Subcontractor Competence Assessment for Principal Contractors: A Proportionate Approach

TL;DR

• Make a subcontractor competence assessment proportionate: match checks to activity risk, site constraints and trade interfaces, not a one-size-fits-all document pack.
• For principal contractor duties cdm 2015, assess both organisational capability (management/supervision) and individual capability (skills, knowledge and experience).
• Ask for evidence that is job-specific and useful: RAMS with sequencing and interfaces, named supervision, task-relevant training, and plant inspection/certification where applicable.
• Record decisions so they’re defensible: scope, risk band rationale, evidence reviewed (versions/dates), accept/conditions/reject, and clear reassessment triggers.
• Validate competence during the works with targeted site checks (critical controls, supervisor visibility, permits and equipment spot checks), then close out issues.

Note to the reader: The information on this page is for general guidance only. For project specific advice, consult a competent professional.

On one mid-size non-domestic fit-out, a site manager brought two subcontractors through “the usual checks” in an afternoon. A week later, the programme slipped because one crew needed constant rework and another couldn’t provide basic evidence for their planned lifting activity. Nothing dramatic happened, but everyone lost time. The lesson was simple: a subcontractor competence assessment only works when it’s proportionate to the risk and properly recorded.

This guide sets out a practical approach to subcontractor competence assessment principal contractor duties under CDM 2015, focused on non-domestic projects. It’s about making clear, defensible decisions: what to check, how deep to go, what to do when there are gaps, and how to keep records consistent across jobs.

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What “competence” means in a Principal Contractor context (CDM 2015)

In practice, competence is evidence that a subcontractor can plan, manage and deliver their work safely and to the required standard, with the right people, supervision and arrangements in place.

For a Principal Contractor (PC), a competence assessment is not a one-off box-tick. It should:

• Be proportionate to the trade/activity risk and the site constraints.
• Consider organisational capability (management arrangements) and individual capability (skills/knowledge/experience).
• Identify what needs PC supervision or controls to manage residual risk.
• Be recorded so decisions can be explained later without guesswork.

A proportionate assessment: match your checks to the risk

A useful way to keep assessments consistent is to set “bands” of checks based on what the subcontractor will actually do on site. The aim is to avoid two common failures: treating high-risk work like low-risk work, and over-burdening low-risk trades with unnecessary paperwork.

Risk factors to consider before you ask for evidence

• Activity risk: work at height, temporary works, lifting, hot works, confined spaces, live services, structural alterations.
• Site constraints: tight access, live environments, public interface, multiple contractors, restricted egress.
• Interfaces: simultaneous operations and handovers between trades.
• Novelty/complexity: new methods, unusual materials, specialist plant, engineered systems.
• Supervision need: can they self-supervise, or will the PC need to provide closer oversight?

Example evidence requests by risk band

Risk band (typical)	Examples of work	Proportionate competence evidence to request	PC focus during delivery
Lower risk	Basic finishing trades; minor non-invasive tasks; low-risk maintenance in controlled areas	Company H&S policy (short and relevant) RAMS suitable for task Supervisor/lead operative experience summary Training cards where relevant (e.g., abrasive wheels if used)	Induction quality, housekeeping, coordination with others, spot checks on method adherence
Medium risk	MEP install; minor hot works; plant use on site; intrusive works with service risk	RAMS with sequencing and interfaces Evidence of supervision arrangements Competence/training for key tasks (e.g., PASMA, IPAF, hot works) Maintenance/inspection records for relevant equipment Evidence of previous similar work (brief project list)	Permit controls (where used), interface coordination, test/inspection points, active supervision where needed
Higher risk / specialist	Lifting operations; temporary works; structural alteration; complex work at height; confined space; high-voltage environments	Named competent persons (e.g., Appointed Person, temporary works roles where applicable) Detailed plans (lift plan / temporary works designs & checks as relevant) Evidence of competence for critical roles (cards, training, experience) Equipment certification/inspection (LOLER/PUWER as relevant) Emergency arrangements and rescue plans where applicable Strong track record: references or verified examples of similar scope	Hold points, verification of key documents, close coordination, clear change control, supervision intensity matched to risk

What “good evidence” looks like (and what doesn’t)

Evidence should tell you something useful about how the subcontractor will control risk and deliver the work, not just that they own a folder of generic documents.

Useful evidence (practical and site-relevant)

• RAMS that match the job: clear sequence, controls, interfaces, plant, access, lifting/temporary works needs, and who is supervising.
• Role-based competence: training/qualifications for the tasks being done (not a scattergun list).
• Supervision arrangements: named supervisor, ratios, and how they monitor standards.
• Equipment suitability and inspection: relevant certificates and inspection regimes for what will be used on your site.
• Experience evidence: short list of comparable projects, including similar hazards and constraints.
• Accident/near-miss learning: signs they actually learn and improve (brief, factual examples).

Red flags to watch for

• Generic RAMS with no site constraints, no sequencing, no interfaces, and no named supervision.
• Over-reliance on cards with no explanation of how work will be planned and managed.
• “We always do it this way” language when the job is clearly different.
• Missing critical roles (e.g., no clear responsibility for lifts/temporary works where relevant).
• Certificates that don’t match the plant arriving on site (or are out of date).
• Frequent last-minute change of supervisor or crew without any re-check.

How to document the assessment (so it stands up on a busy project)

A proportionate assessment still needs a consistent record. The goal is to show: (1) what was assessed, (2) what evidence was reviewed, (3) what the decision was, and (4) what controls/supervision were put in place.

A simple decision record structure

• Scope of works: what the subcontractor is doing (and not doing).
• Risk band rationale: why you treated it as low/medium/high risk.
• Evidence reviewed: list documents and key dates/versions (RAMS ref, training evidence, inspection certs).
• Decision: accepted / accepted with conditions / not accepted (with short reason).
• Conditions and controls: supervision level, permits, hold points, briefing requirements, interface coordination actions.
• Reviewer: who checked it (role) and when.
• Reassessment triggers: what would cause re-check (scope change, new plant, new supervisor, change in method).

Keep competence records consistent across projects

Consistency doesn’t mean “copy and paste.” It means you can quickly see what’s been checked and what’s still valid.

• Use the same headings across projects (scope, risk band, evidence, decision, controls, review date).
• Version control RAMS and record which version was approved for the job.
• Separate “company-level” and “project-level” evidence (policy vs job-specific RAMS and supervision).
• Set sensible review points: start of works, major programme change, or a material change in method or personnel.
• Link to site briefings: record that key controls were briefed (and to whom) without drowning in signatures.

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Managing gaps: accept with conditions, or pause until resolved

Not every gap means “reject the subcontractor.” The practical question is whether the gap can be controlled by changing the plan, increasing supervision, or obtaining missing evidence before the relevant task starts.

Common gaps and workable controls

• Limited experience in a specific environment (e.g., live site): increase PC coordination and supervision; add more structured briefings and daily coordination.
• RAMS not site-specific: return for revision with clear points to address (access, sequencing, interfaces, plant, rescue where relevant).
• Training evidence incomplete: restrict tasks until competent persons are in place; verify competence for the specific activity rather than requesting everything.
• Unclear supervision: require a named supervisor and set expectations for presence, inspections, and stop-work authority.
• New or substituted plant: confirm suitability and inspection before use; brief operatives on changes; update RAMS.

When to reassess immediately

• Scope expands into higher-risk work (e.g., intrusive works become structural).
• Key personnel change (supervisor, appointed roles for high-risk activities).
• Method changes materially (different access method, different lifting approach, different sequencing).
• Repeated non-conformance indicates the planned controls are not being implemented.

Practical site checks that confirm competence during the works

Paper tells you what should happen; site checks tell you what is happening. A proportionate approach uses targeted checks aligned to the risk.

• Start-of-shift check: brief confirmation that the crew understands the job, constraints and interfaces.
• Supervisor visibility: confirm supervision is as stated in the assessment.
• Critical control verification: e.g., edge protection in place, exclusion zones, service isolation, permit controls being followed.
• Plant and equipment spot checks: right equipment, right condition, evidence available where expected.
• Learning loop: capture issues, close them out, and update controls where needed.

FAQs

What is a subcontractor competence assessment for a Principal Contractor?
It’s a risk-based check that a subcontractor has suitable organisational arrangements and capable people to carry out their scope safely on your site, and that the evidence (RAMS, supervision, training, equipment suitability) supports that decision.

 

How do Principal Contractors assess competence proportionately under CDM 2015?
By matching the depth of checks to the actual risk: lower-risk trades may only need clear task-specific RAMS and basic training evidence, while higher-risk or specialist work needs named competent roles, detailed plans (where applicable), and stronger verification of equipment and supervision arrangements.

 

What evidence should a PC ask a subcontractor for?
Start with job-specific RAMS and supervision arrangements, then add task-relevant competence evidence (cards/qualifications), equipment inspection records where relevant, and brief examples of similar work. The key is relevance to the planned activities and site constraints, not the biggest document pack.

 

Can a subcontractor be accepted if something is missing?
Often yes, if the gap is controlled: you can accept with conditions (e.g., restrict certain tasks, increase supervision, require RAMS revisions, verify inspections before use) provided those conditions are clear, recorded, and implemented before the relevant work starts.

 

How should competence decisions be recorded across multiple projects?
Use a consistent structure: scope, risk band rationale, evidence reviewed (with versions/dates), decision, conditions/controls, reviewer and review date, plus clear reassessment triggers. Keep company-level evidence separate from project-level evidence so updates are easier to manage.

 

Does the Principal Contractor take on the subcontractor’s legal duties by checking competence?
No. The PC is managing and coordinating the work and needs to make reasonable checks and arrangements under CDM 2015, but each duty holder remains responsible for their own duties.

Summary

A strong subcontractor competence assessment principal contractor process is simple in principle: assess the real risk, ask for evidence that matches that risk, record the decision and any conditions, then confirm on site that the controls are actually being used. Done well, it saves time, reduces rework, and makes coordination calmer and more predictable.

CTC supports compliance; legal duty remains with duty holders.

How we can help: If you want a practical, consistent way to assess subcontractor competence across projects (without overcomplicating it), speak to CTC about aligning your evidence checks, recording approach and site verification routines.

Disclaimer

This resource is provided for general guidance only. Always consult a competent professional for project specific advice. No warranty or guarantee is given or implied regarding completeness, accuracy, or compliance.

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