CDM 2015 and subcontractor documents: what UK principal contractors need to collect and keep

What CDM 2015 actually requires of a principal contractor

The Construction (Design and Management) Regulations 2015 apply to most construction projects in Great Britain, particularly where more than one contractor is involved. As principal contractor, your core duties around subcontractors include:

• Appointing only contractors who are competent to carry out the work safely
• Ensuring each contractor has the health and safety information they need before work begins
• Coordinating health and safety across the construction phase
• Maintaining a construction phase plan that reflects actual site conditions and work

The regulations do not prescribe a specific list of documents you must collect. What they require is that you can demonstrate, if asked, that the subcontractors you engaged were suitably qualified and that appropriate safety management was in place.

In practice, that means holding documentary evidence. Competence cannot be assumed. If something goes wrong on site and you cannot show that your subcontractors had the appropriate qualifications and valid insurance cover, your position as principal contractor becomes significantly more difficult.

Which subcontractor documents are commonly used for CDM 2015 checks

CDM 2015 does not contain an official document list. What most UK contractors collect, and what CDM audits commonly involve, is a set of documents that together serve as supporting evidence of competence and valid cover.

The following documents are commonly used for CDM 2015 checks:

• CSCS card (or equivalent trade card such as ECS, CPCS, or CISRS) for each operative
• Public Liability Insurance certificate, with cover level confirmed against site requirements
• Employers Liability Insurance certificate (required by law where the subcontractor employs staff)
• Risk Assessment and Method Statement (RAMS) specific to the work being carried out
• LOLER and PUWER inspection records for any plant or equipment brought to site
• COSHH assessments where hazardous substances are involved
• SSIP accreditation such as CHAS or SafeContractor (where required by the client or principal designer)

The key qualifier is relevance. A RAMS document from a previous project, a CSCS card for an operative in a different role, or an insurance certificate that has since lapsed does not serve as supporting evidence of current competence. Each document needs to be relevant to the actual work and valid at the time it is being relied upon.

For a full breakdown of each document type and what to check for on each one, see the subcontractor compliance checklist.

Who counts as a principal contractor, and when does CDM 2015 apply?

CDM 2015 applies to virtually all construction work in Great Britain. A principal contractor is appointed when a project involves more than one contractor. If you are engaging or employing subcontractors on a construction project, you are almost certainly either acting as principal contractor or working under one.

One common source of confusion is scope. Many smaller contractors assume CDM only applies to large or formally notifiable projects. The 2015 regulations removed the previous size threshold that triggered certain requirements. Today, even relatively small projects fall within scope where more than one contractor is involved.

For notifiable projects (broadly, those lasting more than 30 working days with more than 20 workers simultaneously, or exceeding 500 person-days in total) additional duties apply, including formal appointment of a principal designer and notification to the HSE.

If you manage subcontractors but are unsure whether you hold the principal contractor role, the appointment should be confirmed in your contract with the client. If the client has not formally appointed a principal contractor and there is more than one contractor on site, that is a gap in the CDM structure with its own risks.

What contractors are often asked to show

The following reflects what tends to come up when CDM arrangements are reviewed in practice. It is not a statement of specific legal requirements, and individual projects, clients, and principal designers may have different expectations.

When a project is audited by a principal designer, or when CDM arrangements are reviewed on site, the documents most commonly asked for are the ones that speak directly to operative competence and active safety management. In practice, that tends to mean:

• Valid trade cards for operatives currently working on site, not just those present at mobilisation
• Current insurance certificates for each subcontractor actively carrying out work
• RAMS that are specific to the current scope of work, not a generic or reused document
• Up-to-date inspection records for any lifting equipment in active use

The detail that tends to surface issues is currency, not whether documents were collected. A CSCS card gathered at mobilisation that expired two months later, or an insurance certificate that lapsed mid-contract, is the kind of gap that tends to appear at the least convenient moment. The documents were there. They just were not being tracked.

Keeping your CDM document records in order

CDM 2015 is not a one-time exercise at the start of a project. The duty to ensure your subcontractors remain competent and properly insured runs throughout the construction phase. A document that was valid at mobilisation needs to still be valid as the project continues.

Most contractors find that expiry dates are where the system breaks down. Documents get collected, filed somewhere, and then forgotten. Six months into a project, an insurance certificate lapses quietly. A CSCS card expires. Nobody notices because nobody was tracking the dates.

Collecting documents and tracking documents are two separate tasks. Collecting gets you through mobilisation. Tracking is what keeps you covered throughout.

Whether you use a spreadsheet, a shared folder, or a purpose-built tool, the principle is the same: record the expiry date alongside the document, and make sure someone reviews it before something lapses rather than after.

ExpiryFlow tracks every expiry date across your subcontractor supply chain and sends automatic reminders at 30, 7, and 1 day before anything expires. Add your subcontractors, upload their documents, and the system monitors the dates so you do not have to.

Common questions about CDM 2015 and subcontractor documents

Track your CDM documents automatically

ExpiryFlow tracks CSCS cards, insurance certificates, RAMS, and more for every subcontractor. Automatic reminders at 30, 7, and 1 day before anything expires.

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