Gas Safe Register: How to Check Your Engineer

When you are preparing your property for sale, one of the most important steps is ensuring that your gas appliances are safe and that you have the documentation to prove it. A gas safety certificate gives buyers and their solicitors confidence that the gas installation in your home has been professionally inspected. But that certificate is only as good as the engineer who issued it.

If the engineer who carried out your gas safety check was not properly registered with Gas Safe Register, the certificate they issued is worthless. Worse, you may have unsafe gas work in your property without knowing it. This guide walks you through how to verify an engineer's credentials, what to look for on their ID card, and what records to keep so your property sale runs smoothly.

What is the Gas Safe Register?

Gas Safe Register is the official list of gas engineers who are legally permitted to work on gas appliances in Great Britain, the Isle of Man, and Guernsey. It is managed by Capita Gas Registration and Trading Ltd under a contract with the Health and Safety Executive (HSE).

Gas Safe Register replaced CORGI (Council for Registered Gas Installers) on 1 April 2009. While CORGI had been the recognised registration body since 1991, it is no longer the legal regulator. Any engineer who was previously CORGI-registered had to re-register with Gas Safe Register to continue carrying out gas work legally.

The Gas Safety (Installation and Use) Regulations 1998 make it a criminal offence for anyone who is not on the Gas Safe Register to carry out gas work. This includes installation, maintenance, servicing, repair, disconnection, and safety checks. It is also an offence for a property owner to knowingly allow an unregistered person to carry out gas work on their premises.

Why checking matters when you are selling

For most homeowners, verifying a gas engineer's registration is a sensible safety precaution. But when you are selling your property, it becomes essential for a different reason: the documentation trail.

When your solicitor assembles the property certificate pack for the buyer, they will include your gas safety record (CP12) and any boiler service reports. The buyer's solicitor will review these documents as part of their due diligence. If they discover that a certificate was issued by an engineer whose registration was expired or invalid at the time of the inspection, they will raise it as a serious enquiry.

In the worst case, this means you need to arrange a completely new gas safety check at short notice, which adds delay and cost to the transaction. It can also undermine buyer confidence in the property's overall maintenance history. By taking two minutes to verify your engineer's credentials before the appointment, you avoid this risk entirely.

How to check an engineer's Gas Safe registration

There are three ways to verify that a gas engineer is properly registered. You should use at least one of these methods before allowing any gas work to take place.

1. Check online at GasSafeRegister.co.uk

The quickest method is to visit the Gas Safe Register website and use their “Find an engineer” tool. You can search by:

• Registration number — the seven-digit number on the front of the engineer's ID card
• Business name — useful if you are hiring through a company rather than an individual
• Postcode — to find registered engineers in your area

The search results will confirm the engineer's name, their employing business, whether their registration is current, and the specific categories of gas work they are qualified to carry out. A current registration means the engineer is legally authorised to perform gas work on the date you check.

2. Call the Gas Safe helpline

You can call 0800 408 5500 (free from UK landlines and mobiles) to verify an engineer's registration. The helpline is available Monday to Friday, 8am to 6pm. An operator will confirm the engineer's registration status, their qualified appliance categories, and their card expiry date. This is particularly useful if you do not have internet access or prefer to speak to someone directly.

3. Check the Gas Safe ID card in person

Every Gas Safe registered engineer is required to carry their ID card when carrying out gas work. You should ask to see the card before any work begins. Here is what to look for:

Pay particular attention to the expiry date on the front and the appliance categories on the back. If the card has expired, the engineer is not currently registered and must not carry out gas work. If the specific appliance you need inspecting is not listed on the back of the card, the engineer is not qualified to work on it, even if they are registered for other types of gas work.

Understanding appliance categories

Gas Safe registration is not a single, catch-all qualification. Engineers are registered for specific appliance categories, each with its own code. The most common categories you will encounter in residential properties are:

An engineer registered for CCN1 (boilers) can inspect and service your central heating boiler, but cannot legally work on your gas fire unless they also hold the HTR1 category. When arranging a full gas safety check that covers all appliances in your home, make sure the engineer you book holds the categories for every appliance that needs inspecting. A single engineer who holds all the relevant categories is the most efficient option, but some properties with unusual appliances (such as LPG systems or commercial-grade ranges) may require a specialist.

What documentation to keep for your sale

When you are selling your property, the gas safety documentation you provide forms part of your property certificate pack. Keeping organised records throughout your ownership makes the conveyancing process significantly smoother. Here is what to retain:

Gas safety record (CP12)

This is the certificate issued after each gas safety check. It records the engineer's name and registration number, the date of inspection, each appliance checked, and whether it passed or failed. Keep every CP12 you receive, not just the most recent one. A history of annual checks demonstrates consistent maintenance.

Boiler service reports

A boiler service record is separate from a gas safety certificate. While a gas safety check confirms that appliances are safe, a boiler service is a more thorough maintenance procedure. Buyers place significant value on seeing both types of documentation together.

Installation certificates

If your boiler or any other gas appliance was installed or replaced during your ownership, you should have a Building Regulations compliance certificate (sometimes called a Building Control Completion Certificate). Gas boiler installations must be notified to the local authority building control department, and the installer should have done this on your behalf through the Gas Safe notification scheme. Keep these certificates alongside your CP12 records.

Repair invoices and correspondence

Any repair work carried out on gas appliances should be documented with an invoice showing the engineer's Gas Safe registration number, the date of the work, what was done, and what parts were replaced. This creates a full audit trail that supports the information you provide on the TA6 Property Information Form.

Red flags to watch for

When hiring a gas engineer, be alert to the following warning signs that suggest someone may not be properly registered or qualified:

• Refuses to show their ID card. A legitimate Gas Safe registered engineer will have their card readily available and will not object to you checking it. Any reluctance is a serious red flag.
• Expired ID card. If the expiry date on the front of the card has passed, the engineer is not currently registered, regardless of what they may tell you. An expired card means they cannot legally carry out gas work.
• Wrong appliance categories. If the work you need is not listed on the back of the card, the engineer is not qualified for that specific task. Do not accept assurances that it “will be fine” — appliance categories exist for safety reasons.
• No written documentation. After completing a gas safety check, a registered engineer must provide you with a gas safety record (CP12). If an engineer completes a check but does not issue paperwork, the work has not been properly documented and the certificate cannot be relied upon for your sale.
• Unusually low prices. While gas safety check prices vary by region, quotes that are significantly below the market rate of £60 to £120 may indicate an unregistered operator. Legitimate engineers have ongoing costs for registration, training, insurance, and equipment.
• Cash only, no receipt. Professional gas engineers will provide a proper invoice or receipt. An insistence on cash with no paperwork is a warning sign of unregistered work.

What to do if you suspect illegal gas work

If you believe gas work has been carried out in your property by an unregistered person — whether by a previous owner or a tradesperson you hired — you should take immediate action:

1. Do not use the affected appliance until it has been inspected by a properly registered Gas Safe engineer.
2. Report the unregistered work to Gas Safe Register on 0800 408 5500 or through their website, or contact the Health and Safety Executive (HSE).
3. Arrange a safety inspection by a Gas Safe registered engineer as soon as possible. They will assess whether the installation is safe or whether remedial work is needed.
4. Keep all documentation from the inspection, including any findings about non-compliant work. This information will be relevant if you are selling the property and need to disclose the history of gas work on the TA6 form.

Discovering illegal gas work before you list your property is always better than having it surface during the sale. A buyer's surveyor or the buyer's solicitor may identify non-compliant work, and at that point you will be dealing with remediation under time pressure and with a nervous buyer.

Gas Safe Register and the TA6 form

When completing the TA6 Property Information Form, you will be asked about the gas supply, heating system, and maintenance history. Being able to provide gas safety certificates that were issued by verified, registered engineers strengthens your disclosure considerably.

You should attach copies of your most recent gas safety record (CP12) and boiler service report to the TA6. If the buyer's solicitor can see that the certificates include valid Gas Safe registration numbers, they are far less likely to raise additional enquiries about gas safety. This reduces the back-and-forth that can add weeks to a transaction.

Conversely, if you provide a certificate that the buyer's solicitor cannot verify against the Gas Safe Register — because the registration number is invalid, expired, or missing — expect follow-up questions and a potential requirement for a fresh inspection before the sale can proceed.

Seller's checklist: Gas Safe verification

Use this checklist to make sure your gas documentation is in order before you list your property:

1. Before booking a gas safety check, verify the engineer's registration at GasSafeRegister.co.uk or by calling 0800 408 5500
2. On the day, ask to see both sides of the engineer's Gas Safe ID card and check the expiry date
3. Confirm the back of the card includes the appliance categories for all gas appliances in your property
4. After the inspection, check you have received a completed gas safety record (CP12) with the engineer's name and registration number
5. Keep the CP12 alongside any boiler service reports, installation certificates, and repair invoices
6. Provide all gas documentation to your solicitor for inclusion in the property certificate pack
7. If you discover any previously completed gas work by unregistered engineers, arrange a fresh inspection and report the illegal work

Sources

• Gas Safe Register — GasSafeRegister.co.uk
• Health and Safety Executive (HSE) — Gas safety in the home, hse.gov.uk
• Gas Safety (Installation and Use) Regulations 1998 — legislation.gov.uk
• GOV.UK — Gas Safe Register: check an engineer or business
• Law Society — Property Information Form (TA6), 4th edition
• Building Regulations 2010, Part J (Combustion appliances and fuel storage systems) — legislation.gov.uk

Frequently asked questions