, kept current when you renew.
• Policy summaries for health and safety, environment, quality and equality, with the full documents available on request.
• Case studies written out in full: client type, scope, value band, constraints such as possessions or live traffic, and the outcome.
• Service and region pages that match how buyers search, such as “Section 278 works contractor West Midlands”.

We cover the wider picture in digital marketing for civil engineering firms, and the route onto a main contractor's list in how to get on a tier 1 contractor supply chain. If buyers are searching for your services and finding competitors instead, our SEO and GEO service starts by mapping your capabilities and regions to the searches that matter, and a rebuilt website gives the evidence somewhere to live.

Keep it current once you have it

Certification is annual, and lapses are visible. Build UK notes that shared CAS data shows when a company's certification has lapsed because time-critical information such as insurance has not been updated.⁹ A lapsed certificate can quietly drop you off a supply chain list.

Put the renewal date, every insurance expiry and every policy review date in one place with reminders, and update your website's accreditations page the same week you renew. If that information is currently spread across inboxes and spreadsheets, a simple custom system can track it alongside the rest of your operations.