If you’re a landlord in the UK, a Gas Safety Certificate — commonly called a CP12 — is one of the most important documents you’ll deal with each year. It proves that a Gas Safe registered engineer has inspected the gas appliances in your rental property and confirmed they’re safe to use.
At Boilers2go, we often explain that a CP12 certificate protects tenants, protects property, and protects landlords legally — which is why it sits alongside EPC certificates and electrical safety reports as essential compliance paperwork.
Put simply, gas safety checks keep heating systems safe and homes protected.
What a CP12 Certificate Actually Is
A CP12 Gas Safety Certificate is the official record showing gas appliances have been inspected and tested for safety in a rental property. When an engineer checks a boiler, cooker, or gas fire, they’re confirming the appliance is burning gas correctly, operating at the right pressure, and safely removing combustion gases through the flue.
In everyday terms, the certificate confirms that gas appliances are working safely, flues are removing fumes correctly, and pipework is sound.
The name “CP12” comes from an older CORGI inspection form, but the meaning hasn’t changed — a CP12 certificate confirms annual gas safety compliance in rented homes.
The certificate is always:
- Issued by a Gas Safe registered engineer
- Valid for 12 months
- Required for rental properties with gas appliances
The Legal Side of Gas Safety
Gas safety in rental properties is governed by the Gas Safety (Installation and Use) Regulations 1998, which clearly state that landlords must arrange annual gas safety checks for appliances they provide.
In practice, this means a landlord must make sure a qualified engineer inspects boilers, gas fires, cookers, flues, and pipework once every year.
Landlords must also provide tenants with a copy of the certificate within 28 days and keep records for at least two years.
These rules exist for one simple reason: unsafe gas appliances can produce carbon monoxide, and carbon monoxide exposure can be fatal. Regular inspection ensures appliances burn gas properly and ventilation removes fumes safely from the property.
From our experience at Boilers2go, landlords who stay on top of annual checks rarely run into safety or compliance issues later.
What Happens During a CP12 Inspection?
When a Boilers2go engineer carries out a gas safety check, the goal is straightforward — confirm that every gas appliance operates safely under normal conditions.
During the visit, the engineer checks that:
- Gas appliances burn fuel correctly
- Operating pressure matches manufacturer specifications
- Flues remove combustion gases safely
- Ventilation allows safe combustion
- Pipework is secure and leak-free
If an appliance is unsafe, it will be classified and isolated if necessary. That’s because engineers must prioritise safety over keeping appliances running.
A CP12 inspection isn’t just a formality — it’s a practical safety check designed to prevent gas leaks, overheating appliances, and carbon monoxide risks.
What You’ll See on the Certificate
A CP12 certificate provides a clear safety record of the inspection. It shows who carried out the check, what was inspected, and whether appliances were safe at the time of testing.
Most certificates include property details, landlord information, engineer credentials, inspection dates, appliance locations, and safety test results.
Digital certificates are now common, which makes sharing records with tenants or managing agents much easier.
Who Needs a CP12?
For rental properties, responsibility is simple — the landlord is responsible for gas safety compliance.
Private landlords, housing associations, and HMO property owners must all arrange annual gas safety checks where gas appliances are installed.
Tenants don’t arrange inspections, but they must receive a copy of the certificate.
Homeowners living in their own property aren’t legally required to have a CP12, but many still book annual checks for peace of mind — particularly if the boiler is older.
Even when a managing agent is involved, legal responsibility for gas safety still sits with the landlord unless formally transferred.
CP12 Certificate Cost
A landlord gas safety certificate is usually one of the more affordable compliance checks.
Across most of the UK, a CP12 inspection typically costs between £40 and £100, depending on the number of appliances and location.
The process is simple: book a Gas Safe engineer, arrange the inspection, receive the certificate, and provide a copy to tenants.
At Boilers2go, we often remind landlords that annual servicing and safety checks help appliances last longer, reduce breakdown risk, and keep heating systems running efficiently.
Boiler Service + CP12 Bundle (Recommended for Landlords)
For most landlords, the simplest way to stay compliant and keep heating systems reliable is to book a boiler service and CP12 gas safety check together.
A boiler service improves performance and reliability, while a CP12 inspection confirms appliances are safe to use. When done at the same visit, the engineer can fully check the heating system in one appointment — saving time, reducing call-out costs, and helping prevent future breakdowns.
At Boilers2go, we regularly see that annual servicing helps boilers run more efficiently, reduces wear on key components, and lowers the risk of emergency repairs, while the CP12 provides the legal safety record landlords need.
In practical terms, the visit usually includes:
- A boiler service check following manufacturer guidelines
- Gas safety checks on landlord-supplied appliances
- Flue and combustion safety testing
- Pipework and ventilation checks
- Issuing the CP12 certificate after inspection
Booking both together means your boiler is maintained, your property stays compliant, and your tenants remain protected — all in one visit.
Why the CP12 Really Matters
It’s easy to think of a CP12 certificate as just another compliance task, but it’s much more than that.
A gas safety check prevents dangerous faults, confirms appliances are burning gas correctly, and ensures fumes leave the property safely. That’s what keeps tenants safe and heating systems reliable.
For landlords, the certificate also proves that reasonable steps have been taken to maintain gas safety in the property, which can be crucial for insurance and legal protection.
At Boilers2go, we always say the same thing: a CP12 certificate isn’t just paperwork — it’s proof that a property’s heating and gas appliances are safe for another year.
With years of experience in boilers and home improvements in general, Myles Robinson is a passionate advocate for making home heating simpler, safer, and more affordable for households across the UK. With years of experience in the heating industry, Myles combines hands-on knowledge with a focus on customer-first service, helping homeowners choose the right boiler, understand their systems, and keep their heating running efficiently all year round. His articles break down complex topics into clear, practical advice you can trust.