How to verify a UK contractor's licence in 2026 (3-minute guide)
The United Kingdom does not issue a single builder's licence. Three registers matter for any London or UK residential build — CIOB for professional qualification, Gas Safe for gas (statutory), and NICEIC for electrical work (Part P). This guide walks the tri-board check the same way our free contractor-check tool automates it.
There is no single UK builder's licence
Unlike California (CSLB), Australia NSW (Fair Trading HBL), or Singapore (BCA), the UK has no statutory contractor register covering general building work. Gas Safe is statutory for gas. NICEIC (and its peers NAPIT, ELECSA, STROMA) covers Part P electrical. CIOB is a royal-chartered professional body for individuals. TrustMark is the government-endorsed cross-scheme quality mark. A London GC on a £250,000 Victorian terrace refurbishment should be able to show you qualifications from at least two of these — typically CIOB + Gas Safe for the principal and subcontractor structure.
Six checks to run — 3 minutes total
- Step 1
Ask the builder which registers they're on
The UK does not issue a single 'builder's licence' the way California or NSW does. Instead, accreditation is split across three independent registers: CIOB (Chartered Institute of Building — professional membership), Gas Safe (statutory for any gas appliance or boiler work), and NICEIC (electrical installer certification required in practice for notifiable electrical work under Part P). A legitimate London GC should be able to name which of the three applies to your project and give you their registration number for each. Any builder who performs gas work without Gas Safe registration is committing a criminal offence under the Gas Safety (Installation and Use) Regulations 1998.
- Step 2
Check CIOB membership (professional qualification)
Open ciob.org/membership/find-member. Enter the principal's name or membership number. CIOB classifies members as Student, Affiliate, Incorporated (ICIOB), Member (MCIOB), or Fellow (FCIOB). For a residential renovation above £25,000, you want MCIOB or FCIOB — that confirms the principal has passed CIOB's professional review. CIOB is voluntary (unlike Gas Safe) so absence does not mean the builder is illegal, but its presence is a strong positive signal on complex projects.
- Step 3
Check Gas Safe for any gas work (statutory)
Open gassaferegister.co.uk/find-an-engineer. Enter the Gas Safe registration number (format: ######, 6 digits). The result page shows the engineer's name, the company name, the expiration date of their registration, and — critically — the qualifications they hold. Gas Safe registration is trade-specific: a Gas Safe engineer qualified for domestic boilers may not be qualified for LPG, commercial catering, or room-sealed appliances. If any part of your project touches a gas line, boiler, cooker, or flue, a non-Gas-Safe tradesperson cannot legally touch it. Full stop.
- Step 4
Check NICEIC for electrical installer certification
Open niceic.com/find-a-contractor. Enter the company name or NICEIC number. NICEIC certifies under the Domestic Installer Scheme (household consumer units, sockets, lighting) and the Approved Contractor Scheme (commercial / industrial). Under Part P of the Building Regulations, notifiable electrical work in England and Wales must be either self-certified by a registered installer or signed off by a Local Authority Building Control inspector after the fact. Using a non-NICEIC (or equivalent — NAPIT, ELECSA, STROMA) electrician means you'll likely pay a Local Authority inspector £300–£700 separately to sign off the work. NICEIC carries a workmanship warranty on certified installations.
- Step 5
Cross-check TrustMark (government-endorsed quality mark)
TrustMark is a Government Endorsed Quality Scheme covering trades across England, Scotland, Wales, and Northern Ireland. Open trustmark.org.uk/find-a-tradesperson and search by trade + postcode. TrustMark members are vetted on technical competence, trading practice, and customer service — a TrustMark listing provides a meaningful cross-check on CIOB/Gas Safe/NICEIC because it ties those accreditations to a consumer-complaint framework. No TrustMark is not a red flag on its own, but multiple TrustMark listings with the Competent Person Scheme ticked is the strongest signal short of personal referral.
- Step 6
Check insurance — Public Liability + Employer's Liability (statutory)
UK builders must carry Employer's Liability Insurance (£5,000,000 statutory minimum under the Employers' Liability (Compulsory Insurance) Act 1969) if they employ anyone — and Public Liability Insurance (typically £2,000,000 to £5,000,000, not statutory but required by virtually every UK main contractor) for damage to your property during works. Ask for the certificate of Employer's Liability — the insurer must issue one, display it at the workplace, and display it electronically. Confirm the policy is current and the cover limit is adequate for your project value. For projects above £10,000, also ask whether the builder participates in FMB Mastercert or JCT Home Building Contract — both carry deposit-protection and dispute-resolution frameworks.
Red flags — walk away if you see any of these
- Any gas work being performed by someone not on the Gas Safe register — this is a criminal offence
- Notifiable electrical work (new circuits, consumer unit, bathroom) by a non-NICEIC / non-NAPIT / non-ELECSA installer without prior Building Control notification
- Deposit request above 10% of contract value, or above £10,000 regardless of percentage
- No Employer's Liability certificate or out-of-date cover
- “I'll subcontract the gas/electrical out” with no specific name of the Gas Safe / NICEIC subcontractor
- Claims of “CIOB certified” without a membership grade (MCIOB / FCIOB) or number you can look up
Want this automated? Use AskBaily's free tool.
Our /tools/contractor-check tool runs the tri-board composite query — pick “United Kingdom” in the jurisdiction picker, prefix the number with CIOB:, GAS:, or NICEIC: (or leave unprefixed to try CIOB first), and we'll return a combined scorecard covering all three registers plus TrustMark cross-check. Free, no sign-up, no email capture.
We don't compete with the registers — we route you to them. If AskBaily's read ever contradicts the live register, trust the register.
Frequently asked questions
Why does the UK have three registers instead of one contractor licence?
Historical accident. Gas Safe (formerly CORGI) was created under the Gas Safety Regulations 1998 as a statutory register to replace voluntary certification. NICEIC was created in 1956 by the electrical industry itself, before any statutory electrical-installer scheme existed. CIOB is a royal-chartered professional body dating to 1834 — it certifies individuals, not companies. England, Scotland, Wales, and Northern Ireland each have slightly different Building Regulations and Building Control schemes, and unlike the Republic of Ireland's CIRI or Australia's state-level VBA / NSW Fair Trading, there has never been a single UK-wide statutory contractor register.
Is a 'Gas Safe registered' plumber the same as a Gas Safe engineer?
No, and this is worth checking carefully. A plumber can hold Gas Safe registration only if they've completed the relevant ACS (Accredited Certification Scheme) qualifications — CCN1 for domestic natural gas, CMET1 for metering, etc. Check the Gas Safe register page for the specific qualifications listed. A domestic-qualified engineer cannot legally work on commercial catering equipment, and vice versa. The qualification list on the register is the source of truth — not what's on the van.
What is the difference between Part P self-certification and Local Authority sign-off?
Under Part P of the Building Regulations, notifiable electrical work (new circuits, consumer unit replacement, work in special locations like bathrooms or outdoors) in England and Wales must be certified. NICEIC (and NAPIT, ELECSA, STROMA) registered installers can self-certify — they submit the Electrical Installation Certificate (EIC) directly to the Local Authority via the scheme provider. A non-registered electrician cannot self-certify, so the homeowner must notify Building Control before work starts and pay for inspection (£300–£700 typically). Self-certification is faster, cheaper, and carries a workmanship warranty.
How much should I pay as a deposit on a UK build?
No more than 10% of the contract value, and ideally less. JCT Home Building Contract (the standard residential contract published by the Joint Contracts Tribunal) does not require a deposit at all — it specifies stage payments tied to milestones. If your builder asks for 25% or more up front, that's a red flag regardless of their CIOB/Gas Safe/NICEIC status. For deposits above £100, credit-card payment gives you Section 75 Consumer Credit Act protection. FMB Mastercert also carries a deposit protection scheme up to the stage-payment value.
The builder isn't on any of these registers but my neighbour used them. Is that OK?
For non-gas, non-notifiable-electrical work — painting, plastering, kitchen fitting, loft conversion without structural work — there is no statutory register requirement, and personal referrals are genuinely valid. But for anything that touches gas (boiler, cooker, fireplace) or adds a new electrical circuit, the builder MUST subcontract to someone on Gas Safe / NICEIC. Ask who the subcontractor is and verify that subcontractor's registration before signing the main contract. 'My mate does it' is not a defence if the work later fails Building Control.
Can I use AskBaily's tool instead of checking all three registers myself?
Yes. Our /tools/contractor-check runs a composite lookup — enter the prefix CIOB:, GAS:, or NICEIC: followed by the registration number, and we query all three registers and return a combined scorecard. The underlying data is the same public data you'd get by visiting each register directly. We cache results for 24 hours and re-query on demand. If our result ever disagrees with a register's live portal, trust the register — they are the source of truth, we are a mirror.