Common Assessment Standard Cost: What CAS Certification Actually Costs a Subcontractor

A main contractor has asked you for the Common Assessment Standard and you want one number. There isn't one — and the reason why is the single most useful thing to understand before you pay anybody. The Common Assessment Standard cost you end up with is not a fee for CAS itself; it's the price of the top-tier membership sold by whichever assessment body you certify through, and those prices differ by hundreds of pounds for the same certificate.

TL;DR

The Common Assessment Standard is a question set owned by Build UK, not a product you buy from Build UK. You get certified by one of seven Recognised Assessment Bodies, and you pay that body's top package. The clearest published figure as of 26/08/2026 is CHAS Elite, which includes CAS, from £909 a year — against CHAS Standard (SSIP only) from £429, so the CAS step-up is roughly £480 a year at the entry band. Constructionline Gold (the CAS desktop route) is priced by turnover band and quoted at sign-up rather than published as a flat figure; most other bodies quote too. You only need to certify with one body per year — Build UK's data sharing means you should never pay twice to be visible to a second body's clients.

Why is there no single Common Assessment Standard price?

Build UK developed and maintains the Common Assessment Standard, but it does not certify anybody. According to Build UK, companies are "certified once a year by a Recognised Assessment Body", and there are two levels of certification: desktop and site-based. Build UK currently lists seven Recognised Assessment Bodies, each selling CAS under its own product name.

That structure is why the cost varies. You are buying a commercial membership — portal access, client visibility, perks, support — that happens to include the CAS audit. Two firms with identical paperwork can pay very different amounts depending purely on which door they walked through.

How much does CHAS Elite cost for the Common Assessment Standard?

CHAS publishes "from" prices for all three of its contractor packages, which makes it the cleanest benchmark available. As of 26/08/2026, CHAS lists Standard from £429 a year, Advanced from £659 a year, and Elite — the package that meets Common Assessment Standard requirements — from £909 a year, all excluding the effect of company size on the band you actually land in.

The useful number here is the gap, not the total. Moving from CHAS Standard to CHAS Elite at the published entry bands is about £480 a year of extra spend for the same firm — that is what CAS costs you on top of the SSIP certificate you probably already hold. Frame every quote you get that way, because £480 a year against one recurring commercial maintenance contract is a straightforward sum to do at the kitchen table.

CHAS also states on its Common Assessment Standard page that businesses with fewer than five employees and turnover under £500,000 get streamlined assessment criteria. Build UK makes the same point at standard level: for companies meeting the criteria for a micro-business, the assessment standards are applied proportionately. Sole traders and two-man bands should say so up front — you are not being assessed as though you were Kier.

What does Constructionline Gold cost for CAS?

Constructionline is the other body most subcontractors get pointed at, and its structure is worth knowing precisely. Constructionline confirms that the CAS desktop audit corresponds to Gold and the site-based audit to Platinum, and that a CAS certificate is valid for 12 months from issue. Constructionline's supplier FAQs state that suppliers pay an annual fee based on turnover, that membership starts "from as little as £399 a year" (that is the entry level, not Gold), and that there is a one-off joining fee for new members based on turnover band, with only the annual fee payable from year two.

In practice, that means the Gold price you are quoted depends on which of fifteen turnover bands you fall into. There is no published Gold figure to quote here, so treat any number you see on a third-party blog with suspicion and get it from the sign-up flow.

Desktop or site-based — which CAS level do you actually pay for?

This is the second big cost lever, and plenty of subcontractors buy the wrong one. Build UK says companies apply for the level "most appropriate for their business" based on trade, size and what their clients demand.

Worked example: a 12-engineer M&E firm asked for CAS

Say you run a twelve-engineer electrical and mechanical firm, you already hold an SSIP certificate, and a main contractor tells you that from your next renewal you need the Common Assessment Standard before you set foot on site.

1. 1
   Ask which level, and who accepts it. Build UK's own position is that a growing list of contractors and clients accept CAS from any Recognised Assessment Body and "no longer specify a particular assessment body". Get that confirmed by your buyer in an email — if they'll take any RAB, you can shop on price.
2. 2
   Price your current body's top tier first. If you're already a CHAS member, the arithmetic is the £429-to-£909 step (published entry bands, checked 26/08/2026) rather than a whole new membership.
3. 3
   Get two more quotes with your real numbers. Twelve employees and your last filed turnover figure. Both drive the band. Ask explicitly whether a joining fee applies in year one and what the year-two renewal will be.
4. 4
   Reuse your SSIP. Your existing SSIP certificate can satisfy the health and safety element rather than being bought again — but it does not deliver CAS. The other sections still have to be answered and evidenced.
5. 5
   Certify once, then share the data. Build UK's FAQs state companies only need to be certified once a year by a single Recognised Assessment Body, because they can share their pre-qualification data with the others to be visible to more clients.

On published figures, the honest answer for that firm is: budget roughly £900–£1,200+ a year for the CAS tier, expect the exact figure to be band-driven, and expect the incremental cost over your existing SSIP-only membership to be a few hundred pounds rather than a four-figure shock. TODO(verify) the exact CHAS employee band and the Constructionline Gold band figure at the point of purchase — neither is published as a full table.

Where the real cost hides: renewals and the tiers nobody passports

The fee is the part everyone quotes. The part that quietly costs more is the calendar.

CAS is certified once a year, and a CAS certificate runs 12 months from the date of issue. SSIP mutual recognition (Deem to Satisfy) is genuinely useful for the health and safety element, but it does not passport CAS itself, and it does nothing about client-specific PQQs or the higher tiers. So a firm that holds an SSIP certificate, a CAS certificate through one body, and a client portal registration somewhere else is now managing three renewal dates and re-uploading the same insurance schedule, H&S policy and training matrix into three portals.

Build UK's data sharing helps with visibility, not admin: to share your data you complete that body's data sharing form and email the body that originally certified you to give permission. It is a per-body task, not a switch.

One more freshness point worth diarising: Build UK has confirmed that Version 6 of the Common Assessment Standard question set will be published on 1 November 2026. If your renewal falls after that date, expect the question set — and the evidence your assessor asks for — to have moved. Read our breakdown of the Common Assessment Standard question set before you start filling anything in.

Is the Common Assessment Standard worth paying for?

Only if a buyer is asking, or you're chasing public sector work. Build UK's FAQs report over 21,000 companies across the supply chain certified to CAS, and its published list of organisations using it runs from Balfour Beatty and Kier to SCAPE, YPO and HS2. Build UK also states that central government departments and wider public sector bodies should use CAS to pre-qualify suppliers in accordance with PPN 03/24. Both Constructionline and Smas Worksafe describe that as applying above a contract threshold of £5.337 million — check the PPN itself before relying on the threshold for a specific bid, and speak to the buyer or a procurement professional about your particular contract.

If nobody has asked and you don't tender for public work, an SSIP certificate remains the cheaper gate. Compare the ladder in our guides to CHAS costs, Constructionline Gold cost and requirements and what SSIP mutual recognition does not cover, or start from the scheme comparison hub if you're still deciding. And whichever route you take, put the renewal date somewhere you'll actually see it — our accreditation renewal deadlines guide covers the cycle for each scheme.

Frequently Asked Questions

How much does the Common Assessment Standard cost?

There is no single CAS fee, because Build UK licenses the standard to Recognised Assessment Bodies who each price their own package. The clearest published figure as of 26/08/2026 is CHAS Elite from £909 a year; Constructionline Gold and most other bodies quote by turnover or employee band rather than publishing a flat price.

Do I need to get CAS certified with more than one assessment body?

No. Build UK's FAQs state that companies only need to be certified once a year by a single Recognised Assessment Body, because certified companies can share their pre-qualification data with the other bodies so it is visible to more contractors and clients. If a buyer insists you appear on a second body's portal, ask about data sharing before you buy a second certification.

Does my SSIP certificate cover the Common Assessment Standard?

No. SSIP Deem to Satisfy can be used to evidence the health and safety element — Constructionline, for example, accepts an existing SSIP certificate as Deemed to Satisfy towards Gold — but CAS covers far more ground than health and safety, and the remaining sections still have to be answered and evidenced.

What's the difference between the desktop and site-based CAS certification?

Build UK operates two CAS certification levels: desktop, where a Recognised Assessment Body verifies your answers and evidence remotely, and site-based, where an auditor visits your premises. Desktop is the cheaper and more common route for small subcontractors; only choose site-based if a client specifically requires it.

How long does a Common Assessment Standard certificate last?

Twelve months. Build UK states that companies are certified once a year, and Constructionline confirms that once a desktop or site CAS audit is verified, the certificate is valid for 12 months from the date of issue — so the renewal work comes round annually.

Last reviewed 26/08/2026. Prices and question set versions change; this page is informational only, not compliance advice. Check the figure with the assessment body before you buy, and speak to the scheme or a professional about anything specific to your contract.