How to start and run a general contracting business in the UK

A general contracting business coordinates and delivers construction projects by managing trades, materials, programme and compliance on behalf of a client. Your immediate next step is to choose a legal structure, register with Companies House and HMRC, confirm your CDM role responsibilities, and secure insurance before you take on a single contract.

Your first 72-hour checklist:

• Choose your legal structure (limited company or sole trader) and register at Companies House or notify HMRC of self-employment
• Register with HMRC for Self Assessment, PAYE or CIS as your situation requires
• Identify whether you will act as principal contractor under CDM 2015 and read the HSE principal contractor guidance
• Arrange public liability and employers' liability insurance before any site activity
• Open a dedicated business bank account
• Download and read HMRC's CIS 340 guidance if you will pay subcontractors

Key takeaways

Starting a general contracting business in the UK requires the right legal structure, CDM competence, insurance, and a standard job workflow before you take on your first contract.

Table of Contents

• What does a general contracting business actually do in the UK?
• How do you legally set up a general contracting business in the UK?
• What licences and qualifications do UK contractors actually need?
• What are your CDM 2015 duties as a principal contractor?
• What insurance does a contracting business need?
• How do contracts and payment terms protect your business?
• How do you estimate jobs, set mark-ups and manage subcontractors?
• How do PAYE, CIS and auto-enrolment work for contractors?
• What does it cost to start a contracting business, and when will you turn a profit?
• How do you find work and win bids as a new contractor?
• An operational checklist to run site, office and finance
• What I have learned building a contracting business from scratch
• Sources

What does a general contracting business actually do in the UK?

The term "general contractor" is widely used, but in UK construction the recognised industry terms are main contractor and, under health and safety law, principal contractor. Understanding the distinction matters before you price a single job.

A main contractor takes overall responsibility for delivering a construction project: coordinating subcontractors, managing the programme, procuring materials, and reporting to the client. The scope can range from a residential refurbishment or loft conversion to a commercial fit-out, a small new-build, or a multi-phase infrastructure package. The general contractor role is fundamentally one of coordination rather than direct trade execution, though many UK contractors also self-deliver some trades.

Principal contractor is a specific legal designation under the Construction (Design and Management) Regulations 2015 (CDM 2015). It applies when a project has more than one contractor working at any time. The principal contractor takes on statutory duties: preparing the construction phase plan, coordinating health and safety across the site, and liaising with the principal designer. You can be both main contractor and principal contractor on the same project, and on domestic client projects, the contractor often inherits client duties by default if no principal contractor is formally appointed.

Here is a quick-reference glossary of the terms you will encounter:

For a deeper look at the role of a main contractor in UK construction, including how responsibilities shift across project stages, that guide covers the full picture.

How do you legally set up a general contracting business in the UK?

Most new contracting businesses incorporate as a limited company rather than operating as sole traders. The primary reason is liability: a limited company separates your personal assets from business debts, which matters enormously when you are holding subcontractor contracts, retentions and site insurance obligations simultaneously. Sole trader status is simpler to set up and cheaper to administer, but it leaves personal assets exposed and can limit your ability to tender for commercial work where clients require a registered company.

A partnership sits between the two: straightforward to establish but with shared unlimited liability unless you form a Limited Liability Partnership (LLP).

Registering a limited company

Incorporation at Companies House takes as little as 24 hours online and costs £50 for the standard digital route. You will need a company name, a registered office address in the UK, at least one director, and details of shareholders. Once incorporated, Companies House issues a certificate of incorporation and assigns a company number. From that point, you must file a confirmation statement annually and submit accounts within the required deadlines.

Companies House filing history is publicly searchable, so clients and principal designers can verify your company's formation date, director history, and filed accounts at any time. This is worth knowing: your filing history is part of your credibility record, not just a compliance obligation.

Registering with HMRC

Once incorporated, register the company with HMRC for Corporation Tax within three months of starting to trade. If you will employ staff, register as an employer for PAYE before the first payroll run. If you will pay subcontractors under the Construction Industry Scheme, register as a CIS contractor separately. These are distinct registrations and missing one creates compliance gaps from day one.

For sole traders, notify HMRC of self-employment by 5 October following the end of the tax year in which you started trading, and register for Self Assessment.

VAT registration becomes mandatory once your taxable turnover exceeds £90,000 in any rolling 12-month period. Many contractors register voluntarily before that threshold to reclaim VAT on materials and plant, particularly if their clients are VAT-registered businesses.

Practical note: Open a business bank account before your first invoice. Mixing personal and business funds creates accounting problems and looks unprofessional to clients who request bank details for payment runs.

What licences and qualifications do UK contractors actually need?

There is no single national "general contractor licence" in the UK. That is the most common misconception among people researching how to start a contracting business. What you need instead is a combination of trade-specific qualifications, demonstrable competence for CDM roles, and scheme memberships that clients and insurers will ask for.

The Building Act 1966 does restrict certain building work to licensed or authorised parties, but the day-to-day competence framework for most UK contractors is built around the following:

• CSCS card (Construction Skills Certification Scheme): The industry-standard site access credential. Most principal contractors and clients require all site operatives to hold a valid CSCS card appropriate to their role and qualification level. As the business owner, you will typically hold a manager-level card.
• Trade NVQs and City & Guilds qualifications: Relevant to the trades you self-deliver. An NVQ Level 3 in a specific trade (carpentry, brickwork, plastering) underpins both CSCS card eligibility and CDM competence evidence.
• Gas Safe registration: Legally required for any business carrying out gas work. You cannot subcontract gas work to an unregistered operative and remain compliant.
• Electrical competence schemes: NICEIC, NAPIT or equivalent registration is required for notifiable electrical work. Without it, work must be inspected and certified by a registered body.
• CITB levy and training: The Construction Industry Training Board levies most construction employers. Registering with CITB also gives access to grants for training, which can offset the cost of NVQs and site safety courses for your workforce.
• Federation of Master Builders (FMB): Membership requires a vetting process and provides a quality signal to residential clients. NHBC registration is relevant if you are building or developing new homes and want to offer structural warranties.

For CDM appointments, CDM 2015 requires that contractors have the necessary skills, knowledge, experience and organisational capability for their role. That means you need to be able to demonstrate, not just assert, competence.

Pro Tip: Before tendering for a project where you will act as principal contractor, prepare a one-page competence summary: CSCS card numbers, relevant qualifications, previous project examples, insurance certificates, and your CDM management approach. Clients and principal designers will ask for this, and having it ready signals professionalism before the contract is signed.

What are your CDM 2015 duties as a principal contractor?

If your project involves more than one contractor working simultaneously, you will almost certainly act as principal contractor under CDM 2015. That triggers a specific set of statutory duties that go well beyond general site safety.

HSE requires the principal contractor to prepare a written construction phase plan before the construction phase begins, and to maintain arrangements for managing health and safety throughout the project. The plan is not a one-time document. It must be reviewed and updated as the project changes.

What the construction phase plan must contain

• Project description, site address and key duty holders
• Management structure and responsibilities for health and safety
• Communication and cooperation arrangements between contractors
• Site rules, induction procedures and welfare arrangements
• Arrangements for managing significant site risks (working at height, excavations, services)
• Emergency procedures and first aid arrangements
• Programme of works with key health and safety milestones
• Arrangements for monitoring and reviewing the plan

Turning that plan into a live document means distributing it to every appointed contractor before they start work, version-controlling every revision, recording that operatives have received site inductions, and keeping a log of toolbox talks. An inspector visiting site will ask to see the plan, the induction records, and evidence that subcontractors have received the relevant sections.

The HSE frames the principal contractor role as coordination and control across the whole construction phase. Planning and organisational capability are the critical selection factors — not just technical trade skill. A contractor who cannot demonstrate a management system for health and safety will struggle to pass client pre-qualification checks, regardless of their practical experience on the tools.

HSE inspectors assess principal contractor competence by looking at training records, supervision arrangements, monitoring activity, and whether the construction phase plan reflects the actual site conditions rather than a generic template. A plan that has never been updated since the project started is a red flag.

Pro Tip: Build CDM compliance into your job set-up SOP as a pre-start gate. Before any contractor mobilises: confirm their CSCS cards and insurance, issue the relevant sections of the construction phase plan, complete a site induction and record it. A simple sign-off sheet per contractor per visit takes five minutes and provides the evidence trail an inspector expects.

For a practical daily framework, the construction site safety checklist covers RAMS, inductions and ongoing monitoring in a format you can adapt directly.

What insurance does a contracting business need?

Insurance is not optional and it is not one-size-fits-all. Clients, funders and principal designers will ask for certificates before they allow you on site or sign a contract. Getting the right cover in place before you need it is one of the clearest contractor business tips there is.

Employers' liability insurance is a legal requirement under the Employers' Liability (Compulsory Insurance) Act 1969 the moment you take on an employee, with the law setting a minimum required level of cover.

Financial protections beyond insurance

Cashflow is the most common reason contracting businesses fail in their first three years. Three practical protections:

• Stage payments and interim valuations: Never start a project on a single lump-sum payment at completion. Agree a payment schedule tied to programme milestones or monthly valuations from the outset.
• Retention handling: Understand the retention terms in your contract before you sign. Retention monies should be clearly defined, with a release mechanism tied to practical completion and the defects liability period.
• Performance bonds and parent company guarantees: Larger clients and funders may require a bond (typically 10% of contract value) or a parent company guarantee. Factor the cost of bonding into your tender price.

Always present insurance certificates and policy schedules to clients at pre-contract stage, not after they ask. It removes a friction point and signals that your business is properly organised.

How do contracts and payment terms protect your business?

Construction contracts are where most disputes begin and where most of them could have been prevented. The single most important rule: get everything in writing before work starts, with a defined payment mechanism.

Part II of the Housing Grants, Construction and Regeneration Act 1996 defines what constitutes a "construction contract" and underpins the statutory payment protections that apply to most UK construction work. Under the Act, you have the right to interim payments, the right to suspend for non-payment, and the right to refer disputes to adjudication. If your contract does not include compliant payment terms, the Scheme for Construction Contracts applies by default.

Contract clauses to check before you sign

• Scope of works: Precisely defined, with a clear exclusions list to prevent scope creep
• Variations: A written instruction requirement before any additional work begins
• Payment mechanism: Due dates, final dates for payment, pay less notices and the notice periods that trigger them
• Certification: Who certifies payment, on what basis, and within what timeframe
• Retention: Percentage held, release conditions and the defects liability period
• Termination: Grounds for termination by either party and the financial consequences
• Adjudication: Confirmation that the statutory right to adjudication applies (it does by law, but explicit inclusion avoids argument)

Under the Construction Act, a party to a construction contract can refer a dispute to adjudication at any time. The adjudicator must reach a decision within 28 days of referral (extendable by agreement). That decision is temporarily binding — meaning the losing party must pay, even if they intend to challenge it later in arbitration or litigation. For a cash-strapped contractor, adjudication is often faster and cheaper than litigation and should be the first remedy you consider when a payment is withheld without a valid pay less notice.

JCT (Joint Contracts Tribunal) and NEC (New Engineering Contract) are the two most widely used contract families in UK construction. JCT forms are common in residential and commercial building work; NEC forms are prevalent in infrastructure and public sector projects. Both are available through their respective publishers. For a practical breakdown of how these forms work in practice, the types of construction contracts guide covers the key differences.

For complex or high-value contracts, take legal advice before signing. A solicitor experienced in construction law can identify onerous clauses that shift risk unfairly and are worth negotiating out before the contract is executed.

How do you estimate jobs, set mark-ups and manage subcontractors?

Reliable estimating is built from three components: direct cost (labour, materials, plant), overhead allocation, and margin. Getting the ratio right between those three is what separates a profitable contractor from one who wins work and loses money.

A worked example for a small residential project

Suppose you are pricing a loft conversion with a direct cost breakdown as follows:

1. Labour (self-delivered and subcontracted): £12,000
2. Materials: £8,500
3. Plant hire and scaffolding: £2,200
4. Subcontractor preliminaries (skip, welfare): £800
5. Total direct cost: £23,500
6. Overhead allocation (15% of direct cost): £3,525
7. Total cost: £27,025
8. Margin (12%): £3,243
9. Tender price (ex-VAT): £30,268

The overhead percentage should reflect your actual fixed costs: office, insurance, vehicle, software, and your own time managing the project. New businesses often underestimate this figure and price at direct cost plus margin, which means the business never recovers its running costs.

Statistic callout: Gross margins in UK residential construction typically vary depending on project type, scale, and subcontractor mix. Commercial fit-out and specialist work can carry higher margins, but also higher overhead and risk.

Subcontractor management checklist

Before any subcontractor starts on your site:

• Obtain proof of public liability insurance (minimum £2 million; check the certificate is current)
• Verify CSCS card status for all operatives they will deploy
• Issue a written subcontract that references the main contract conditions, scope, programme and payment terms
• Confirm CIS status: are they registered with HMRC? Will you deduct at the standard rate (20%) or gross (0%)?
• Issue the relevant sections of the construction phase plan and record receipt
• Complete a site induction and record it

During the works, hold regular progress meetings, document any variations in writing before they are executed, and keep a site diary. Subcontractor payment applications should be assessed against the programme and the agreed scope, not simply approved as submitted.

For a detailed look at subcontract terms and appointment templates, the UK builder subcontractor agreement guide covers the main agreement types and what to include.

How do PAYE, CIS and auto-enrolment work for contractors?

Register with HMRC for the right tax regimes before you pay anyone. That is the non-negotiable starting point. Paying a worker without the correct registration in place creates retrospective liability that is difficult and expensive to unwind.

Key employer obligations

• PAYE: Operate Pay As You Earn for all employees. Deduct income tax and National Insurance Contributions at source and pay them to HMRC monthly. Register as an employer before the first payroll run.
• National Insurance: Both employer (Class 1 secondary) and employee (Class 1 primary) contributions apply to employed workers. Employer NICs are a direct cost to the business and must be factored into your labour pricing.
• Auto-enrolment pensions: Eligible workers must be automatically enrolled into a qualifying workplace pension scheme. The Pensions Regulator sets the staging rules; as a new employer, you have duties from the day you take on your first eligible worker.
• Right-to-work checks: Conduct and record right-to-work checks for every worker before they start. Failure to do so carries civil penalties and, in serious cases, criminal liability.
• CIS monthly returns: If you are a CIS contractor (paying subcontractors for construction work), you must submit a monthly return to HMRC showing payments made and deductions taken. HMRC's CIS 340 guidance covers contractor and subcontractor roles, record-keeping requirements, and operational updates including the reinstatement of nil-return requirements from 6 April 2026.

Worker status and CIS deductions

The distinction between employee and self-employed subcontractor is not simply a matter of what you call someone. HMRC applies a multi-factor test covering control, substitution, and financial risk. Getting this wrong means unpaid PAYE and NICs, plus penalties.

CIS deductions apply when a registered contractor pays a subcontractor for construction operations. Always verify a subcontractor's CIS status through the HMRC online verification service before making the first payment, and treat CIS as a contract-level event rather than a blanket business-wide assumption.

What does it cost to start a contracting business, and when will you turn a profit?

The honest answer is that startup costs vary enormously depending on whether you are self-delivering trades or purely coordinating subcontractors, and whether you already own tools and a vehicle. The figures below are illustrative brackets to help you budget, not fixed benchmarks.

All figures are illustrative and will vary by location, scope and supplier.

Timeline to first paying client

• Weeks 1–2: Legal structure, registration, bank account, insurance
• Weeks 3–4: CSCS card (if not held), CIS/PAYE registration, first subcontractor enquiries
• Month 2: First tender submissions, website live, trade body applications (FMB, NHBC if applicable)
• Month 3: First contract signed; construction phase plan prepared
• Months 4–6: First project delivered, retention clock starts, first CIS monthly return filed
• Months 6–12: Second and third projects, overhead recovery improving, margin tracking established

Profitability expectations

The lever that moves margins most reliably is overhead recovery: as turnover grows and fixed costs stay relatively flat, net margin improves. Subcontractor mix also matters. A project where you self-deliver more trades carries higher gross margin but also higher labour management risk.

Cashflow is a separate concern from profitability. A profitable project can still cause a cashflow crisis if retentions are large, payment terms are long, or a client disputes an interim application. Stage invoicing, prompt pay less notice monitoring, and a working capital buffer of at least one month's projected costs are the practical protections.

How do you find work and win bids as a new contractor?

For most start-ups, repeat local relationships and a clear, well-structured bid win more work than broad digital marketing. That is where to focus first.

Where to find early contracts

• Local networks: Architects, surveyors, estate agents and property developers are the most reliable referral sources for residential and small commercial work. Introduce yourself in person; follow up with a one-page capability statement.
• Trade body directories: FMB membership puts you in front of homeowners actively searching for vetted contractors. NHBC registration opens doors to new-build developer work.
• Supplier referrals: Builders' merchants and plant hire companies know who is active locally and often refer contractors to clients who ask. Build those relationships early.
• Targeted tendering: Register on Contracts Finder (GOV.UK) for public sector opportunities. For private sector work, direct approaches to developers and housing associations are more effective than broad tender portals at the start.
• A basic website: You do not need a complex site. A clear homepage with your services, a project gallery, contact details, and two or three client references will convert enquiries. Google Business Profile is free and drives local search visibility.

For a detailed guide to the UK tendering process, the construction tenders guide covers timelines, pre-qualification questionnaires and bid strategy.

What a winning bid looks like

A short tender for residential or small commercial work should include:

1. Executive summary: One paragraph confirming you understand the scope and can deliver it
2. Scope of works: Precisely what is included, with a clear exclusions list
3. Price breakdown: Labour, materials, plant and preliminaries shown separately
4. Programme: Start date, key milestones, practical completion date
5. Payment terms: Stage payment schedule or monthly valuations, retention percentage
6. References: Two or three recent comparable projects with contact details

Price your first few projects to build a portfolio, but do not price below your actual cost. Winning work at a loss to gain experience is a common mistake. A better approach is to price accurately and be transparent about what you are including, which builds the trust that generates repeat work.

An operational checklist to run site, office and finance

The simplest operational control is a standard job workflow that you repeat and measure: quote, contract, mobilise, record, invoice. Every deviation from that workflow is where margin leaks and disputes begin.

Job set-up and mobilisation checklist

1. Issue a written contract or letter of intent before any work starts
2. Prepare the construction phase plan (if acting as principal contractor) and distribute to all appointed contractors
3. Confirm subcontractor insurance, CSCS cards and CIS status
4. Order materials with confirmed lead times; flag long-lead items to the programme
5. Complete site set-up: welfare facilities, signage, emergency procedures, first aid
6. Conduct and record site inductions for all operatives on day one
7. Issue RAMS (Risk Assessments and Method Statements) for all significant activities before they begin

Daily site records and communication

Keep a site diary for every working day: weather, operatives on site, work completed, instructions received, and any issues or delays. This record is your primary evidence in any payment dispute or CDM inspection. Version-control the construction phase plan and re-issue it whenever site conditions or the programme change materially.

For a practical daily reporting framework, the construction site daily reporting guide covers what to record, how to record it, and how to use those records commercially.

Choosing job management and accounting software

Look for software that handles quoting, job scheduling, subcontractor communication, invoicing and CIS tracking in one place. Switching between four separate tools creates data gaps and admin overhead that grows with every project you add.

Pro Tip: Tradewisehq is built specifically for UK trade contractors: it combines job management, scheduling, quoting, invoicing, live workforce syncing and AI-powered admin automation in a single mobile-first platform. For a growing contracting business, having quotes, job records and payment tracking in one system means your site diary, your CIS records and your invoice run are all pulling from the same data — which is where most manual admin errors disappear.

What I have learned building a contracting business from scratch

The single most important lesson is this: the businesses that survive their first three years are not the ones with the best tradespeople. They are the ones that treat administration, compliance and cashflow with the same discipline they apply to the physical work.

Most new contractors underestimate how much of the principal contractor role is coordination and documentation rather than trade skill. CDM compliance, CIS returns, contract administration and subcontractor management are not back-office distractions. They are the job. A contractor who builds a standard workflow for each of those functions from day one, rather than improvising as they go, recovers overhead faster, wins repeat clients, and avoids the disputes that drain time and money in years two and three.

The second lesson is about pricing. The temptation to price low to win early work is understandable, but it sets a market expectation that is hard to reverse. Price accurately, explain your inclusions clearly, and let the quality of your bid documentation do the differentiation work. Clients who choose on price alone are rarely the clients who pay on time.

Sources

Every contractor starting out in the UK should keep these primary sources close. They are the definitive references for registration, compliance and statutory obligations.

• MAGNUS CONSTRUCTION GROUP LTD filing history — Companies House
• Principal contractors: roles and responsibilities - HSE
• Gov
• Building Act 1966 — Section 1 Prohibition of work except under licence

Recommended

• How to win more builder contracts UK in 2026
• Construction tenders in the UK: a complete 2026 guide
• Types of construction contracts UK: a practical guide
• Construction contract management guide for UK builders