Gas Safe Registration — How to Get Registered and Stay Legal (2026)

The Law — You Cannot Work on Gas Without Being Registered

The legal foundation is the Gas Safety (Installation and Use) Regulations 1998, usually shortened to GSIUR. Regulation 3 makes it an offence for any person to carry out gas work unless they are a member of a class of persons approved by the Health and Safety Executive (HSE) — and since 2009 that approved body has been the Gas Safe Register. It does not matter whether the work is paid or a favour for a relative: installing, servicing, repairing, maintaining or commissioning a gas appliance without registration is illegal.

The Gas Safe Register replaced CORGI as the official gas registration body on 1 April 2009. It is the only official register for businesses and engineers who are legally allowed to work on gas in Great Britain, the Isle of Man and Guernsey. Enforcement sits with the HSE, which can and does prosecute illegal gas fitters. Penalties can include unlimited fines and, in cases involving death or serious injury, custodial sentences.

How You Qualify — The ACS Route

To get on the register you must first prove your competence. For most engineers this is done through the ACS — the Accredited Certification Scheme. ACS is a set of assessments, taken at an approved assessment centre, covering both gas safety knowledge and practical competence on specific types of appliance. You cannot simply turn up and register; you must hold valid ACS certificates (or equivalent qualifications) for the categories of work you intend to do.

The core domestic certificate is CCN1 (Core Domestic Gas Safety). This is the foundation everyone needs before adding appliance modules. On top of the core you add the appliance categories relevant to your work — for example CENWAT for central heating boilers and water heaters, CKR1 for cookers, and HTR1 for gas fires and wall heaters. You can only legally work on appliance types for which you hold the matching category.

New entrants who have not worked in the trade before generally cannot go straight to ACS. The recognised route in is a managed learning programme — typically an NVQ or equivalent vocational qualification combined with on-site experience under a registered engineer — before sitting the ACS assessments. Experienced engineers re-entering the trade usually take the ACS reassessment route directly. Either way, the certificates you hold define the exact scope of work you are allowed to register for.

Quick Reference: Common ACS Categories

This is not the full list — there are categories for commercial gas, catering, laundry and other specialist areas. Only register for, and only carry out, the categories you actually hold.

How to Register Your Business

A common point of confusion: it is the business that registers with Gas Safe, and individual engineers are listed against that business. If you are a sole trader, you register as a business in your own name — there is no barrier to one-person operations. If you employ or subcontract other engineers, each one must hold their own valid ACS certificates and be added to your business's registration.

To register a new business you apply to Gas Safe Register, provide evidence of each engineer's qualifications, and pass a registration assessment that checks your tools, premises and working practices meet the required standard. Once approved, your business appears on the public register and each engineer is issued a Gas Safe ID card. You must keep your details current — changes of address, new engineers joining, or engineers leaving all need to be notified.

Costs, Annual Renewal and 5-Year Reassessment

Registration is not a one-off. There is an initial registration fee to join, then an annual renewal fee to keep your business on the register, with a per-engineer charge on top for each additional registered operative. Fees are reviewed periodically by Gas Safe, so always check the current figures on the official site before budgeting — but plan for a recurring annual cost, not a single payment.

Separately from the annual renewal, your competence itself expires. Each ACS category must be reassessed every 5 years to remain valid. As the five-year point approaches you re-sit the assessments for each category you hold (CCN1, CENWAT and so on). Let a category lapse and you are no longer legally permitted to work on that appliance type, even if your business registration is otherwise current. Diarise both the annual renewal and the rolling five-year reassessment dates well in advance — a lapsed certificate means lost work and potential illegal trading.

The Gas Safe ID Card

Every registered engineer carries a Gas Safe ID card, and it is the single most important proof of legitimacy on the doorstep. The front of the card shows the engineer's photo, their licence number, the business they work for, and the card's start and expiry dates. The back is what really matters: it lists the specific categories of gas work the engineer is qualified and registered to carry out.

This back-of-card detail is the proof that an engineer is competent for the job in front of them. An engineer qualified for boilers (CENWAT) but not cookers (CKR1) must not work on a cooker — and the card makes that visible. Always carry your card, keep it in date, and be ready to show it. Telling a customer you are "Gas Safe" means nothing if the card has expired or the relevant category isn't on the back.

Only Work Within Your Categories

It is worth repeating because it is where good engineers get caught out. Being Gas Safe registered does not authorise you to work on every type of gas appliance — it authorises you for the categories on your card. Working outside them is no different in law from working with no registration at all. If a job needs a category you don't hold, either gain the qualification or refer the work to an engineer who has it. Drifting into commercial, LPG or catering work on the back of a purely domestic registration is a serious compliance failure.

How Customers and Landlords Check the Register

You should expect — and encourage — customers to verify you. Anyone can check an engineer or business for free on the Gas Safe Register website or by phone. Landlords in particular have a legal duty to ensure gas work in their rental properties is carried out by a registered engineer, so they often check before booking.

Make the verification steps easy to explain to customers:

• Always check the engineer on the Gas Safe Register — search by name, business or licence number on the official site to confirm they are currently registered.
• Always check the back of the ID card — confirm the category covering the specific appliance being worked on is listed and the card is in date.
• Cross-check the licence number on the card against the register entry to be sure they match.
• Be wary of anyone who cannot or will not produce a card — a genuine registered engineer is happy to show it.

Far from being an inconvenience, customers checking you out is a selling point. Encourage it on your quotes and website — it sets you apart from the illegal fitters who undercut the trade.

Landlord Gas Safety Certificates (CP12)

One of the most common recurring jobs for registered engineers is the annual landlord gas safety check. Under GSIUR, landlords must have every gas appliance and flue in a let property checked for safety every 12 months by a Gas Safe registered engineer, and must give the tenant a copy of the record. That record is the Landlord Gas Safety Record, still widely known by its old form number, CP12.

Only a registered engineer holding the relevant categories can issue a valid certificate. This is steady, predictable, repeat-business work — annual checks fall due on the same date each year, so they are ideal for building a recurring maintenance round. Tracking renewal dates for your landlord clients means you can prompt them before the certificate expires rather than scrambling when a tenancy is at risk.

The Risk of Illegal Gas Work

Unregistered gas work is dangerous and the stakes are life and death. Badly installed or serviced appliances cause gas leaks, fires, explosions and carbon monoxide poisoning. Carbon monoxide is odourless and kills silently — the HSE and Gas Safe run regular campaigns precisely because illegal fitters continue to put lives at risk.

The professional consequences are just as stark. Prosecution under GSIUR can bring unlimited fines and imprisonment. Beyond the courts, illegal or out-of-category work voids your insurance, destroys your reputation the moment it comes to light, and exposes you to civil claims if something goes wrong. Staying properly registered, working only within your categories, and keeping your ACS reassessments current is not bureaucracy — it is what keeps you trading legally and keeps your customers safe.