Borrowed Workers, Owned Liability: How Labour Supply Arrangements Are Quietly Transferring Safety Responsibility to Host Businesses

The language of modern workforce arrangements is rich with implied distance. Workers are 'supplied', 'placed', 'deployed', or 'provided'. Staffing agencies are 'the employer'. Host businesses are 'the client'. Contracts are drafted to delineate responsibilities with apparent precision, allocating obligations between parties and creating, on paper at least, a clear picture of who is accountable for what.

Under UK workplace safety law, much of that picture dissolves the moment a worker sets foot on a host site. The legal reality of labour supply arrangements — agency staff, zero-hours workers, labour-only subcontractors, and the various hybrid arrangements that populate modern supply chains — is considerably less comfortable for host businesses than their contracts suggest. And the gap between contractual expectation and legal obligation is where enforcement actions, prosecutions, and civil claims are increasingly found.

The Statutory Position: What UK Law Actually Says

The Health and Safety at Work etc. Act 1974 imposes a duty on employers to ensure, so far as is reasonably practicable, the health, safety, and welfare of their employees. But it does not stop there. Section 3 of the same Act extends the duty to non-employees: employers must conduct their undertaking in a way that ensures, so far as is reasonably practicable, that persons not in their employment who may be affected by their activities are not exposed to risks to their health or safety.

For host businesses, this provision is significant. Agency workers, labour-only contractors, and zero-hours workers operating on a host's premises, using a host's equipment, and working under a host's supervision are persons who may be affected by that host's undertaking. The contractual label applied to the relationship — whether 'agency worker', 'self-employed contractor', or otherwise — does not determine the scope of the statutory duty.

The Management of Health and Safety at Work Regulations 1999 reinforce this position explicitly. Regulation 12 requires host employers to provide agency workers with comprehensible information about risks and control measures before they begin work. Regulation 16 imposes specific obligations in relation to new and expectant mothers. The regulations make no provision for these duties to be discharged by the supplying agency instead of the host — they sit with whoever controls the work environment.

The Staffing Agency's Role: Genuine but Limited

This is not to suggest that staffing agencies bear no safety obligations. Under the Conduct of Employment Agencies and Employment Businesses Regulations 2003, agencies are required to obtain information from clients about the nature of the work, the qualifications required, and any risks associated with the position. They are also required to provide workers with that information before placement.

However, the agency's ability to fulfil these obligations depends entirely on the information the host provides. An agency cannot assess the hazards of a site it has not visited, cannot verify that control measures described by a client are actually in place, and cannot induct a worker into safe practices for an environment it does not control. In practice, the agency's safety function is necessarily limited to the pre-placement stage.

Once a worker is on site, the host controls the physical environment, the equipment, the pace of work, the supervision arrangements, and the behavioural expectations. The host is, in every operationally meaningful sense, managing that worker's safety — regardless of what the staffing contract says about employer status.

Where Host Businesses Consistently Misjudge Their Exposure

The compliance failures most frequently identified by the HSE in labour supply contexts cluster around three areas.

Induction and site-specific training. Host businesses frequently assume that agency workers have received adequate safety training from their placing agency. In reality, generic training provided by an agency — covering broad topics such as manual handling awareness or fire safety principles — does not constitute site-specific induction. A worker who has completed online training modules about forklift awareness has not been inducted into the specific traffic management arrangements operating on a particular warehouse floor. The host's obligation to provide that site-specific information is not discharged by the agency's generic provision.

Supervision and competency verification. The contractual designation of a worker as 'self-employed' or 'supplied by an agency' does not reduce the host's obligation to verify that the worker is competent to perform the tasks assigned and is being appropriately supervised. HSE investigations following incidents involving agency workers frequently reveal that hosts made assumptions about competency based on the worker's placement by an agency, without independent verification. Courts have consistently declined to accept this as a reasonable approach.

Risk assessment coverage. Many host businesses conduct risk assessments that implicitly assume a stable, directly employed workforce. Agency workers, who may be less familiar with site-specific hazards, may have language barriers, and who may be rotated between sites, represent a distinct risk profile that generic assessments do not adequately address. The failure to account for the specific vulnerabilities of a transient or agency workforce in the assessment process has featured in numerous enforcement actions.

The Zero-Hours Complication

Zero-hours arrangements add a further layer of complexity. Workers engaged on zero-hours terms may not be consistently present on any given site, may work across multiple locations for the same or different engagers, and may have an irregular and fragmented relationship with the host's safety culture and procedures. Yet their legal status as workers — rather than self-employed contractors — means that the host's obligations under the Working Time Regulations 1998 and the Health and Safety at Work etc. Act apply in full.

The intermittent nature of zero-hours engagement creates particular challenges for induction and training record management. A worker who attended a site induction six months ago, has since worked elsewhere, and returns to the same host may be treated as already inducted — despite having had no meaningful engagement with site-specific safety information in the intervening period. Where an incident occurs in these circumstances, the host's induction records may be found to be materially misleading.

The HSE's Enforcement Direction

The Health and Safety Executive has made clear, through both published guidance and enforcement practice, that it does not regard contractual arrangements as determinative of safety responsibility. Its guidance on agency workers states explicitly that host employers must treat agency workers as they would their own employees with respect to health and safety.

Recent enforcement trends reflect this position. Prosecutions arising from incidents involving agency workers have increasingly targeted host businesses rather than, or in addition to, supplying agencies. Penalty levels in such cases have risen materially, and the HSE has demonstrated a willingness to pursue director-level accountability where management systems are found to have been inadequate.

A Framework for Identifying and Managing Hidden Obligations

For host businesses seeking to understand and manage their actual exposure, the following framework provides a practical starting point.

Workforce mapping. Identify every individual working on your premises or under your direction, regardless of their contractual status. This includes agency workers, zero-hours workers, labour-only subcontractors, and any other non-directly-employed persons. The resulting map forms the basis for an accurate assessment of your safety obligations.

Obligation audit. For each category of worker identified, assess what specific safety obligations apply under statute and regulation. Do not assume that contractual allocation of responsibility to an agency satisfies those obligations. Where statutory duties sit with the host, they must be discharged by the host.

Induction architecture. Develop an induction process that distinguishes between generic safety awareness (which an agency may legitimately provide) and site-specific induction (which only the host can provide). Ensure that every worker, regardless of status, completes site-specific induction before commencing work. Maintain records that demonstrate this.

Risk assessment review. Review existing risk assessments to ensure that the specific characteristics of non-directly-employed workers — including potential language barriers, unfamiliarity with site-specific practices, and irregular attendance — are explicitly addressed.

Contract review. Examine existing staffing contracts and agency agreements to identify provisions that purport to transfer safety obligations to the agency. Obtain legal advice on whether those provisions are enforceable and, where they are not, what steps are required to ensure the host's actual obligations are met.

The Liability That Contracts Cannot Transfer

The fundamental lesson of labour supply compliance is one that UK courts and the HSE have articulated repeatedly: statutory safety obligations cannot be contracted away. A business that controls a work environment, directs the activities performed within it, and benefits from the labour of those who work there is a business that bears safety responsibility for those workers — whatever its contracts say to the contrary.

The staffing industry's commercial model is legitimate and economically valuable. The compliance obligations it generates for host businesses are equally legitimate — and equally unavoidable. Recognising that reality, and building safety management systems that reflect it, is not merely good practice. Under UK law, it is a legal requirement.