Gas Safety Certificates Explained: CP12, Landlords and Homeowners
A gas safety certificate — the CP12, formally a Landlord Gas Safety Record — is a legal document confirming that the gas appliances, pipework and flues at a property have been checked by a Gas Safe registered engineer and found safe.
A gas safety certificate — the CP12, formally a Landlord Gas Safety Record — is a legal document confirming that the gas appliances, pipework and flues at a property have been checked by a Gas Safe registered engineer and found safe. For landlords it is a legal requirement with real consequences for getting it wrong. For homeowners it is not compulsory, but it is often requested when selling or when a warranty or insurer asks for evidence.
Who legally needs one
Landlords letting residential property must have every gas appliance and flue they are responsible for checked every twelve months by a Gas Safe registered engineer, and must give tenants a copy of the record within 28 days of the check, or at the start of a tenancy for new tenants. Records must be kept for two years. Homeowners living in their own property have no legal obligation, though the same annual check is the sensible baseline for safety.
What the engineer actually checks
The certificate is not a service, and the distinction matters. The safety check confirms the appliance is burning correctly, that operating pressure and heat input are within specification, that ventilation is adequate, that the flue is removing products of combustion properly, and that all safety devices work. It looks at pipework and emergency control valve access too. A service goes further, cleaning and inspecting internal components; many landlords sensibly have both done in the same visit.
Timing, and the twelve-month rule
A check can be carried out up to two months before the current certificate expires without losing the original anniversary date, which lets landlords book sensibly rather than at the last minute. Leave it past expiry and the property is non-compliant from that date, regardless of how quickly it is then arranged. Diarising it two months ahead is the simplest way to never be caught out.
Access problems and what a landlord must do
Tenants sometimes will not grant access, and the landlord's duty does not disappear because of it. What is expected is a documented record of reasonable attempts: written requests, repeat appointments offered, explanation of the legal requirement and the safety reason, and escalation in line with the tenancy agreement. Keeping that paper trail is the protection if compliance is ever questioned.
Failed checks and classifications
Where an appliance is unsafe it will be classified — typically as At Risk or Immediately Dangerous — and with your permission it will be disconnected or capped and labelled. That is not an engineer being awkward; it is the required response to an appliance that could harm someone. The record will state what was found, and the appliance cannot go back into use until the fault is corrected and it is re-tested.
Checking your engineer is genuine
Anyone carrying out gas work must be on the Gas Safe Register, and every registered engineer carries an ID card showing their registration number, a photo, an expiry date and the specific categories of work they are qualified for. You can check any number on the Gas Safe Register directly. Ours is registration 554328. Asking to see the card is normal and no legitimate engineer will object to it. It is worth checking the expiry date as well as the number, and glancing at the categories listed on the reverse, because registration is granted per type of appliance and installation rather than as a single blanket permission. If the certificate you are given afterwards does not carry a registration number, a signature and the appliance details, it is not a document you should rely on.
Book a gas safety check
Tell us the property address and how many gas appliances there are, and we will get the safety record sorted.
Questions we get asked
Is a CP12 the same as a boiler service?
No. A safety check confirms the appliance is safe to use; a service inspects and cleans components to keep it working reliably. Many landlords book both together.
Do homeowners need a gas safety certificate?
Not legally, but an annual safety check is strongly advisable, and buyers, warranty providers or insurers may ask for evidence of one.
How early can the annual check be done?
Up to two months before expiry without losing the original anniversary date, which makes booking much easier to manage.
What if a tenant refuses access?
The duty remains, so keep a documented record of written requests and repeated attempts, and follow the escalation route in the tenancy agreement.
What happens if an appliance fails?
It is classified according to the risk and, with permission, disconnected or capped. It cannot be used again until the fault is corrected and it is re-tested.