How to Manage Subcontractors in Construction
The four systems a principal contractor needs to control subcontractor risk, prequalification, contract, competence and the audit trail, and where most site teams can survive a spot check but not an audit.
Most UK construction work is not done by the company whose name is on the hoarding. It is done by subcontractors, often several tiers of them, supplied through agencies and self-employment arrangements that shift from project to project. That is not a criticism of the model. It is how the industry delivers at scale. But it means the principal contractor carries legal responsibility for people it does not employ, does not induct directly in most cases, and often cannot see past the second tier.
Subcontractor management is the discipline of closing that gap. Not paperwork for its own sake, but the systems that let a principal contractor say, with evidence, who is on site, what they are approved to do, and whether they are competent to do it.
This guide covers the four parts of subcontractor management that matter: prequalification, contract and insurance, competence on site, and performance and payment. It also covers where the process breaks down in practice, and the routine that keeps it live rather than filed away.
Why This Is a Principal Contractor Problem, Not a Procurement One
Under the Construction (Design and Management) Regulations 2015, Regulation 13 places a clear duty on the principal contractor: plan, manage, monitor and coordinate the construction phase, and check that anyone appointed has the necessary skills, knowledge and experience before they start work. That duty does not stop at your direct subcontractors. It follows the work down the chain.
The Building Safety Act 2022 goes further. Principal contractors are expected to take all reasonable steps to ensure that subcontractors, across every tier, meet building safety competence requirements, and the Act applies to building work generally, not only higher-risk buildings. It also widens what "competence" means beyond the CDM 2015 test of skills, knowledge and experience to include behaviour, the same SKEB standard (Skills, Knowledge, Experience, Behaviours) that sits behind workforce readiness. Our guide to workforce readiness in UK construction sets out that standard in full.
The Four Parts of Subcontractor Management
Before a subcontractor is appointed, you need evidence they meet a baseline standard for health and safety, insurance and financial stability. SSIP (Safety Schemes in Procurement) is the umbrella that CHAS, Constructionline and other accreditation schemes sit under, and its mutual recognition principle means health and safety approval from one member scheme should be accepted by the others rather than reassessed from scratch.
The Common Assessment Standard, developed by Build UK with Constructionline and the SSIP schemes, is now the reference framework most Tier 1 contractors ask their supply chain to meet. Since October 2025, major Build UK members including Galliford Try, Kier, Mace, Morgan Sindall and VINCI have required subcontractors to complete the Building Safety section of the standard, not just the core health and safety questions, before they will work with them.
Prequalification answers one question: is this a competent organisation, in principle, before any work has started. It says nothing about the individual workers that organisation sends to your site next Monday.
The subcontract, typically a JCT or NEC form, is where prequalification becomes enforceable. It should set out the competence and training standards you expect, the insurance levels required (public liability, employer's liability, professional indemnity where relevant), and the health and safety information the subcontractor must provide before mobilisation, including their input to your construction phase plan.
Payment terms sit here too. The Construction Act 2011 amendments outlawed "pay when paid" clauses, so a subcontractor's right to payment cannot be made conditional on you being paid by someone further up the chain. Retention, typically 3 to 5 percent of contract value held until defects are resolved, is currently standard practice, but it is under active legislative challenge: the government introduced the Commercial Payments Bill in May 2026 with provisions that would ban retention deductions in construction contracts. That is not yet law. Treat it as a change to plan for, not a change you can rely on today.
This is where prequalification and contract terms either become real or stay theoretical. A subcontractor's company-level accreditation does not tell you whether the individual electrician standing at your gate this morning holds a valid card, has completed your site induction, and understood the briefing on today's specific hazards.
Checking a card is a start. Our guide to checking a CSCS card is valid covers how, but a card only proves a generic test was passed at some point in the past. It does not prove site-specific induction or understanding, and it says nothing about the second and third-tier subcontractors your Tier 1 or Tier 2 subcontractor has brought with them, the layer most principal contractors cannot see at all.
Multi-tier subcontracting is where most competence risk actually sits. If your visibility stops at the subcontractor you have a direct contract with, you are managing the tier you can see and hoping the rest holds up.
Ongoing management means monitoring quality and programme against the subcontract, running the coordination and cooperation that Regulation 13 requires, planning meetings between contractors working on the same site at different stages, and keeping records of what was agreed and briefed. It also means paying on the terms you set, promptly and without informal deductions, because payment behaviour is one of the biggest drivers of which subcontractors will prioritise your sites over a competitor's.
Where Subcontractor Management Breaks Down
Done at tender and never refreshed. An SSIP certificate can lapse or an insurance policy can expire eighteen months into a framework agreement, and nobody notices until an audit asks for current evidence.
The PQQ said the subcontractor's workforce is trained. Nobody verifies that at the gate, and nobody checks whether the second-tier labour the subcontractor brought in was ever covered by that assessment.
Planning meetings take place, RAMS get talked through, but there is no dated record that a specific person attended a specific briefing and confirmed they understood it.
When a client, an auditor or the Building Safety Regulator asks for evidence of subcontractor competence, the answer takes days to assemble instead of being a live status.
A Practical Subcontractor Management Routine
- Prequalify before tender and refresh it annually. Check SSIP or CAS status directly rather than filing the certificate the subcontractor sent you two years ago.
- Put competence, training and insurance requirements in the subcontract itself, not only in the PQQ. What is not in the contract is not enforceable.
- Verify credentials and inductions at mobilisation, for every worker the subcontractor sends, not just the names on their tender submission.
- Extend visibility past the first tier. Ask who your subcontractor's subcontractors are, and hold the same standard for them.
- Record cooperation, not just intent. Planning meetings, RAMS briefings and attendance should leave a dated record, not a memory.
- Track status by site, not by project. A subcontractor's workforce cleared for one site is not automatically cleared for another with different hazards.
- Keep the audit pack current, not retrospective. If evidence takes more than a few minutes to produce, it is not an audit trail, it is a filing exercise.
Common Questions
What is subcontractor management in construction?
Subcontractor management is the process a principal contractor uses to select, contract, monitor and prove the competence of the subcontractors working on its sites. It covers prequalification, contract terms, on-site competence checks and ongoing performance and payment management, and it extends down through every tier of the supply chain, not just the contractors you appoint directly.
Who is responsible for subcontractor safety on a construction site?
Under CDM 2015, the principal contractor is responsible for planning, managing, monitoring and coordinating health and safety during the construction phase, including checking that every contractor appointed, at every tier, has the necessary skills, knowledge and experience. The Building Safety Act 2022 reinforces this by requiring principal contractors to take all reasonable steps to ensure subcontractor competence across the whole supply chain.
What should a subcontractor management plan include?
A subcontractor management plan should cover prequalification criteria and refresh dates, contractual requirements for competence and insurance, the process for verifying credentials and inductions on site, how coordination and cooperation are recorded, and how performance and payment are tracked against the contract. The plan is only useful if it produces evidence you can retrieve quickly, not just a process you can describe.
What is the difference between CHAS and Constructionline?
Both are SSIP member schemes and both are widely used for prequalification, but they work slightly differently. CHAS assesses health and safety policy, competence and management of subcontractors directly. Constructionline operates more as a national register, validating members against the Common Assessment Standard and PAS 91 criteria on behalf of buyers. Because both are SSIP members, health and safety approval from one is generally recognised by the other rather than reassessed from scratch.
How do you manage multiple tiers of subcontractors?
Start by requiring your direct subcontractors to disclose who they intend to subcontract to, and apply the same prequalification and competence standard down the chain rather than stopping at the first tier. Visibility is the main failure point: most principal contractors can evidence competence for the subcontractor they have a direct contract with, but not for the workers that subcontractor brings in beneath them.
What does the Building Safety Act require of principal contractors regarding subcontractors?
The Building Safety Act 2022 requires principal contractors to take all reasonable steps to ensure that every subcontractor and supply chain member, across every tier, meets building safety competence requirements. It applies to construction work generally, not only higher-risk buildings, and it widens the definition of competence beyond skills, knowledge and experience to include behaviour.
Is retention still allowed on subcontracts?
Yes, for now. Retention, typically 3 to 5 percent of contract value withheld until defects are resolved, remains standard practice. The government introduced the Commercial Payments Bill in May 2026, which includes provisions to ban retention deductions in construction contracts, but this has not yet passed into law. Confirm the current position before relying on it in a live contract.
Subcontractors Are Not the Risk. Invisible Ones Are.
Prequalification tells you a subcontractor is competent in principle. It does not tell you who they sent to your site this morning, whether that person was inducted, or whether the tier beneath them was ever checked at all. LUMA1 holds competence, induction and attestation evidence against every worker, on every site, across every tier of your supply chain, so the status is one word and the evidence is one link.