How do you communicate with subcontractors about safety?

Subcontractors, agency workers and temporary staff often face the highest risks on your site. They are new to the location, they do not know your rules, and they are not on your systems. Yet they are expected to work safely from the first hour.

This guide explains how to communicate safety to subcontractors and flexible workers in the UK. It covers your legal duties, how to brief people before they arrive, how to run toolbox talks for people without a company account, and how to build one safety process for everyone who works for you.

Why subcontractors are harder to reach

Your own employees are on your payroll, in your HR system and in your team briefings. External and flexible workers are not.

• They arrive at short notice. A subcontractor crew or agency worker may be booked the day before.
• They are not on your systems. No company email, no intranet login, no app account.
• They change often. The crew on Monday may not be the crew on Thursday.
• They work for someone else. Their own employer briefs them on general risks, but not on the specific hazards of your site.
• Language varies. Many crews include workers whose first language is not English.

The result is a gap: everyone assumes someone else has passed on the information. Closing that gap is a legal duty as well as good practice.

Your legal duties in the UK

Toolbox talks are not themselves a named legal requirement, but several UK regulations require you to share information with people who are not your direct employees.

Health and Safety at Work etc. Act 1974

Section 3 of the Health and Safety at Work etc. Act 1974 requires you to conduct your undertaking so that people who are not your employees, including contractors, are not exposed to risks to their health and safety, so far as is reasonably practicable.

Management of Health and Safety at Work Regulations 1999

• Reg. 11: where employers share a workplace, they must co-operate and co-ordinate their safety measures and inform each other of the risks.
• Reg. 12: you must give the employers of people working in your undertaking, and those workers themselves, comprehensible information on the risks and the measures in place, including emergency procedures.
• Reg. 15: before a temporary or agency worker starts, you must give them information on any special qualifications or skills needed and any health surveillance required. Where they come through an agency, you give this to the agency, which must pass it on.

You can read the full text on legislation.gov.uk.

CDM 2015 on construction sites

On construction projects, the Construction (Design and Management) Regulations 2015 add specific duties.

• Principal contractor (reg. 13): plans, manages and co-ordinates the construction phase, ensures a suitable site induction is provided, and makes sure contractors and workers are consulted and informed.
• Contractors (reg. 15): must only appoint workers with the right skills, knowledge, training and experience, and must give each worker under their control appropriate supervision, instructions and information, including a suitable site induction where the principal contractor has not already provided one.

The HSE's CDM 2015 guidance explains these roles in more detail. Site inductions for visitors and contractors are a topic of their own: see what a site induction is.

Informing subcontractors before they start

The best moment to share site-specific rules is before people arrive. A briefing at the gate on the first morning is rushed, and people forget most of it by lunchtime.

What to share in advance

• Site address, access route, parking and where to report
• Site rules: PPE, speed limits, smoking, mobile phones, permits to work
• Specific hazards: live traffic, overhead lines, confined spaces, chemicals, work at height
• Emergency procedures: alarm, assembly point, first aid, how to report an accident or near miss
• Who to contact on site, by name and phone number
• Welfare facilities

How to get it to them

Send the information to each worker's phone a day or two before they start. Keep it short, add photos of the entrance, assembly point and key hazards, and finish with a few questions to check understanding. When people arrive, you already know who has completed it. An online site induction via WhatsApp does exactly this, without asking contractors to install anything.

Toolbox talks for people without a company account

Many digital training tools assume every user has a login. Subcontractors and agency staff usually do not, and creating accounts for a crew that is on site for two weeks is not realistic.

The simplest solution is to use the phone number as the key. A talk is sent to the worker's phone, they open it without logging in, answer a few questions, and the result is stored against their name and company. This works equally well for your own staff, so everyone gets the same talk in the same way.

For talks held in person, record attendance by having people scan a QR code with their phone camera instead of signing a paper sheet. Read more about registering who attended a physical toolbox talk.

Agency and temporary workers

Agency and temporary workers face a double gap: the agency does not know your site, and you do not know the worker. Make the split of responsibilities clear.

Party	What they cover
Agency (employment business)	General training, qualifications, right paperwork, passing on your information
You (the hirer)	Site-specific risks, rules, emergency procedures, task instructions, supervision
Both	Agreeing in writing who does what, and checking it happens

Practical steps that help:

1. Agree with the agency what information you send and when.
2. Send site-specific information directly to the worker's phone before the first shift.
3. Use short, visual content in the worker's own language.
4. Check understanding with a few questions, not a signature alone.
5. Give closer supervision during the first days.
6. Repeat key topics: temporary workers join throughout the year, so one induction day is not enough.

One safety process for permanent, flexible and subcontracted staff

Running separate processes for employees, agency staff and subcontractors creates gaps and admin. Where possible, use one process for everyone who works on your site.

• Same content: a hazard is the same hazard whoever employs the person facing it.
• Same channel: if your own staff get toolbox talks on their phone, so can a subcontractor crew.
• Same records: one overview of who completed what, filtered by company, site or role.
• Different routes in: permanent staff via your HR and planning systems, subcontractors via their own supervisor or a link they share with their crew.

This also makes audits easier. When a client or auditor asks whether everyone on site was briefed, you have one answer instead of three folders. See how to prevent failing a safety audit.

Keeping subcontractors informed during the job

Information does not stop after the induction. Site conditions change every week.

• Send a short toolbox talk to all crews when a new phase starts, such as scaffolding going up or a crane arriving.
• Share lessons from near misses with everyone on site, not only the company involved.
• Use daily pre-start briefings and a point of work risk assessment for high-risk tasks.
• Close the loop: tell people what was done with the hazards they reported.

Frequently asked questions

Who is responsible for briefing subcontractors on site rules?

Both parties have duties. As client or principal contractor you must share site-specific risks and rules, and the subcontractor must make sure their workers receive and follow that information. On construction projects, CDM 2015 places the site induction duty on the principal contractor and contractors.

Do agency workers need a separate induction?

They need the same site-specific information as your own staff before they start work. Under MHSWR reg. 15 you must also give information on required skills and health surveillance, via the agency if they come through one.

How do you deliver toolbox talks to people without access to your systems?

Use a channel that does not need an account, such as a talk sent to their phone via WhatsApp. The phone number identifies the worker, so there is no login, and their answers are recorded.

Can subcontractors complete the site induction before arriving?

Yes, and it is often better. People can read and watch it at a calm moment, you can check understanding with a few questions, and you know before the first shift who is ready to start.

How do you deal with subcontractor crews who speak different languages?

Provide the information in their own language and use photos and video. Check understanding with simple questions rather than relying on a signature.

How E-lia helps

E-lia sends site inductions, toolbox talks and safety updates to every worker's phone via WhatsApp, including subcontractors and agency staff. There is no app and no login. Each person receives the content in their own language, answers a short knowledge check, and the results appear in your dashboard per company, site and person. Physical talks can be registered with a QR code. You can use our ready-made toolbox talks or have your own material imported for you.