Quick Answer
A gas safety check (CP12) is an annual inspection of all gas appliances in your home by a Gas Safe registered engineer. It costs £60–£120 and is legally required for landlords every year. Homeowners are strongly advised to have one annually too.
Gas safety is not something to cut corners on. Carbon monoxide and gas leaks kill people in the UK every year — and the majority of incidents are preventable with regular inspection. In 2026, a gas safety check remains one of the most important maintenance tasks for any UK property. This guide explains exactly what a check covers, who must have one, what the CP12 certificate means, and what to do if your appliances fail.
In this guide
What a Gas Safety Check Covers
A gas safety inspection covers every gas appliance, fitting, and pipe in the property. A Gas Safe registered engineer will check:
- Boiler — Burner, heat exchanger, flue, safety controls, gas pressure, and combustion analysis to check for unsafe emissions.
- Gas fires and fireplaces — Pilot light, burner, seals, and flue ventilation.
- Gas cooker and hob — Flame failure devices, burner ignition, seals, and connections.
- Gas pipework — Visual inspection for corrosion, joint integrity, and correct installation throughout the property.
- Flues and ventilation — Ensuring combustion gases can safely escape and adequate fresh air supply exists for appliances to burn correctly.
- Meter and emergency control valve — Checking the meter is accessible and the emergency control valve is operational.
The engineer will also test for gas tightness throughout the pipework — essentially checking for leaks under pressure. Any unsafe or unacceptable situation found will be recorded and classified, and the engineer will advise on immediate action.
Landlord Legal Requirements
Under the Gas Safety (Installation and Use) Regulations 1998, all private landlords in England, Scotland, and Wales are legally required to:
- Have all gas appliances and flues inspected annually by a Gas Safe registered engineer
- Issue a valid CP12 gas safety certificate (Landlord Gas Safety Record) to new tenants before they move in, or to existing tenants within 28 days of the check
- Keep records of all inspections for at least two years
- Ensure all gas appliances are in a safe and working condition throughout the tenancy
Failure to comply is a criminal offence. Local authorities and the Health and Safety Executive (HSE) can prosecute landlords, and penalties include unlimited fines and up to two years' imprisonment. As a landlord, you cannot legally let a property without a valid CP12 in place.
Should Homeowners Have a Gas Safety Check?
Homeowners are not legally required to have annual gas safety checks, but it is strongly recommended — and for very good reason. Boilers and gas appliances deteriorate over time. Flues crack, heat exchangers corrode, and seals fail. These faults aren't always visible or audible — carbon monoxide, the product of incomplete combustion, is odourless and colourless.
An annual boiler service (which includes a safety check) costs £60–£120 and can catch problems before they become dangerous or expensive. Most boiler warranties also require annual servicing to remain valid. Read our detailed guide on gas safety certificate costs for a full breakdown of what you'll pay.
Carbon monoxide alarms are a low-cost safety net — under £25 from any DIY store — and are legally required in all UK rental properties in rooms with a fixed combustion appliance. Homeowners should fit them too.
What Is a CP12 Certificate?
A CP12 (Landlord Gas Safety Record) is the official document issued after a successful gas safety inspection. It contains:
- The address of the property inspected
- Details of every gas appliance checked, including make and model
- The result of each inspection (satisfactory/unsatisfactory)
- Any defects found and remedial action required
- The engineer's name, Gas Safe registration number, and signature
- The date of the inspection and the next due date
Always check that the engineer provides a Gas Safe ID card before they start work. You can verify any Gas Safe registered engineer on the Gas Safe Register website (gassaferegister.co.uk). Never accept a safety check from an unregistered individual — it is illegal for them to carry out gas work and unsafe for you.
To find a qualified engineer and understand what to look for, read our guide on what to look for in a Gas Safe engineer.
What Happens If You Fail a Gas Safety Check?
If the engineer finds a fault, it will be classified according to the Gas Industry Unsafe Situations Procedure (GIUSP):
| Classification | Meaning | Action Required |
|---|---|---|
| Immediately Dangerous (ID) | Immediate risk of injury or death | Appliance disconnected immediately. Cannot be used until repaired. |
| At Risk (AR) | Not immediately dangerous but could become so | Written warning. Strongly advised to repair promptly. |
| Not to Current Standard (NCS) | Does not meet current standards but not dangerous | Noted for information. Repair when practical. |
If your boiler is condemned as Immediately Dangerous, you'll need a replacement. Read our guide on how to choose the right boiler and our full cost guide on how much a new boiler costs in the UK.
Cost of a Gas Safety Check in 2026
| Service | Typical Cost | Notes |
|---|---|---|
| Gas safety check only (1 appliance) | £60 – £90 | Basic CP12 for landlords |
| Gas safety check (whole property) | £80 – £120 | Multiple appliances checked |
| Annual boiler service + safety check | £80 – £150 | Recommended for homeowners |
| Boiler service plan (monthly) | £12 – £25/month | Covers service + breakdown |
| Emergency callout (out of hours) | £80 – £200+ | Fault-finding, no parts |
Frequently Asked Questions
Can I do a gas safety check myself?+
No. By law, all gas safety work in the UK must be carried out by a Gas Safe registered engineer. It is illegal for anyone else — including qualified plumbers without Gas Safe registration — to work on gas appliances or carry out safety inspections.
How long does a gas safety check take?+
A typical gas safety inspection for a property with one boiler takes 30–60 minutes. If you have multiple gas appliances (fires, cooker, boiler), allow 60–90 minutes. The engineer will need access to all gas appliances and the gas meter.
What if my tenant refuses access for the gas safety check?+
Landlords must take all reasonable steps to gain access. Document every attempt in writing. The law provides that landlords have done their duty if they have taken reasonable steps to gain entry — but this is an area where legal advice is worth seeking if access is consistently refused, as your safety obligation remains.
Does a gas safety check cover the meter?+
The engineer will check that the emergency control valve at the meter is accessible and operational, and will carry out a pressure test of pipework up to your appliances. The meter itself is maintained by your gas transporter, not your engineer.
Is a gas safety check the same as a boiler service?+
Not quite. A gas safety check (CP12) is a legal compliance inspection covering all gas appliances and pipework. A boiler service goes further — it includes cleaning the heat exchanger, checking the pump, replacing the filter, and inspecting internal components. Many engineers offer both together at a combined price, which is the best value option.
How do I find a Gas Safe registered engineer near me?+
Use the Gas Safe Register's official search tool at gassaferegister.co.uk, or post your job on GetQuickHelp to be matched with vetted local engineers. Always ask to see the engineer's Gas Safe ID card on arrival — it should show which categories of work they're registered to carry out.
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