CDM 2015 Core · Mandatory · Pre-Construction

Competence Assessment — Subcontractor

This assessment verifies that a subcontractor possesses the necessary skills, knowledge, and organisational capability to carry out their work safely under CDM 2015. It evaluates health and safety policies, method statements, training records, and relevant trade accreditations before any work package is awarded.

Last reviewed: 29 March 2026 — This guide reflects UK law as of this date. CDM 2015 Reg 8 remains current with no amendments enacted as of 29 March 2026. Next scheduled review: 29 March 2027.

Legal basis	CDM 2015 Regulation 15(7) — contractor must not appoint a person unless they have (or are obtaining) the skills, knowledge, training and experience to carry out allocated tasks safely
Who must check	Any contractor who employs or engages workers, or appoints sub-subcontractors to work on site
Different from Guide #10	Guide #10 covers the PC checking contractors (Reg 8(3)). This guide covers the contractor checking their own workers and sub-subcontractors (Reg 15(7)).
Primary evidence (workers)	CSCS cards, trade qualifications, task-specific training records, specialist certifications
Primary evidence (organisations)	SSIP accreditation, relevant experience, insurance, RAMS
When	Before the worker arrives on site or the sub-subcontractor starts work
Applies to	Employees, self-employed workers, labour-only gangs, and any sub-subcontractor the contractor engages

1. What Is This Assessment and Who Needs to Do It?

When a contractor (who is themselves working as a subcontractor to the Principal Contractor) engages their own workers or appoints sub-subcontractors, they take on a legal duty to check that those individuals or organisations have the competence to carry out the tasks they will be allocated.

This is a separate and distinct duty from the PC's competence check on the contractor under Regulation 8(3). It operates one level lower in the supply chain and focuses more on individual workers and their task-specific qualifications than on organisational health and safety management systems.

“15(7) A contractor must not employ or appoint a person to work on a construction site unless that person has, or is in the process of obtaining, the necessary skills, knowledge, training and experience to carry out the tasks allocated to that person in a manner that secures the health and safety of any person working on the construction site.”— CDM 2015 Regulation 15(7)

Where this sits in the CDM supply chain

The CDM competence checking obligation cascades through every level of the supply chain. Client checks PC (via Reg 8(3)). PC checks each contractor they appoint (via Reg 8(3)). Each contractor checks the workers and sub-subcontractors they deploy (via Reg 15(7)). At each level, the appointing party is responsible for checking those directly below them. The PC's checks on the contractor do not substitute for the contractor's own checks on their workers. Each duty holder remains responsible for the people they control.

2. Regulation 8(3) vs Regulation 15(7) — The Key Difference

Both regulations concern competence — but they operate at different levels of the supply chain and focus on different things. Understanding the distinction matters because the evidence required and the formality of the assessment is different for each.

	CDM 2015 Reg 8(3) PC checking contractors	CDM 2015 Reg 15(7) Contractor checking their own workers
Who the duty falls on	PC (or client appointing PC)	Contractor appointing their own workers or sub-subcontractors
Who is being assessed	The contractor/subcontractor organisation	Individual workers, and sub-subcontractor organisations
What it requires	Reasonable steps to check the appointee has the skills, knowledge, experience and organisational capability required	Must not employ or appoint a person unless they have (or are obtaining) the skills, knowledge, training and experience to carry out the tasks allocated safely
Level of formality	Formal assessment — documented record, SSIP/CAS check, RAMS review	Proportionate — from brief CSCS card check for a single worker to a fuller assessment for a sub-subcontractor organisation
Primary evidence	SSIP certificate, CAS accreditation, organisational H&S management systems	CSCS cards, trade qualifications, specialist certifications, task training records
Documented record	Yes — formal competence assessment record before appointment	Yes — even a brief record of what was checked and when

The practical effect is that a contractor's competence assessment under Regulation 15(7) is typically less formal than the PC's Regulation 8(3) assessment — but it is no less legally required. The depth should be proportionate to the risk of the tasks being allocated.

3. CSCS Cards — The Primary Worker-Level Evidence

The Construction Skills Certification Scheme (CSCS) is the industry-standard mechanism for demonstrating that individual construction workers have achieved the qualifications and training appropriate to their trade. While CSCS cards are not a statutory requirement under CDM 2015 itself, they are widely mandated by principal contractors as a condition of site access — and they are the most practical and portable evidence of worker-level competence available.

Card colour	Level	What it means	Typical holders
Green	Labourer / Trainee	Site Operative NVQ or Health and Safety Awareness course. For non-specialist site labourers and those working towards a trade qualification.	General site labour, material handling, basic plant operations under supervision
Blue	Skilled Worker	NVQ/SVQ Level 2 in the relevant trade, or equivalent. The most common card for qualified tradespeople.	Bricklayer, carpenter, electrician, plumber, painter, plasterer — all qualified at Level 2
Gold	Advanced Craft / Supervisor	NVQ/SVQ Level 3 in the relevant trade, or SMSTS/supervisory qualification. For experienced tradespeople and site supervisors.	Advanced craftspeople, working supervisors, gang leaders
Black	Manager	NVQ Level 6/7 or professional qualification. For construction managers.	Project managers, site managers, construction managers
White	Professionally Qualified	Degree or professional qualification. For professionals not covered by another card scheme.	Architects, engineers, surveyors, CDM advisors on site
Red	Experienced Worker / Apprentice	Temporary card for those with substantial site experience or formal apprenticeship without full NVQ. Time-limited.	Experienced workers pursuing NVQ, apprentices in training

Verifying a CSCS card is genuine and current

Do not just accept a card on trust. Cards can be expired, belong to someone else, or be fraudulent. Verify every card using the CSCS Card Checker app (free from the CSCS website) or at cscs.uk.com. The checker confirms the card is genuine, current, and belongs to the individual presenting it. Record the verification — a note of the card number, expiry date, and date checked is sufficient.

4. Specialist Certifications Beyond CSCS

For certain trades and activities, CSCS cards alone are insufficient. Additional specialist certifications confirm competence for specific high-risk activities. The contractor must check these before allowing the relevant work to start.

Certification	Applies to	Notes
Gas Safe Register	Gas work of any kind — boilers, heating, pipework	Legally required — must be verified before any gas work starts
NICEIC / ECA registration	Electrical installation and testing	Effectively mandatory — most clients and insurers require it
IPAF	Powered access platforms (cherry pickers, scissor lifts, etc.)	Required for operating MEWPs; check card is current and covers the equipment type
PASMA	Mobile access towers and scaffold towers	Required for assembly and use; PASMA card confirms training
CPCS / NPORS	Plant and machinery operation — excavators, cranes, telehandlers, etc.	CPCS (blue card) or NPORS with endorsement; check category matches the plant being used
UKATA / Licensed Asbestos	Asbestos removal and encapsulation	HSE-licensed contractor required for licensed asbestos work. Asbestos awareness for all others.
SMSTS / SSSTS	Site management / supervisory safety training	Not legally required but widely expected for supervisors; CITB-accredited
First Aid at Work	Designated first aider on site	Required where site rules mandate first aid cover; check certification is current

Gas Safe and electrical registration — not optional

Gas work of any kind must be carried out by a Gas Safe registered engineer. This is a statutory requirement under the Gas Safety (Installation and Use) Regulations 1998, not just a CDM matter. Similarly, NICEIC or ECA registration is required for notifiable electrical installation work under Part P of the Building Regulations. The contractor must verify registration before gas or electrical work starts — not after. A CSCS card does not substitute for these mandatory trade registrations.

5. When You Appoint a Sub-Subcontractor Organisation

Where a contractor appoints another organisation — a sub-subcontractor — rather than individual workers, the competence check needs to assess both the organisation's management capability and the competence of the individuals they will deploy. The same two-level framework from Guide #10 applies here, scaled proportionately to the risk.

For a sub-subcontractor organisation, check:

SSIP accreditation — verify as current via the SSIP portal, not just from a certificate provided by the contractor
Relevant experience — their SSIP covers general H&S, but does it cover this type of work? A scaffolding firm's SSIP doesn't confirm competence for specialist groundworks.
Public liability insurance — minimum £1m, ideally £2m+ for most trades; confirm level appropriate to the scope
Employer's liability insurance — mandatory for any employer; minimum £5m statutory
Trade-specific registrations — Gas Safe, NICEIC, CPCS endorsements, etc. as relevant to the scope
Project-specific RAMS — required before they start; check these are genuinely specific to the work, not generic templates
Named supervisor — who will be responsible for their workers on site?

Notify the PC before sub-subcontracting

Many PC appointment letters and subcontract terms include a clause requiring the contractor to notify the PC before appointing sub-subcontractors. This is good CDM practice — the PC needs to know who is on site and must coordinate all contractors' activities. Check your appointment terms and notify the PC of any sub-subcontractor appointments, providing the same basic details that would appear in the Duty Holder Register.

6. Practical Checklist — Before and During Works

The following checklist covers the minimum checks a contractor should carry out and document for workers and sub-subcontractors under their control. Scale the depth to the risk — a specialist high-risk sub-subcontractor warrants more rigorous checks than a labourer joining a low-risk task.

Before engaging a sub-subcontractor organisation:

SSIP accreditation confirmed current (check ssip.org.uk directly)
Relevant trade experience confirmed — not just general H&S accreditation
Public liability and employer's liability insurance levels confirmed
Specialist trade registrations confirmed (Gas Safe, NICEIC, CPCS, etc.)
Project-specific RAMS requested and reviewed before start date confirmed
Named supervisor identified for their scope of work

Before a worker arrives on site:

CSCS card checked — colour appropriate to their trade and qualification level
Card is in date and belongs to the individual presenting it
Any specialist certifications relevant to their tasks checked (IPAF, PASMA, etc.)
Site induction arranged — either through PC or by contractor for their workers
Task-specific briefing completed where RAMS require it

Ongoing during the works:

CSCS cards re-verified if new workers arrive during the project
Any changes to the sub-subcontractor's scope flagged to PC and reassessed
Concerns about worker competence escalated to PC immediately
Supervision arrangements checked remain adequate as works progress

7. Common Mistakes

Assuming the PC’s competence check covers your workers too

The PC’s Regulation 8(3) check covers your organisation — your management systems and capability. It does not cover every individual worker you deploy. Under Regulation 15(7), you remain responsible for checking that each person you send to site has the skills, knowledge, training and experience for their allocated tasks. The PC’s check does not discharge this duty for you.

Accepting a CSCS card without verifying it is genuine and current

A CSCS card that is expired, in the wrong name, or forged provides no assurance. Verify every card using the CSCS Card Checker app. Record the verification. The HSE considers production of a forged or expired CSCS card on site as evidence of a competence failure — and the contractor who accepted it without checking shares responsibility for that failure.

Sending workers with a Green (labourer) card to do skilled work

A Green CSCS card confirms only basic site H&S awareness — not trade competence. A worker with a Green card should not be laying brickwork, doing first fix plumbing, or carrying out any trade-specific task. The card colour must match the work being done. Using labourers for skilled work to cut costs is both a competence failure under Regulation 15(7) and a quality/liability risk.

Not checking specialist certifications before specialist work starts

Allowing gas work to start before verifying Gas Safe registration, or MEWP operation before checking IPAF certification, is a Regulation 15(7) failure. These checks must happen before the work starts — not on the day, not after. Build the check into your pre-start routine for any scope involving specialist high-risk activities.

Sub-subcontracting without notifying the PC

Many principal contractors’ site rules and subcontract terms require notification before sub-subcontracting. Failing to notify the PC means they cannot coordinate the additional party’s activities, include them in site inductions, or update the CPP and Duty Holder Register. It may also breach your contractual obligations. Always notify the PC before appointing a sub-subcontractor.

Not recording what was checked

An unrecorded competence check is no check at all in terms of demonstrating compliance. A brief note — worker name, CSCS card number and expiry, specialist certification reference, date checked — takes two minutes and provides the only evidence that the Regulation 15(7) duty was discharged. Keep these records for the duration of the project and beyond.

8. Related Documents

Document	Relationship
Competence Assessment — Contractor	Guide #10 covers the PC’s competence check on contractors under Regulation 8(3). This guide covers the contractor’s check on their own workers and sub-subcontractors under Regulation 15(7). Both must be completed — they operate at different levels.
Contractor Appointment Letter	The contractor appointment letter (from PC to contractor) should include an obligation for the contractor to carry out and document Regulation 15(7) checks on their own workforce and any sub-subcontractors they appoint.
Construction Phase Plan	The CPP should reference site induction and competence verification arrangements. Where a contractor appoints sub-subcontractors, the PC may need to update the CPP to reflect their involvement.
Site Induction Record	Site induction is part of the Regulation 15(7) information and instruction obligation. Every worker must receive a site induction — either via the PC’s arrangements, or provided by the contractor for their own workers. Both should be recorded.
CDM Duty Holder Register	Sub-subcontractors who hold a CDM contractor role should be added to the project duty holder register. The contractor should notify the PC of their appointment so the register can be updated.

9. Frequently Asked Questions

Is CSCS a legal requirement under CDM 2015?▾

CSCS cards are not explicitly required by CDM 2015 itself. However, CDM 2015 Regulation 15(7) requires contractors to check that workers have the skills, knowledge, training and experience for their tasks — and CSCS cards are the most practical and universally accepted evidence of that for most trades. Most principal contractors mandate CSCS as a condition of site access via their CPP site rules. Practically, on most commercial and public sector sites in the UK, CSCS cards are a de facto requirement.

What if a worker doesn’t have a CSCS card but is clearly experienced?▾

Experience alone does not satisfy Regulation 15(7) — the regulation requires skills, knowledge, training and experience. A worker without a CSCS card cannot demonstrate they have achieved the formal training and assessment required for their trade. The correct approach is to apply for the appropriate CSCS card. If a card is being applied for or renewed, some principal contractors allow a grace period with documented interim evidence — but this is at the PC’s discretion and must be agreed in advance.

Can I sub-subcontract without informing the PC?▾

You should always check your appointment letter and subcontract terms — most will require PC notification before sub-subcontracting. Even if your contract doesn’t explicitly require it, CDM 2015 requires the PC to plan, manage and coordinate all construction work on site. A sub-subcontractor who arrives unannounced disrupts that coordination and may not have received site induction. Always notify the PC before a sub-subcontractor starts.

What’s the difference between checking a worker and checking a sub-subcontractor?▾

Checking an individual worker focuses on their personal qualifications, CSCS card, and task-specific training. Checking a sub-subcontractor organisation involves both an organisational check (SSIP, insurance, H&S management systems) and a worker-level check (CSCS cards and certifications for the individuals they will deploy). Both levels must be addressed when engaging an organisation.

Do I need to check competence again if a worker has been on this site before?▾

If a worker returns to the same project after a break, their CSCS card expiry should be re-verified if it was close to expiry last time. Their site induction may need to be refreshed if site conditions have changed significantly. For workers moving between projects, the competence check starts again on each new project — CSCS card verification and any new project-specific task training.

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