Does a plumber need public liability insurance by law?

No law requires a plumber to hold public liability insurance, although many customers, contractors and schemes ask for it. Employers' liability insurance is different: it is compulsory once you employ staff, with a few exemptions, under the 1969 Act in England, Wales and Scotland and under separate Northern Ireland law.

Do I have to declare cash jobs?

Yes, if it's trading income. Cash counts the same as a bank transfer, so it goes in your records, and on your tax return if you have to send one.

Can I work for an employer and do plumbing jobs on the side?

Yes, GOV.UK says you can be employed and self-employed at the same time. Check your employment contract first, because some don't allow it, and remember you may have to tell HMRC about the extra income.

Working for yourself

Running Jobs and Working for Yourself · Plumbing

8 min read · self-test time extra

Plenty of plumbers end up working for themselves, or mix it with subcontracting. Here's how self-employment works, how CIS deductions are taken, what insurance the law asks for, and where schemes and landlords fit in.

An employee is paid through payroll. A subcontractor on a building firm's jobs may have deductions taken under the Construction Industry Scheme, which count towards their tax and National Insurance. Someone with their own customers quotes, invoices and keeps the records, and HMRC's guidance sets out the current rules.

Employers' liability insurance is compulsory once a business takes on staff, with a few exemptions, under the 1969 Act in England, Wales and Scotland and under separate law in Northern Ireland. Public liability cover is not a legal requirement for a plumber, though most hold it. A business moving waste in its van registers as a waste carrier with its nation's regulator.

WaterSafe lists approved contractors for water fittings, the Gas Safe Register is for gas work, and MCS certifies small renewable installations. In a rented home the landlord arranges a yearly gas check by a Gas Safe registered engineer and assesses the Legionella risk, while the plumber does the water side and reports what they find.

Reviewed 4 November 2026

Know what the law asks, and what each scheme covers

Employers' liability insurance once you take on staff, waste carrier registration if you move waste, and good records come with running a plumbing business; public liability cover is a common choice. WaterSafe, the Gas Safe Register and MCS cover different kinds of work.

Employed, subcontracting or self-employed: what's the difference?

Plenty of plumbers do more than one of these. As an employee, you're paid through payroll. As a subcontractor, you work for a contractor such as a building firm, on their jobs. With your own customers, you find the work, quote, invoice and keep the records. GOV.UK says someone is probably self-employed if they're self-employed for tax purposes and most of these are true: they bid or quote for work, aren't directly supervised, send invoices, pay their own National Insurance and tax, and don't get holiday or sick pay. You can also be both at once, such as working for an employer in the day and doing your own jobs in the evenings.

Should a plumber be a sole trader or a limited company?

GOV.UK says most businesses register as one or the other. A sole trader is the simplest to set up and keep records for. You make the decisions and keep the profits after tax, but you're personally responsible for all the business's debts. A limited company is legally separate from the people who own it, and they're responsible for its debts only up to the value of their investment, though it comes with more formal duties to keep up. GOV.UK says it's usually easier to move from sole trader to limited company than the other way round, so plenty of people start simple. An accountant can tell you what suits your numbers.

How do you register as a self-employed plumber?

As a sole trader, you register for Self Assessment with HMRC. You have to tell HMRC by 5 October after the end of the tax year if you need to send a return for that year, and the tax year runs from 6 April to 5 April. If your trading income for the year is £1,000 or less, you may not have to tell HMRC, though there are cases where you still must. Start keeping records from your first job, not when you get round to registering.

What is CIS, and how does it affect a plumber?

Under the Construction Industry Scheme, a contractor takes money out of a subcontractor's payments and passes it to HMRC. Those deductions count as advance payments towards your tax and National Insurance. GOV.UK lists installing systems for heating, power, water and ventilation among the work it covers, along with alterations and repairs. If you're registered, the contractor deducts 20%. If you aren't, it's 30%. You can apply for gross payment status if you don't want deductions taken in advance. Subcontractors don't have to register, and employees don't need to. Jobs for your own customers work differently: they pay you, and you invoice them and keep the records. If you start paying subcontractors for construction work yourself, you'll need to register as a contractor.

What records does a self-employed plumber need to keep?

Keep your quotes, invoices, receipts and job notes. You need them for your tax return, and they're your evidence if a customer disputes the work. GOV.UK says to keep records of business income and expenses for at least 5 years after the 31 January submission deadline for that tax year. Cash jobs are income like any other, so they go in too. Making Tax Digital for Income Tax is also coming in by stages, based on your qualifying income. The highest earners started from 6 April 2026, then it's over £30,000 from 6 April 2027 and over £20,000 from 6 April 2028. Check GOV.UK for how yours is worked out.

What insurance does a self-employed plumber need?

Two kinds get mixed up. Employers' liability insurance is compulsory as soon as you become an employer, with a few exemptions, under the 1969 Act in England, Wales and Scotland and under separate law in Northern Ireland. For the Great Britain rules, GOV.UK says it must cover at least £5 million and come from an authorised insurer, and you can be fined £2,500 for every day you aren't properly insured. You don't need it if you only employ a family member, or someone based outside England, Scotland and Wales. Public liability cover is there for when your work injures someone or damages their property. No law makes a plumber hold it, but many customers, contractors and schemes ask for it.

Do plumbers need a waste carrier licence?

It's a registration rather than a licence, and yes, if your business carries waste in its van. That includes your own waste, such as old pipe and rubble. You register with the regulator for your nation: the Environment Agency in England, Natural Resources Wales, SEPA in Scotland or the Northern Ireland Environment Agency, and each has its own process. For England, GOV.UK says you can get an unlimited fine if you don't register. It also says registration is usually free if you only transport waste you produce yourself, but don't count on that as a plumber. Under the regulations for England and Wales, the own-waste exception doesn't cover construction or demolition waste, and construction there includes repair and alteration. So expect to pay the fee, and you'll be told when you register whether you're upper tier, which renews every 3 years, or lower tier.

Which schemes should a self-employed plumber join?

They cover different work, and only one of these is a legal must for the work it covers. Gas businesses have to be on the Gas Safe Register, in Great Britain and in Northern Ireland, so don't touch gas without it. WaterSafe brings together the approved contractor schemes for water fittings across the four nations. An approved contractor can do some work without telling the water supplier first, and can give the customer a certificate that it meets the rules. In England, a competent person scheme lets a registered installer confirm that certain building work meets the Building Regulations, instead of the customer going through building control. The other nations have their own arrangements. MCS certifies small-scale renewable installations, and it matters if your customers want a heat pump grant.

Working for landlords and letting agents

In Great Britain, the landlord arranges a yearly gas check by a Gas Safe registered engineer and assesses the Legionella risk, while the plumber does the water side and reports what they find. If you aren't Gas Safe registered, the gas check isn't yours to take on. Agree who's paying before you start, since the agent who rings you may not be the person who pays the bill, and put what you found in writing.

Working for yourself: common questions

Does a plumber need public liability insurance by law?: No law requires a plumber to hold public liability insurance, although many customers, contractors and schemes ask for it. Employers' liability insurance is different: it is compulsory once you employ staff, with a few exemptions, under the 1969 Act in England, Wales and Scotland and under separate Northern Ireland law.
Do I have to declare cash jobs?: Yes, if it's trading income. Cash counts the same as a bank transfer, so it goes in your records, and on your tax return if you have to send one.
Can I work for an employer and do plumbing jobs on the side?: Yes, GOV.UK says you can be employed and self-employed at the same time. Check your employment contract first, because some don't allow it, and remember you may have to tell HMRC about the extra income.

Sources

GOV.UK: employers' liability insurance — When employers' liability insurance is compulsory for an employer, the exemptions, and displaying the certificate.
GOV.UK: Construction Industry Scheme — Who registers for CIS and how contractors make deductions from subcontractors' payments.
GOV.UK: register as a waste carrier — Who needs to register to carry waste, including a business carrying its own waste.
legislation.gov.uk: Waste (England and Wales) Regulations 2011, regulation 24 — Carriers of only their own waste as specified persons, except for construction or demolition waste, which includes repair and alteration.
HSE: Legionella and Legionnaires' disease — How Legionella risk is assessed and controlled in Great Britain, including the duties of landlords and employers.
GOV.UK: employment status, self-employed and contractor — The signs someone is probably self-employed, and being employed and self-employed at the same time.
GOV.UK: legal structures for a business — Sole traders and limited companies, who's responsible for the debts, and moving from one to the other.
GOV.UK: check how to register for Self Assessment — Telling HMRC by 5 October if you need to send a return for the previous tax year.
GOV.UK: tax-free allowances on property and trading income — The trading allowance of up to £1,000, and when you may still have to tell HMRC.
GOV.UK: what you must do as a CIS subcontractor — The 20% and 30% deductions, gross payment status and when an employee doesn't register.
GOV.UK: work covered by CIS — Installing heating, power, water and ventilation systems, alterations and repairs as work CIS covers.
GOV.UK: business records if you're self-employed — Records of income and expenses, kept for at least 5 years after the 31 January deadline.
GOV.UK: when you need to use Making Tax Digital for Income Tax — The qualifying income thresholds and dates for Making Tax Digital for Income Tax.
WaterSafe: the national register of approved plumbers — WaterSafe as a directory and accreditation body for plumbers working to the water fittings rules.
MCS: standards and tools library — The MCS installation standard for heat pumps (MIS 3005-D), which calls for a room-by-room heat loss calculation before a system is designed.

Report a mistake

Key numbers

28 days: In Great Britain, existing tenants get a copy of the landlord's gas safety record within this time of the check.
20%: What a contractor deducts from a subcontractor registered for CIS.
30%: What a contractor deducts under CIS if the subcontractor hasn't registered.
5 years: How long to keep records after the 31 January deadline for that tax year, at least.

Common mistakes

Treating public liability as a legal requirement, or employers' liability as optional.
Leaving cash jobs out of the records.
Carrying waste in the van without registering as a waste carrier.
Taking on a landlord's gas safety check without Gas Safe registration.

Lessons on the plumbing path

Employed, subcontract or self-employed
Insurance and paperwork
Schemes and registrations, accurately
Landlord and letting-agent work

Terms to know

Before you start: some plumbing work is regulated or notifiable

Some water fittings work needs notice to, and consent from, the water supplier before it starts. Check the rules where you live.

Gas work is for competent workers covered by a Gas Safe registered business in Great Britain. Northern Ireland has separate gas regulations. Do not work on gas pipes or appliances yourself.

In England, installing an unvented hot-water system over 15 litres is notifiable building work: use a competent installer registered with a competent-person scheme, or tell building control before work starts. Leave this work to a suitably skilled person.

Wales, Scotland and Northern Ireland have their own water and building rules; check which apply before work starts. Electrical connections belong with an electrician.

This guide does not qualify you or make you competent, approved or registered for plumbing, gas or unvented work.