Construction compliance guide
Managing Subcontractors in Construction: A Builder's Guide
TL;DR
As the main builder, check a subcontractor can do the work safely before you appoint them, and agree the job in writing. Before they start, accept their RAMS, induct their workers and check their cards. On site, supervise, check and coordinate the work. At the end, collect what the health and safety file needs. Keep one record per subcontractor, with every expiry date.
This guide is for the main builder: the firm that brings in subcontractors and runs the site. It follows a subcontractor from choosing them to the end of their work, in five stages. If you are the subcontractor, see what documents subcontractors need for site instead.
It covers Great Britain under the Construction (Design and Management) Regulations 2015 (CDM 2015). Northern Ireland has its own CDM 2016 Regulations; see HSENI's CDM 2016 guidance.
Where there is, or will be, more than one contractor on a project, the client must appoint a principal contractor in writing (regulation 5). If you run the site and bring in subcontractors, that is usually you. Not sure? Use our free CDM role finder.
Managing subcontractors on every job? See how Business keeps the record
Business adds team logins, a record of the subcontractor paperwork you have checked, inspections and site files around each job, so the office and site team work from one record.
Request a Business walkthrough →Just need the paperwork for one job? Start free
In this guide
1. Choosing a subcontractor
Before you appoint a subcontractor, you must take reasonable steps to check that they have the skills, knowledge and experience, and, if they are a firm, the organisational capability, to do the work safely (regulation 8).
HSE says what is reasonable depends on how complex the job is and the risks involved (L153, paragraph 58). Keep your questions sensible and proportionate: ask for what tells you about the risks of the job and the firm's capability, and avoid excessive or duplicated paperwork (paragraph 60).
Ask for:
- Pre-qualification answers. Our free subcontractor pre-qualification questionnaire is a form they fill in and send back to you.
- Accreditation, such as an SSIP member scheme, with its expiry date. HSE says the law does not require it, and that a scheme assessment is not proof that a firm can manage the risks of the work on site (HSE). See our SSIP accreditation guide.
- Insurance certificates: employers' liability if they employ anyone, and the public liability and other cover your contract asks for. See checking a subcontractor's insurance.
- An example of their RAMS for similar work, so you can see how they plan.
- References from recent jobs. HSE says to check that a firm has enough experience and a good record in managing the risks involved, ideally after the pre-qualification checks and before you appoint (L153, paragraph 61).
If you are a CIS contractor, you also need to verify a new subcontractor with HMRC before you pay them (HMRC). That is a tax check, not a safety one.
2. Appointing them
Agree the job in writing before they start:
- The scope: what they will do, where it starts and ends, and what they will not do.
- Who supplies what: access equipment, scaffold, plant, power, welfare and waste.
- Who supervises their workers day to day, and how to reach them.
- When their RAMS are due, and who on your side reviews them.
- The site rules, and the parts of the construction phase plan that apply to their work.
Where there is more than one contractor, each contractor must follow the principal contractor's directions and the parts of the construction phase plan that apply to their work (regulation 15(3)).
Information you give them must be easy to understand and given as soon as is practicable, and everyone with a duty under CDM 2015 must cooperate with the others on the project as far as each needs to carry out their duties (regulation 8(4) and (6)).
3. Before they start
- Review and accept their RAMS. Check them against the job, the site, the other trades and the construction phase plan. Our guide to reviewing subcontractor RAMS takes you through it step by step.
- Induct their workers. Where there is more than one contractor, the principal contractor must make sure a suitable site induction is provided (regulation 13(4)). HSE says it should be specific to the site and cover the risks and controls people need to know (L153, paragraph 133).
- Check their cards and certificates. A contractor must not appoint anyone to work on site who does not have, or is not getting, the skills, knowledge, training and experience for their tasks (regulation 15(7)). Check CSCS cards with CSCS Smart Check: CSCS says looking at a card will not show that it is fake or has been revoked (CSCS). See our CSCS Smart Check guide.
- Note every expiry date: insurance, accreditation, cards and certificates, so you can see what runs out next.
- Brief them on the emergency arrangements: who to call, the nearest A&E and the assembly point. Our free emergency plan template has a section for each.
Managing subcontractors on every job? See how Business keeps the record
Business adds team logins, a record of the subcontractor paperwork you have checked, inspections and site files around each job, so the office and site team work from one record.
Request a Business walkthrough →Just need the paperwork for one job? Start free
4. On site
Every contractor must give the workers it controls appropriate supervision, instructions and information (regulation 15(8)). HSE says principal contractors do not have to supervise contractors' work in detail (L153, paragraph 128). Where there is more than one contractor, the principal contractor must still plan, manage, monitor and coordinate the construction phase (regulation 13(1)).
- Know who is on site each day. A sign-in record also helps with the roll call in an emergency.
- Brief people as the work changes, for example with a short toolbox talk.
- Check the supervision happens. Agree who supervises their workers, and check that they do. Our guide to site manager duties sets out what your own site manager does each day and week.
- Check the work regularly. HSE suggests routine checks of site access, work areas and plant and equipment, and prompt action when something is wrong (L153, paragraph 129). Write down what you find and who will put it right; see our site inspection record guide.
- Stop unsafe work. Anyone working under someone else's control must report anything likely to put themselves or others in danger (regulation 8(5)), and HSE says the person in control should encourage workers to stop work and report dangerous conditions (L153, paragraph 68). Agree a safe way forward before the work starts again.
- Coordinate the trades. Where there is more than one contractor, the principal contractor must organise cooperation between contractors, including those who follow each other on the same site (regulation 13(3)). HSE suggests regular planning meetings (L153, paragraph 130).
- Keep the record up to date. Check documents again before they expire, and update the record when new workers arrive or the RAMS change.
5. When their work finishes
On a project with more than one contractor, there must be a health and safety file, and the principal contractor must give the principal designer any information it holds that is relevant to the file (regulation 12(7); L153, Appendix 4).
Your subcontractors often hold that information: what they installed, hazardous materials used, where services run, and as-built details. HSE warns it may be difficult to get after they have left the project (L153, Appendix 4), so ask for it before their last day.
Then write a short note on how they did: the quality of the work, how safely they worked, and whether their paperwork came on time. It will help the next time you choose a subcontractor.
Free subcontractor record sheet
Keep one row per subcontractor. The sheet has two tables that share a reference number.
Choosing and appointing
- Company and trade
- Scope agreed in writing (date)
- Pre-qualification answers checked (date, by)
- Accreditation (scheme, expiry)
- Employers' liability (expiry)
- Public liability (expiry)
Before they start, on site and at the finish
- RAMS accepted (revision, date, by)
- Workers inducted (date)
- Cards and certificates checked (date, by)
- Next expiry to watch
- Health and safety file information received (date)
- How they performed
Download a blank subcontractor record sheet template
Free, no sign-up. Print the PDF and fill it in by hand, or fill in the Word file on a computer.
Get the free subcontractor pre-qualification questionnaire →
Keeping the record in The Site Book
On Pro and above, add each firm under Subcontractors in the sidebar with its insurance, RAMS and liability documents and their expiry dates. Then link it to the job on the project's Subcontractors tab.
On Business, each firm on a project also has a Business evidence review. Record the RAMS, insurance, training or certificate you checked, with its expiry date and your note on what you checked and the result, then mark it Record approved or Record rejected. The project's audit pack lists each subcontractor on the job, whether their documents are on file and in date, and the evidence records you added.
Business also gives you up to 10 team logins, Site Supervisor logins for whoever runs each site, inspections with corrective actions, and named approvals with review history on your own documents.
It is your own record. The Site Book does not contact your subcontractors or ask them to upload anything.
Related on The Site Book
Toolbox talks
Compare tools
Common questions
Who is responsible for a subcontractor's health and safety?
Both of you. Every contractor must plan, manage and monitor its own work and the workers under its control (CDM 2015, regulation 15(2)). Where there is more than one contractor, the principal contractor must also plan, manage, monitor and coordinate the whole construction phase (regulation 13(1)). Bringing in a subcontractor does not take your own duties away.
Do subcontractors need SSIP accreditation?
No. HSE says the law does not require it and that it is only one way of meeting prequalification standards. You can ask for it, or ask the same questions yourself with a pre-qualification questionnaire. HSE also says a scheme assessment is not proof that a firm can manage the risks of the work on site, so check the job itself as well.
What insurance should I ask a subcontractor for?
Employers' liability if they employ anyone: most employers must hold it, with cover of at least £5 million. Public liability is not required by law, so set the amount you need in the subcontract. Ask for contractor's all-risk where the contract needs it. Check the names, the cover and the expiry dates, and keep a copy.
Do I need to check a subcontractor for CIS?
If you are a CIS contractor, yes. Before you pay a new subcontractor, you need to verify them with HMRC, which tells you whether they are registered and what rate of deduction to use. It is a tax check, not a health and safety check.
How often should I re-check a subcontractor's documents?
Before they start, before anything expires, and whenever the job, the people or the RAMS change. Write every expiry date in your record so you can see what runs out next.
What a subcontractor record does, and does not do
Pros
- Shows what you checked for each firm, when, and what you decided.
- Puts every insurance, accreditation and card expiry date in one place.
- Gives the site team the same picture of each firm as the office.
Cons
- A record is not supervision: you still need to check the work on site.
- An in-date certificate does not prove a firm can manage the risks of this job.
- It is only as current as the last time someone updated it.
| Stage | What you do | What you record |
|---|---|---|
| 1. Choose | Ask for pre-qualification answers, accreditation, insurance, an example of their RAMS and references. | What you checked, the expiry dates and your decision. |
| 2. Appoint | Agree the scope, who supplies what, and who reviews their RAMS, in writing. | The scope and the date you agreed it. |
| 3. Before they start | Accept their RAMS, induct their workers and check their cards. | The RAMS revision, the inductions and the card checks. |
| 4. On site | Brief, supervise, check and coordinate the work, and stop unsafe work. | Briefings, inspections, actions and changes. |
| 5. Finish | Collect information for the health and safety file and note how they performed. | What you received, and a short note on how they did. |
“Only enquiries for information that will address the anticipated risks and capability of the supplier should be made – excessive or duplicated paperwork should be avoided because it can distract attention from the practical management of risks.”
Related guides
- What documents do subcontractors need for site? (for the subcontractor)
- How to review subcontractor RAMS before work starts
- Principal contractor duties under CDM 2015
- What insurance do builders need?
- SSIP accreditation for small builders
- Free subcontractor pre-qualification questionnaire
- Business plan for growing construction teams
One record for every subcontractor on the job.
See how Business keeps each firm's checked paperwork and your review notes with the job, alongside team logins and inspections.
Sources
- The Construction (Design and Management) Regulations 2015, regulation 8 — legislation.gov.uk · Accessed 5 November 2026
- The Construction (Design and Management) Regulations 2015, regulation 12 — legislation.gov.uk · Accessed 5 November 2026
- The Construction (Design and Management) Regulations 2015, regulation 13 — legislation.gov.uk · Accessed 5 November 2026
- The Construction (Design and Management) Regulations 2015, regulation 15 — legislation.gov.uk · Accessed 5 November 2026
- Managing health and safety in construction (L153) — HSE · Accessed 5 November 2026
- Principal contractors: roles and responsibilities — HSE · Accessed 5 November 2026
- Contractors: roles and responsibilities — HSE · Accessed 5 November 2026
- Health and safety conformity assessment schemes — HSE · Accessed 5 November 2026
- The Employers' Liability (Compulsory Insurance) Regulations 1998, regulation 3 — legislation.gov.uk · Accessed 5 November 2026
- Employers' Liability (Compulsory Insurance) Act 1969: a brief guide for employers (HSE40) — HSE · Accessed 5 November 2026
- What you must do as a CIS contractor: verify subcontractors — HMRC (GOV.UK) · Accessed 5 November 2026
- How can I check a CSCS card? — CSCS · Accessed 5 November 2026
This guide is general guidance, not legal advice. Check the law and HSE's guidance for your own jobs.