How to Start a Plumbing Business in the UK

Plumbing is one of the most reliable trades in the UK — the demand never stops. From emergency repairs to bathroom installations, plumbers who run a professional business can build a very comfortable living. Here is how to get set up properly.

Qualifications

• NVQ Level 2 or 3 in Plumbing and Heating — the standard qualification
• City & Guilds 6035, 6189, or equivalent
• CSCS card — required for construction site work
• Unvented hot water systems — Level 3 qualification required to work on unvented cylinders (G3 Building Regulations)
• Water regulations — understanding of Water Supply (Water Fittings) Regulations 1999

Gas Safe Registration

If you work on gas appliances (boilers, cookers, fires), you must be Gas Safe registered. It is illegal to carry out gas work without registration. You need relevant ACS (Accredited Certification Scheme) qualifications, renewed every 5 years. Gas Safe registration costs around £400 per year.

If you do not do gas work, Gas Safe registration is not required — but adding gas qualifications significantly increases your earning potential.

Sole Trader or Limited Company?

Most plumbers start as sole traders. CIS applies if you subcontract for construction businesses. A limited company may be worth considering at higher profit levels.

Registering with HMRC

Register for Self Assessment within three months. CIS registration as a subcontractor. VAT at £90,000 — many plumbers reach this threshold within a few years. The domestic reverse charge applies to plumbing work supplied to VAT-registered, CIS-registered businesses.

Insurance

• Public liability — essential. £2–5 million minimum.
• Employers' liability — if you employ anyone
• Professional indemnity — if you provide design or advisory services
• Tools and equipment — plumbing tools are expensive and often targeted by thieves
• Vehicle insurance — commercial cover
• Personal accident

Expect £400–£1,200 per year.

Claimable Expenses

• Materials — copper pipe, plastic pipe, fittings, solder, sealant, valves, taps
• Tools — pipe cutters, wrenches, soldering equipment, pipe benders, drain rods, cameras
• Vehicle costs — fuel, insurance, maintenance, or 45p per mile
• Gas Safe registration fees
• Training and qualifications — ACS renewals, unvented courses, new skills
• CSCS card fees
• Insurance premiums
• PPE and workwear
• Phone and communications
• Marketing — van livery, website, Google Ads, Checkatrade
• Home office costs
• Waste disposal
• Subcontractor payments
• Accountancy fees

Accounted handles your expenses automatically, matching receipts to bank transactions.

Industry-Specific Tax Tips

CIS Deductions

Keep every CIS statement. Separate labour and materials on invoices. Deductions offset your tax bill.

Gas Safe Costs

Gas Safe registration and ACS renewal costs are fully deductible business expenses.

Emergency and Weekend Work

If you offer emergency callouts, this additional income is taxable like any other. Keep records of all callout fees.

Capital Allowances

Expensive equipment — pipe freezing kits, CCTV drain cameras, power flushers — qualifies for Annual Investment Allowance.

Building Your Business

• Emergency availability — 24/7 or extended hours significantly increases your earning potential
• Google My Business and local SEO — most plumbing work comes from search
• Reviews — encourage every customer to review
• Checkatrade, MyBuilder, Rated People — online directories
• Partnerships — estate agents, property managers, landlords
• Repeat clients — boiler servicing creates annual recurring relationships

Bookkeeping Tips

• Separate business and personal finances
• Record all income — including emergency cash callouts
• Track CIS deductions
• Keep materials receipts — organised by job
• Reconcile weekly
• Set aside 25–30% of profits for tax

Accounted is built for UK tradespeople. CIS tracking, expense management, and tax-ready records.

Key Deadlines

• 19th monthly — CIS returns (if engaging subcontractors)
• 31 January — Self Assessment and payment
• 31 July — second payment on account
• Quarterly — VAT returns if registered
• Every 5 years — ACS renewal

Getting Started

Plumbing offers one of the most secure paths to self-employment in the UK. Get qualified, consider Gas Safe registration, and keep your finances flowing smoothly from day one.

Ready to pipe up about your business finances? Sign up for Accounted and let Penny keep your books in order while you keep the water flowing.