Gas Safety Certificate When Selling a House: Do You Need One?
Whether sellers need a gas safety certificate, what buyers will expect, and how to get one from a Gas Safe registered engineer.
What you need to know
Owner-occupier sellers in England and Wales are not legally required to provide a gas safety certificate when selling their home. However, buyers, solicitors, and mortgage lenders increasingly expect one. Getting a gas safety check from a Gas Safe registered engineer before you list can prevent delays, reduce buyer enquiries, and give confidence that your gas appliances are safe.
- Owner-occupier sellers have no legal obligation to provide a gas safety certificate, but landlords must provide a valid CP12 to buyers.
- A gas safety check costs £60 to £120 and is carried out by a Gas Safe registered engineer. It covers all gas appliances, pipework, and flues.
- Buyers' solicitors routinely ask about gas safety on the TA6 Property Information Form, and providing a certificate proactively reduces follow-up enquiries.
- Boiler service records alongside a gas safety certificate give buyers the strongest reassurance about the condition of the heating system.
- Gas issues flagged by a surveyor can lead to mortgage retentions or conditions, delaying your sale — a proactive check avoids this risk.
Pine handles the legal prep so you don't have to.
Check your sale readinessNo, you do not legally need a gas safety certificate to sell your house if you are an owner-occupier in England or Wales. The legal requirement for annual gas safety checks applies only to landlords under the Gas Safety (Installation and Use) Regulations 1998. However, that does not mean you should skip it. Buyers, their solicitors, and their mortgage lenders will all want to know that the gas appliances in your home are safe, and failing to provide evidence of this can slow down or even derail your sale. Unlike an Energy Performance Certificate, a gas safety certificate is not required before you can market your property — but providing one proactively is one of the smartest moves you can make.
This guide explains the legal position on gas safety certificates for sellers, what buyers and solicitors will expect, how to get a certificate, what it costs, and why providing one proactively is one of the simplest things you can do to keep your sale moving.
The legal position: who needs a gas safety certificate?
The legal requirements around gas safety certificates depend on whether you are an owner-occupier or a landlord.
Owner-occupiers (selling your own home)
If you live in the property you are selling, there is no legal requirement to obtain a gas safety certificate before or during the sale. The Gas Safety (Installation and Use) Regulations 1998, enforced by the Health and Safety Executive (HSE), place duties on landlords but not on homeowners selling their own property. You will not be breaking any law by selling without one.
However, the absence of a legal requirement does not mean buyers and their solicitors will not ask for one. In practice, most conveyancing solicitors will raise enquiries about gas safety as part of the standard conveyancing process, and not having a certificate to provide can create delays. For an overview of all the paperwork you need to prepare, see our guide on documents needed to sell a house.
Landlords (selling a tenanted or rental property)
If you are a landlord selling a property that has been rented out, you must have a valid gas safety certificate (CP12) in place. Under Regulation 36 of the Gas Safety (Installation and Use) Regulations 1998, landlords are required to arrange an annual gas safety check by a Gas Safe registered engineer and to provide a copy of the gas safety record to tenants within 28 days of the check and to new tenants before they move in. When selling, your buyer's solicitor will request a copy of the current CP12 as part of the conveyancing enquiries, and any buyer purchasing as an investment will expect the gas safety records to be in order.
What is a gas safety certificate (CP12)?
A gas safety certificate — formally known as a Landlord Gas Safety Record or CP12 — is a document issued by a Gas Safe registered engineer after inspecting the gas appliances, pipework, and flues in a property. The name CP12 is a legacy from the old CORGI registration system, but the term remains widely used in the industry.
The certificate records:
- The name and Gas Safe registration number of the engineer who carried out the inspection
- The date of the inspection and the date of the next check due
- The address of the property inspected
- Each gas appliance checked, including its type, make, model, and location
- The results of safety checks on each appliance, including flue flow, gas pressure, and combustion readings
- Whether each appliance has passed or failed the inspection
- Any defects found and any remedial action required
A gas safety certificate is valid for 12 months from the date of issue. For a sale, the certificate should ideally be current at the point the buyer's solicitor requests it.
What buyers and solicitors expect
Even though owner-occupier sellers are not legally required to provide a gas safety certificate, the practical reality is that buyers and their solicitors will ask about gas safety. Here is where gas safety comes up during the sale process:
The TA6 Property Information Form
The TA6 Property Information Form is the standard disclosure form completed by sellers in England and Wales. Section 7 covers services and utilities, and your solicitor will ask you to confirm what gas appliances are in the property, when they were last serviced, and whether you are aware of any defects. If you have a gas safety certificate and boiler service records, you can attach copies to the TA6 to support your answers. If you do not have them, the buyer's solicitor may raise additional enquiries asking you to provide evidence of gas safety.
The buyer's survey
When the buyer arranges a homebuyer's report or a building survey, the surveyor will visually inspect the boiler and any visible gas pipework. Surveyors are not Gas Safe registered (unless they happen to hold that qualification separately), so they cannot test gas appliances. However, they will note the age and apparent condition of the boiler, flag any visible concerns, and recommend that the buyer arranges a full gas safety inspection if they have any doubts. If the surveyor recommends further investigation, the buyer's mortgage lender may impose a condition requiring a satisfactory gas safety check before releasing the mortgage funds.
Mortgage lender requirements
Most mortgage lenders do not routinely require a gas safety certificate as a condition of lending on a standard residential purchase. However, if the surveyor flags concerns or if the property has an old boiler, the lender may impose a retention — withholding part of the mortgage funds until a satisfactory gas safety check is provided. This can delay completion and cause frustration for both parties. Providing a certificate upfront removes this risk entirely.
Gas safety certificate vs. boiler service: what is the difference?
Sellers often confuse a gas safety check with a boiler service. While they are related and often carried out at the same appointment, they serve different purposes:
| Gas safety check | Boiler service |
|---|---|
| Visual and operational safety inspection | Full maintenance service |
| Checks all gas appliances, flues, and visible pipework | Focuses on the boiler specifically |
| Confirms appliances are safe to use | Cleans and maintains internal components |
| Issues a CP12 gas safety record | Issues a boiler service report |
| Typically costs £60 – £90 | Typically costs £70 – £120 |
| Combined check and service: £90 – £150 | Combined check and service: £90 – £150 |
For the best results when selling, arrange both a gas safety check and a boiler service at the same appointment. This gives buyers a current gas safety certificate and evidence that the boiler has been properly maintained. Most Gas Safe registered engineers offer a combined service, and it provides better value than booking them separately.
How to get a gas safety certificate
Getting a gas safety certificate is straightforward, but you must use the right engineer. Here is what you need to know:
Use a Gas Safe registered engineer
It is illegal for anyone who is not registered with Gas Safe Register to carry out work on gas appliances, including safety checks. Gas Safe Register replaced CORGI as the official gas registration body in Great Britain in 2009 and is the only body approved by the HSE to register gas engineers. You can verify an engineer's registration at GasSafeRegister.co.uk or by calling 0800 408 5500. Every registered engineer carries an ID card showing their registration number, the types of gas work they are qualified to carry out, and the card's expiry date.
What to expect during the inspection
A gas safety inspection typically takes 30 to 60 minutes, depending on how many gas appliances are in the property. The engineer will:
- Check each gas appliance for safe operation and correct gas pressure
- Test the flue or chimney serving each appliance to ensure combustion products are being safely discharged
- Inspect visible gas pipework for signs of leaks, corrosion, or damage
- Check that there is adequate ventilation for each appliance
- Test safety devices such as flame failure mechanisms
- Take combustion readings to check that each appliance is burning gas safely and efficiently
At the end of the inspection, the engineer will issue a gas safety record (CP12) listing each appliance and whether it has passed or failed.
Cost
A gas safety check typically costs £60 to £120, depending on your location and the number of gas appliances. Properties with multiple gas appliances (boiler, hob, fire, water heater) will be at the higher end. A combined gas safety check and boiler service usually costs £90 to £150. Prices vary across the UK, with London and the South East tending to be higher.
Common gas safety issues that affect property sales
Certain gas-related issues come up regularly during property transactions and can cause delays or complications if not dealt with early:
- Old or inefficient boilers. Boilers over 15 years old are more likely to fail a gas safety check or raise concerns on the buyer's survey. While an old boiler does not prevent a sale, it may prompt the buyer to negotiate on price or request a replacement as a condition of proceeding.
- No service history. If you cannot produce any boiler service records or gas safety certificates, the buyer's solicitor may raise enquiries and the buyer may factor the uncertainty into their offer. Keeping records is one of the simplest ways to smooth the sale process.
- Uncapped or poorly maintained gas fires. Old gas fires, particularly open-flued models, are a common source of failures on gas safety inspections. If you have a gas fire that is no longer in use, having it properly disconnected and capped off before the sale is advisable.
- Non-compliant gas work. DIY gas work or work carried out by unregistered fitters is illegal and dangerous. If a Gas Safe engineer identifies non-compliant work during an inspection, it must be rectified before a certificate can be issued. This is something you are much better off discovering and fixing before you list your property rather than having it emerge during the buyer's survey.
- Carbon monoxide alarm absence. While not currently a legal requirement for owner-occupiers in all rooms, the Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022 require landlords to install carbon monoxide alarms in rooms with fixed combustion appliances (excluding gas cookers). Buyers increasingly expect carbon monoxide alarms to be present, especially near gas boilers and fires.
The TA6 form and gas safety disclosure
The TA6 Property Information Form is one of the key documents needed to sell a house. It is your opportunity to disclose information about the property honestly and completely, and gas safety is an important part of this.
In the services section of the TA6, you will be asked to provide details about the gas supply, heating system, and hot water system. You should include:
- Whether the property is connected to mains gas
- The type and age of the boiler
- When the boiler was last serviced
- Whether you have any gas safety certificates or service records
- Any known defects or issues with the gas installation
Being thorough and honest on the TA6 is essential. Under the seller's duty of disclosure, providing inaccurate or incomplete information about the condition of gas appliances could expose you to a claim from the buyer after completion. Attaching a current gas safety certificate to the TA6 is the clearest way to demonstrate that you have provided accurate information about the safety of your gas installation.
Benefits of providing a gas safety certificate proactively
While you are not legally obliged to provide a gas safety certificate as an owner-occupier seller, there are compelling practical reasons to do so:
- Fewer buyer enquiries. If a current gas safety certificate is included in your draft contract pack, the buyer's solicitor has one less thing to raise during conveyancing enquiries. Each round of unnecessary enquiries can add one to two weeks to the timeline.
- Avoids mortgage retention risks. If the buyer's surveyor raises concerns about gas safety, the mortgage lender may withhold funds until a satisfactory check is provided. Having a certificate already in hand eliminates this risk.
- Builds buyer confidence. A gas safety certificate signals that you have maintained your property responsibly. This is particularly valuable alongside an electrical safety certificate and a valid EPC, which together present a comprehensive picture of the property's safety and efficiency.
- Catches problems early. If there is an issue with a gas appliance, it is far better to discover it before you list than to have it emerge during the transaction. Fixing a problem on your own terms and timeline is always preferable to dealing with it under the pressure of an active sale.
- Low cost, high return. At £60 to £120, a gas safety check is one of the cheapest steps you can take during sale preparation, and it can save weeks of delay and thousands of pounds in renegotiated offers.
Gas Safe Register: what you need to know
Gas Safe Register is the official register of gas engineers in Great Britain, the Isle of Man, and Guernsey. It was established in 2009 to replace CORGI and is overseen by the Health and Safety Executive (HSE). Only engineers registered with Gas Safe Register are legally allowed to carry out gas work, including safety checks, repairs, installations, and servicing.
When hiring a gas engineer for your gas safety check, you should:
- Ask to see the engineer's Gas Safe ID card before they begin work
- Check the back of the card to confirm they are qualified for the type of gas work you need (the card lists specific appliance categories)
- Verify their registration online at GasSafeRegister.co.uk or by calling 0800 408 5500
- Report any suspected unregistered gas work to Gas Safe Register or the HSE
Using an unregistered engineer is not only dangerous but also means any certificate they issue will not be valid. It is a criminal offence for an unregistered person to carry out gas work, and an offence for a property owner to knowingly allow unregistered gas work to take place.
Seller's checklist for gas safety
Use this checklist to make sure gas safety does not become a stumbling block in your sale:
- Book a gas safety check with a Gas Safe registered engineer before you list your property
- Consider combining the gas safety check with a boiler service for better value and stronger documentation
- Gather any existing boiler service records and previous gas safety certificates
- If any gas appliances fail the inspection, arrange repairs or replacement promptly
- Have unused gas appliances properly disconnected and capped off by a Gas Safe registered engineer
- Complete the services section of the TA6 form accurately and attach copies of the gas safety certificate and service records
- Ensure carbon monoxide alarms are fitted near all gas appliances
- Provide the gas safety certificate to your solicitor so it can be included in the draft contract pack sent to the buyer's side
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 — Renting out your property: gas safety
- Law Society — Property Information Form (TA6), 4th edition
- Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022 — legislation.gov.uk
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Frequently asked questions
Do I legally need a gas safety certificate to sell my house?
If you are an owner-occupier selling your home, there is no legal requirement under English or Welsh law to obtain a gas safety certificate before selling. The Gas Safety (Installation and Use) Regulations 1998 impose a duty on landlords to arrange annual gas safety checks, but this obligation does not extend to homeowners selling a property they have been living in. That said, providing one voluntarily is strongly recommended because it reassures buyers and their solicitors that the gas appliances are safe, and it can prevent delays during the conveyancing process.
What is the difference between a gas safety certificate and a CP12?
A gas safety certificate and a CP12 are the same document. CP12 is the industry name for the Landlord Gas Safety Record, which is the certificate issued by a Gas Safe registered engineer after completing a gas safety inspection. The term CP12 comes from the old CORGI (Council for Registered Gas Installers) certification numbering system. Whether it is called a gas safety certificate, a gas safety record, or a CP12, it confirms that all gas appliances, flues, and pipework in the property have been inspected and are safe to use at the time of the check.
How much does a gas safety certificate cost?
A gas safety check typically costs between £60 and £120, depending on your location and the number of gas appliances in the property. A property with a single gas boiler will usually be at the lower end, while a home with a boiler, gas hob, gas fire, and additional gas appliances will cost more because each appliance must be individually inspected. Some engineers offer a combined gas safety check and boiler service for around £90 to £150, which provides better value and gives buyers even more confidence in the condition of the heating system.
Is a gas safety certificate the same as a boiler service?
No, a gas safety check and a boiler service are different things, although they are often carried out at the same time. A gas safety check is a visual and operational inspection to confirm that gas appliances are safe to use — it covers flue integrity, gas pressure, ventilation, and combustion readings. A boiler service is a more thorough maintenance procedure that includes cleaning internal components, checking seals, inspecting the heat exchanger, and ensuring the boiler is running efficiently. Both are carried out by Gas Safe registered engineers, and providing records of both to buyers gives the strongest reassurance.
What does a Gas Safe engineer check during an inspection?
During a gas safety inspection, a Gas Safe registered engineer will check each gas appliance for safe operation, correct gas pressure, and proper combustion. They inspect all visible gas pipework for leaks, corrosion, or damage. They examine the flue or chimney serving each appliance to ensure combustion gases are being safely discharged outside the property. They also check that there is adequate ventilation for each appliance and test safety devices such as flame failure mechanisms. The engineer records the results on a gas safety record (CP12), noting each appliance, its location, and whether it has passed or failed the inspection.
What happens if a gas appliance fails the safety check?
If a gas appliance fails the safety check, the Gas Safe registered engineer will classify it as either At Risk or Immediately Dangerous. An At Risk appliance is one that does not meet current safety standards but is not an immediate threat — the engineer will advise you to get it repaired or replaced. An Immediately Dangerous appliance poses an imminent risk to life, and the engineer is required to disconnect it and attach a warning label. In either case, the appliance cannot be used until the fault is repaired by a qualified engineer and a satisfactory follow-up check is completed.
Do I need a gas safety certificate if my property has no gas supply?
No, if your property has no gas supply and no gas appliances, you do not need a gas safety certificate. You should confirm this clearly on the TA6 Property Information Form when answering questions about utilities and services. If a gas supply was previously connected but has since been capped off and disconnected, it is worth mentioning this on the TA6 as well. Buyers and their solicitors will want to understand whether any gas infrastructure remains in the property, even if it is no longer in use, so providing clear information avoids unnecessary enquiries.
How long is a gas safety certificate valid for?
A gas safety certificate is valid for 12 months from the date it was issued. If your certificate was issued more than 12 months before your buyer's solicitor requests it, they may ask you to obtain a new one. For the strongest position during a sale, it is best to arrange a gas safety check within the three months before you list your property. This ensures the certificate will still be valid throughout the typical conveyancing timeline of 12 to 16 weeks. Landlords are required by law to renew their certificate annually, but owner-occupiers have no such legal obligation.
Will my buyer's mortgage lender require a gas safety certificate?
Most mortgage lenders do not make a gas safety certificate a formal condition of lending for standard residential purchases. However, if the surveyor's report flags concerns about the gas installation — such as an old boiler, visible signs of poor maintenance, or a recommendation for further investigation — the lender may impose a retention or require a satisfactory gas safety check before releasing the full mortgage funds. Providing a valid gas safety certificate proactively can prevent this scenario and avoid delays at a critical stage of the transaction.
Can I sell a house with an old or condemned boiler?
Yes, you can sell a house with an old or even condemned boiler, but you must disclose its condition honestly on the TA6 Property Information Form. If a Gas Safe engineer has classified the boiler as At Risk or Immediately Dangerous, you should include this information along with any documentation from the engineer. Buyers will factor the cost of replacement into their offer, so expect negotiations on price. Being upfront about a faulty boiler is always better than having it discovered during the buyer's survey, which can undermine trust and lead to the sale falling through.
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