How to Check a Tradesperson Before They Start

To check a tradesperson, confirm the business is real, check they're on any register the law requires for the job, see their insurance certificate and speak to two or three people they've worked for recently. Then get a written quote and contract, pay in stages and pay by card where you can. Most of it takes twenty minutes and none of it costs anything.

The hard part is timing. The moment you most need to be careful is the moment you're least able to be: the boiler has died, it's Thursday and the one person who can come tomorrow is standing in your kitchen. So this guide is built to be used quickly, on your phone.

Consumer law and the gas register apply across the UK. Building regulations differ between England, Wales, Scotland and Northern Ireland, as do the schemes that let installers sign off their own work; where that matters, we say so.

The registers and what each one proves

Different trades sit on different registers and they don't all prove the same thing. Always check on the register's own website: a logo on a van or a quote proves nothing.

Gas: check the card, not just the name

Every gas engineer working in the UK must be registered. Their Gas Safe ID card, physical or digital, shows their photo, the business, a seven-digit licence number and when it expires. The back (or further down a digital card) lists the categories of work they're qualified for, so check it names your job: registered for cookers is not registered for boilers. The licence is renewed every year, so an expired card is a reason to stop.

Competent person schemes

In England, plenty of home work is notifiable under building regulations, from a new consumer unit to replacement windows. An installer in a competent person scheme can certify their own work and tell the council for you. GOV.UK says you should get the certificate within eight weeks; it also shows up in a buyer's solicitor's searches when you sell. Our guide to planning permission or building regulations covers which jobs need approval.

Wales sets its own building regulations, Scotland uses building warrants and in Northern Ireland building control sits with the 11 district councils. Outside England, ask your council what the job needs before it starts.

TrustMark and trade associations

TrustMark is the Government Endorsed Quality Scheme for work in and around the home: firms are vetted, there's a complaints process and written contracts are expected. It isn't a competent person scheme, so it doesn't let anybody sign off building regulations work. Check trade association membership (the Federation of Master Builders, for example) on the association's own website. Membership tells you something about the firm; it doesn't promise perfect work.

Checking the business behind the van

A register tells you somebody is qualified. These checks tell you the business is who it says it is.

• A limited company? Search Companies House free for the registered address, incorporation date, directors past and present, filings, previous names and any insolvency. A new company isn't a problem in itself; a new company with an old trading name is worth a question.
• A sole trader? They won't be on Companies House. Ask for a full name, a trading address and a landline, then ring it. Citizens Advice says to be wary of a trader who only gives a mobile number.
• Charging VAT? HMRC's free VAT number checker returns the name and address the number is registered to, which should match the quote.
• County court judgments. Anyone can search the official register through TrustOnline, run by Registry Trust for the Ministry of Justice, for a fee.
• References. Ask for two or three recent jobs like yours and speak to those people yourself, because written references aren't always genuine. Go and look at the work if you can. Walk away from anybody who won't give references.
• Reviews. Read the bad ones too. How a firm answers a complaint tells you more than a page of five-star ratings.

Insurance: the question and the follow-up

"Are you insured?" gets a yes from everybody, including the people who aren't. Ask to see the certificate instead.

Public liability insurance covers injury to people and damage to property (yours or your neighbour's) caused by the work. No general law requires a tradesperson to have it. The cover the law does make compulsory for most businesses with staff is employers' liability insurance, which protects their employees rather than you. So public liability is the trader's choice, which is exactly why it's worth asking about.

On the certificate, check three things: the name matches the business you're hiring, the dates cover the whole job and the cover suits the work. Taking out a wall carries more risk than fitting a blind.

Ask two more questions while you're there. Is your deposit protected if the firm stops trading? And is the guarantee insurance-backed? That means, as Citizens Advice puts it, a policy is in place so the guarantee can still be honoured if the trader goes out of business. Without one, a workmanship guarantee lasts as long as the firm does.

Comparing quotes like for like

Citizens Advice suggests written quotes from at least three traders. The cheapest is only the cheapest if all three describe the same job, so line them up against this list. A price far below the others isn't a bargain until you know what's missing from it.

If two quotes differ wildly on one line, ask both traders why. The answer often tells you more than the price does.

The questions that prevent the arguments

Almost every dispute about building work traces back to something that was never discussed, rather than something agreed and then broken. Ask these before you agree anything, then put the answers in the contract.

1. Who tells building control and who gets me the certificate? If the answer is vague, assume it's you.
2. What are the start and finish dates? And what happens if they slip?
3. Who takes the waste away? Skips and tip runs are a common late extra.
4. What does making good include? Plastering, painting and putting the carpet back are three different jobs.
5. Will you use subcontractors? If so, are they registered where they need to be?
6. What happens if you find something unexpected? Agree that any extra is quoted and approved in writing before it's done.
7. Could I buy the materials myself? Citizens Advice suggests this as a way to avoid a large deposit.
8. What's the guarantee and who stands behind it? A boiler maker's warranty usually depends on a yearly service (see what a boiler service includes).

If the answers come easily, you've probably found somebody who has done this before.

Put it in a contract

For anything more than a small repair, ask for a written contract; TrustMark tells homeowners to always use one. Citizens Advice suggests it covers the dates, delays, tidying up, who pays for materials, any subcontractors and how and when you'll pay. Read it before you sign, not on the morning they arrive.

Money: deposits, stages and the card

No law sets how big a deposit can be. Citizens Advice suggests avoiding one if you can and, if you can't, not agreeing to more than 25%. You could buy the expensive materials yourself instead, or use a service that holds the money in a neutral account until agreed stages are finished (check it's registered with the Financial Conduct Authority). Always get a receipt.

For bigger jobs, agree stage payments tied to things you can see: materials delivered, first fix finished, plastering done, snagging signed off. TrustMark's rule is to pay only for work that's been done. Hold the final payment until the job is finished and you've checked it: it's your best chance to get small faults put right.

How you pay changes what protects you

So a deposit paid by credit card on a £9,000 job can bring the whole job under section 75 of the Consumer Credit Act 1974, not just the deposit. That one choice is probably the most valuable thing on this page.

Warning signs

None of these proves somebody is a rogue trader. Each one is a reason to slow down.

• They knocked on your door to say they'd noticed a problem with your roof or chimney.
• The price is only good if you agree today.
• They want cash, or the whole price up front.
• They won't put a quote or a contract in writing.
• There's only a mobile number: no address, no landline.
• They won't give references.
• The price is far below everybody else's.
• They push to start straight away on a job that isn't urgent.
• They talk you out of involving building control, or say the certificate isn't needed.

Before they start and before they leave

Two short checklists, one for the first morning and one for the last afternoon.

Before they start

1. Quote and contract agreed in writing, with a copy each.
2. Insurance certificate seen, in date and in the right name.
3. Registration checked on the register's own website.
4. Building control sorted: who is notifying, or has the application gone in? Planning permission in hand too, if the job could need it.
5. Payment stages written down, with what triggers each one.
6. If the work touches a wall you share with a neighbour, check whether the Party Wall etc. Act 1996 applies (England and Wales).
7. Photos of the area as it is now, so nobody argues later about what was already damaged.
8. Parking, access and working hours agreed; the stopcock and fuse board pointed out.

Before they leave

1. Walk round together and list any snags in writing, with a date to fix them.
2. Test what was installed: run the heating and the taps, try the switches, open and lock the windows.
3. Ask for the certificate, or when it will arrive. For notifiable gas work such as a new boiler, the engineer must notify it within 30 days; the certificate follows by post.
4. For a new boiler, check the Benchmark checklist is filled in and signed.
5. Register any manufacturer's warranty. Some boiler makers ask for this within 30 days of installation or the guarantee is cut short.
6. Collect manuals, spare keys, serial numbers and paint or product codes.
7. Check the invoice matches the quote plus any extras agreed in writing.
8. Only then make the final payment.

If something goes wrong

Under the Consumer Rights Act 2015, which applies across the UK, a trader must do the work with reasonable care and skill. What they told you or wrote down about the service can become part of the contract. With no fixed price you pay a reasonable one; with no fixed date the work must be done within a reasonable time.

If the work falls short, your first remedy is to have it done again properly, at the trader's cost. If that's impossible or doesn't happen, you can ask for a price reduction, which can be a full refund.

What to do, in order:

1. Gather the paperwork, photos and notes with dates.
2. Tell the trader in writing what's wrong, mention the Consumer Rights Act and give a reasonable deadline to put it right.
3. If they belong to TrustMark or a trade association, use its complaints process.
4. If you paid by card, ask your card provider about section 75 or chargeback.
5. Get free advice. In England and Wales, the Citizens Advice consumer helpline is on 0808 223 1133 (Welsh language 0808 223 1144) and can pass complaints to Trading Standards. In Scotland, contact Advice Direct Scotland. In Northern Ireland, Consumerline is on 0300 123 6262 and can forward complaints to the Trading Standards Service.
6. Court is the last resort. The paperwork you kept is what carries it.

If gas work looks unsafe, or was done by somebody who isn't registered, tell Gas Safe on 0800 408 5500. Citizens Advice has more on problems with building work.

What to keep when it is finished

The job ends, the mess goes and this is where most of us stop. Ten more minutes now saves hours later, often years later when you sell.

• The quote, contract and any agreed changes. They show what was promised.
• The final invoice and proof of payment, including the card statement.
• The compliance certificate, from Gas Safe, the competent person scheme or the council. This is what a buyer's solicitor asks for; an invoice only proves you paid somebody.
• Guarantees and warranties, with proof of any registration; the insurer's details if the guarantee is insurance-backed.
• Manuals, serial numbers and the Benchmark checklist for anything installed.
• Photos of anything now hidden: pipe runs before the floor went down, cable routes before the plaster.
• The trader's details: name, registration number, phone number and what they did.

Our guide to how to prove work was done on your home goes further, including how to replace a lost certificate. If paperwork from earlier jobs is missing, building your home's service history shows how to piece it back together.

If you use homehogs, the trade goes on your list of trades with the job they did. The certificate, guarantee and invoice sit on that job's record, with a reminder before the guarantee ends.

Sources

• Gas Safe Register: the Gas Safe ID card
• GOV.UK: Use a competent person scheme
• GOV.UK: Competent person schemes, current schemes
• mygov.scot: Building regulations (building warrants)
• TrustMark: homeowners
• GOV.UK: Get information about a company
• GOV.UK: Check a UK VAT number
• TrustOnline: Register of Judgments, Orders and Fines
• GOV.UK: Employers' liability insurance
• Citizens Advice: Before you get work done on your home
• Citizens Advice: Cancelling building or decorating work
• Citizens Advice: Getting your money back if you paid by card or PayPal
• legislation.gov.uk: Consumer Credit Act 1974, section 75
• legislation.gov.uk: Consumer Rights Act 2015, Part 1 Chapter 4 (services)
• legislation.gov.uk: Consumer Contracts (Information, Cancellation and Additional Charges) Regulations 2013
• GOV.UK: Consumer advice helplines
• Citizens Advice: If you need more help about a consumer issue
• nidirect: Contact Consumerline
• GOV.UK: Party walls and building work

Last fact-checked 5 October 2026.