Contractor Onboarding Checklist for Large Clients (UK)

Introduction

If you’re a contractor trying to win (and keep) work with large clients, onboarding can feel like a project in its own right. Bigger organisations typically have stricter procurement rules, deeper health and safety requirements, and more detailed insurance and compliance checks. Miss one document or fail to evidence a process and you can lose weeks—or the contract.

This guide gives you a clear, step-by-step contractor onboarding checklist designed for UK businesses working with large clients (manufacturing, construction, facilities, engineering, logistics, and professional services). It covers what large clients usually ask for, why they ask, and how to prepare so you look organised, compliant, and low-risk.

Why large clients have tougher onboarding

Large clients are managing risk at scale. Their onboarding process is designed to reduce:

• Operational risk (delays, quality issues, supply chain disruption)

• Health & safety risk (accidents, enforcement action, reputational damage)

• Legal and contractual risk (disputes, unclear scope, IP ownership)

• Financial risk (insolvency, cashflow issues, fraud)

• Regulatory risk (GDPR, employment status, industry standards)

If you can make their risk team confident, you become easier to approve—and easier to reappoint.

Before you start: build your onboarding pack

Create a single “Contractor Onboarding Pack” folder (cloud-based) so you can share documents quickly. Keep a version-controlled master set and a client-specific copy.

Your pack should include:

• Company profile and capability statement

• Key contacts and escalation list

• Insurance certificates and schedule of cover

• H&S policy, RAMS templates, training matrix

• Quality management documents (where relevant)

• Cyber and data protection documents

• Standard terms, contract templates (if used)

• Evidence of accreditations and memberships

• Banking details and VAT information

Tip: Large clients love clear file names. Use a consistent format like: CompanyName_DocumentName_YYYY-MM-DD.

Contractor onboarding checklist (large client ready)

1) Pre-qualification and due diligence

Large clients often start with a pre-qualification questionnaire (PQQ) or supplier onboarding form.

Checklist:

• Confirm legal entity name, company number, registered address

• VAT registration number (if applicable)

• UTR (where requested)

• Business bank details (with proof)

• Ownership structure and key directors

• Trading history and references

• Financial information (accounts, management accounts, or credit checks)

• Modern Slavery Act statement (if applicable or requested)

• Anti-bribery and corruption policy

• Sanctions/AML checks (especially for international supply chains)

What to prepare:

• A short “About us” statement (50–150 words)

• A one-page capability statement (services, sectors, geographic coverage)

• Two to three client references with contact permission

2) Scope clarity and onboarding call

Before paperwork spirals, lock the basics.

Checklist:

• Confirm scope of work and deliverables

• Confirm site locations and access requirements

• Confirm working hours, shift patterns, and supervision

• Confirm who provides equipment, materials, and PPE

• Confirm reporting lines and day-to-day contacts

• Confirm KPIs, SLAs, and quality expectations

• Confirm start date, mobilisation timeline, and dependencies

Best practice: Write a short scope summary email after the call. It reduces disputes and speeds contract review.

3) Contracting and legal documents

Large clients will usually issue their own contract or framework agreement.

Checklist:

• Review contract type: MSA, framework, call-off, PO terms

• Confirm payment terms (30/60/90 days) and invoicing rules

• Confirm liability caps, indemnities, and exclusions

• Confirm IP ownership and confidentiality obligations

• Confirm subcontracting rules and approval process

• Confirm termination rights and notice periods

• Confirm dispute resolution and governing law (UK)

• Confirm “flow-down” obligations from the client’s customers

Documents you may be asked for:

• Signed contract / countersigned terms

• NDA (non-disclosure agreement)

• Data processing agreement (DPA) if you handle personal data

• Evidence of right-to-work checks (if labour is supplied)

If anything is unclear, ask targeted questions. Large clients respect contractors who spot risk early.

4) Insurance requirements (the big one)

Insurance is one of the fastest ways to fail onboarding if your cover doesn’t match the client’s minimum requirements.

Common covers large clients request:

• Public Liability (PL): often £2m–£10m

• Employers’ Liability (EL): typically £10m (legal minimum is £5m)

• Professional Indemnity (PI): for design, advice, consultancy, specification, or professional services

• Contractors’ All Risks (CAR): for construction works and materials on site

• Tools/plant/equipment cover: owned or hired-in plant

• Product Liability: if you supply products/components

• Cyber insurance: if you access systems or handle data

Checklist:

• Provide certificates and policy schedules (not just certificates)

• Ensure the business description on the policy matches your actual work

• Check any height/depth/heat work exclusions if you’re in construction

• Confirm territorial limits (UK / worldwide) match the contract

• Confirm policy dates cover the full project period

• Confirm any required endorsements (e.g., “principal’s indemnity”, “waiver of subrogation”)

• Confirm subcontractors are covered (or evidence their cover)

Pro tip: If the client asks for “indemnity to principal” wording, don’t guess—get your broker to confirm the correct endorsement.

5) Health & Safety (H&S) and site compliance

For large clients, H&S is often the most detailed part of onboarding—especially for site-based work.

Checklist:

• H&S policy (signed and dated)

• Risk assessment and method statement (RAMS) for each task

• COSHH assessments (chemicals, solvents, cleaning agents)

• PPE policy and issue records

• Accident/incident reporting procedure (RIDDOR awareness)

• First aid arrangements and trained first aiders

• Fire safety arrangements and evacuation procedures

• Plant and equipment inspection records (PUWER)

• Lifting operations plan (LOLER) if relevant

• Working at height plan and rescue plan if relevant

• Electrical safety (PAT, fixed wiring where applicable)

• Site induction completion records

• Toolbox talk records

• Competence and training matrix (CSCS, IPAF, PASMA, SSSTS/SMSTS, etc.)

What large clients look for:

• Evidence that RAMS are specific (not generic templates)

• Named competent persons and supervisors

• Clear control measures and sign-off

• A culture of reporting near misses

6) Workforce checks and employment status

If you supply labour, expect deeper scrutiny.

Checklist:

• Right to work checks (and retention process)

• Identity verification process

• DBS checks (if working in sensitive environments)

• IR35 status considerations (for certain engagements)

• Agency worker compliance (if you use agencies)

• Subcontractor vetting process

• Proof of qualifications and licences

Keep a secure, GDPR-compliant process for storing IDs and checks.

7) Data protection and cyber security

Even “non-IT” contractors can be asked about cyber controls if you handle personal data, access client systems, or use shared portals.

Checklist:

• GDPR privacy notice (if you collect personal data)

• Data protection policy and training evidence

• Data retention and deletion policy

• Incident response plan (data breach process)

• MFA (multi-factor authentication) enabled on key accounts

• Device security: encryption, patching, antivirus

• Secure file sharing process (avoid personal emails/USBs)

• Supplier risk management (your own vendors)

If you’ll access client systems, ask what security standards they require (e.g., Cyber Essentials).

8) Quality management and operational controls

For manufacturing, engineering, and technical services, quality documentation can be decisive.

Checklist:

• Quality policy and procedures

• Inspection and test plans (ITPs) where relevant

• Calibration records for measuring equipment

• Non-conformance reporting process

• Change control process

• Document control and versioning

• Traceability records (materials/components)

If you hold ISO accreditations (e.g., ISO 9001), provide certificates and scope.

9) Environmental and sustainability requirements

Many large clients now include ESG requirements in onboarding.

Checklist:

• Environmental policy

• Waste management and disposal process

• Spill response procedure (if applicable)

• Evidence of compliant waste carriers (if you transport waste)

• Carbon reduction plan (if requested)

• Sustainable procurement statement

Even a simple, honest policy is better than none.

10) Site access, permits, and mobilisation

Large clients often require formal permits and access controls.

Checklist:

• Site access request forms for each worker

• Proof of ID for passes

• Vehicle details for parking permits

• Permit-to-work requirements (hot works, confined space, electrical isolation)

• Induction booking and completion

• Welfare arrangements confirmed

• Emergency contacts and escalation routes

Build a mobilisation timeline with owners and deadlines so nothing slips.

11) Invoicing, onboarding to portals, and admin

Admin issues can delay payment more than the work itself.

Checklist:

• Confirm PO process (no PO, no pay)

• Confirm invoice format and required references

• Confirm timesheet approval process

• Confirm retention rules (construction contracts)

• Confirm CIS requirements (if applicable)

• Register on supplier portal (Ariba, Coupa, etc.)

• Set up remittance advice contact

Create an internal “invoice checklist” to prevent rejections.

12) Ongoing monitoring and compliance

Onboarding isn’t a one-off. Large clients often require ongoing evidence.

Checklist:

• Diary reminders for insurance renewals and updated certificates

• Regular RAMS reviews (especially if scope changes)

• Quarterly H&S stats (accidents, near misses, training)

• Subcontractor insurance and competence checks

• Annual policy reviews (H&S, data protection, anti-bribery)

• Lessons learned and continuous improvement notes

If you can proactively send updates, you’ll stand out as “easy to manage.”

A simple contractor onboarding timeline (example)

Here’s a practical way to plan onboarding without chaos:

• Day 1–2: Confirm scope, key contacts, mobilisation plan

• Day 3–5: Submit PQQ/supplier forms, company docs, insurance pack

• Week 2: Submit RAMS, training matrix, site induction bookings

• Week 3: Contract finalised, portal setup, PO process confirmed

• Go-live: Site access approved, permits ready, supervisor briefed

Common onboarding mistakes (and how to avoid them)

• Sending generic RAMS: Tailor to the site, task, and client rules.

• Wrong insurance description: Make sure your policy reflects what you actually do.

• Missing subcontractor evidence: Vet and document your supply chain.

• Ignoring portal requirements: Learn the client’s invoicing rules early.

• No single owner internally: Assign one onboarding lead to chase actions.

How insurance fits into contractor onboarding

Large clients want reassurance that if something goes wrong, there is financial protection in place. The right insurance can also help you win work by reducing perceived risk.

At a minimum, most contractors need Public Liability and Employers’ Liability. If you provide advice, design, specification, or professional services, Professional Indemnity is often essential. If you’re doing contract works, Contractors’ All Risks may be required. Cyber is increasingly requested when data and systems are involved.

If you’re unsure what your client will ask for, start by requesting their insurance schedule and contract requirements early—then align your cover before you submit documents.

FAQs

What documents do large clients usually ask contractors for?

Typically: company details, insurance certificates/schedules, H&S policy, RAMS, training records, accreditations, financial info, and data protection documents.

How much Public Liability insurance do large clients require?

It varies, but £2m to £10m is common. Higher-risk work (construction, high footfall sites) often sits at the upper end.

Do I need Professional Indemnity insurance as a contractor?

If you provide advice, design, calculations, specifications, project management, or any service where a client could claim financial loss from your work, PI is commonly required.

What is RAMS and why is it important?

RAMS stands for Risk Assessments and Method Statements. Large clients use RAMS to confirm you’ve identified hazards and have control measures in place.

How can I speed up contractor onboarding?

Prepare a standard onboarding pack, keep documents current, tailor RAMS, and assign one internal owner to manage deadlines and client queries.

What if a client’s insurance requirements are higher than my current cover?

Speak to your broker early. In many cases, limits can be increased or endorsements added, but it’s better to do this before you submit onboarding documents.

Conclusion

Large client onboarding is less about paperwork for paperwork’s sake and more about proving you’re a safe, reliable, and low-risk supplier. If you build a repeatable onboarding pack, tailor your H&S documents, and align your insurance to client requirements, you’ll move through approvals faster and protect your business at the same time.

If you’d like, tell me what type of contracting you do (construction, engineering, facilities, professional services, marine/offshore, etc.) and the typical client size, and I can tailor this checklist to your niche and the insurance limits large clients in that sector commonly request.