Gas Safety Certificate (CP12)
A gas safety certificate, formally called a Gas Safety Record and widely known as a CP12, is the written confirmation from a Gas Safe registered engineer that gas appliances, fittings, flues, and associated pipework in a rented property have been inspected and were safe at the time of check. The duty to carry out annual gas safety checks and provide tenants with the record is set out in regulation 36 of the Gas Safety (Installation and Use) Regulations 1998 (SI 1998/2451), enforced by the Health and Safety Executive (HSE) and local housing authorities.
The name CP12 originates from the old CORGI registration scheme, under which gas engineers were registered before Gas Safe Register replaced it in April 2009. The document itself has always been the Gas Safety Record; CP12 is the industry shorthand that has persisted.
Which properties require one
The obligation applies to every residential rental property that has gas appliances, flues, pipework, or a gas supply, regardless of whether the appliances are used or are the landlord's own. Properties with no gas installation at all are exempt. The duty rests on the landlord, though a managing agent can be contractually delegated responsibility for arranging checks. In HMOs, the check covers all gas appliances in the common parts and individual rooms.
What the engineer checks
A Gas Safe engineer carries out a systematic inspection of each gas appliance, typically the boiler, gas hob, gas fire, and any other fixed gas appliances, along with the pipework, flues, ventilation, and gas pressure. The engineer tests whether each appliance is burning correctly, whether flues are clear and drawing properly, whether there are any gas leaks, and whether safety devices operate as intended. Appliances that are found to be unsafe are classified as either "At Risk" or "Immediately Dangerous". An Immediately Dangerous appliance must be disconnected or capped off on the spot; an At Risk appliance can remain in use temporarily but requires prompt remedial action. The landlord is responsible for arranging and funding any repairs identified.
What must appear on the certificate
Regulation 36(3) of the Gas Safety (Installation and Use) Regulations 1998 specifies exactly what a valid gas safety record must contain. A certificate missing any of these items is non-compliant and creates the same legal exposure as having no certificate at all. The required information is: the date of the inspection; the address of the property; the name and address of the landlord or their agent; the name and Gas Safe registration number of the engineer; a description and location of each appliance or flue inspected; the results of the inspection; any defects identified and action taken or required; and confirmation that the check has been carried out. Always verify these details when you receive the certificate, errors by the engineer, particularly omission of the landlord's address, are common and have caused possession claims to fail.
Delivery and record-keeping obligations
A copy of the current gas safety record must be given to new tenants before they move in, and to existing tenants within 28 days of each annual check being completed. The record must be retained for at least two years. If a prospective tenant asks to see the current record before signing, the landlord must provide it. These obligations apply even if the tenancy agreement is unsigned or the tenancy has not yet started.
Gas safety checks are separate from boiler servicing, which is a maintenance exercise rather than a legal safety inspection; many landlords combine both in a single annual visit for efficiency, but the gas safety record and any service documentation are separate documents.
The early renewal rule
Landlords can arrange the annual gas safety check up to two months before the expiry of the current certificate and retain the original expiry date as the next renewal date, a provision analogous to the MOT early renewal rule for vehicles. This allows landlords to book ahead and avoid last-minute gaps without shortening the 12-month interval. The check cannot be done more than two months early without losing the renewal date alignment.
Penalties for non-compliance
Failure to carry out a gas safety check, provide the record to tenants, or retain the documentation is a criminal offence under the Gas Safety (Installation and Use) Regulations 1998. Conviction carries a fine of up to £6,000 per offence, with each gas appliance potentially constituting a separate offence. Local housing authorities can also issue civil penalties of up to £30,000. In cases where a gas incident causes injury or death in a property without a valid certificate, the landlord may face prosecution under the Health and Safety at Work etc. Act 1974, with unlimited fines and potential custodial sentences. Absence of a valid gas safety certificate also typically invalidates landlord insurance cover for gas-related incidents.
Under the Renters' Rights Act, the gas safety record is one of the compliance documents that courts consider when landlords apply for a possession order. A landlord who has not maintained a continuous chain of valid certificates may find possession claims challenged, and courts have discretion to take ongoing regulatory failures into account when deciding whether to grant possession. This applies to all grounds-based possession claims under Section 8, previously the risk was primarily linked to Section 21, which was abolished on 1 May 2026.
Carbon monoxide risks identified during a gas safety check should also prompt landlords to confirm that carbon monoxide alarm regulations are met across the property.
A valid gas safety record also forms part of a landlord's broader obligation to keep a property fit for human habitation. August's compliance checklist and smart reminders track gas safety certificate renewal dates automatically, alerting landlords before expiry and storing the record alongside other compliance documents.
What to do if a tenant refuses access
A landlord cannot force entry to carry out a gas safety check, but must document all reasonable attempts to arrange access. Written requests by letter, email, and text, along with a clear record of dates, responses, and any appointments offered and refused, are essential evidence of compliance if enforcement action follows. A landlord who has made and documented reasonable efforts is in a far stronger position than one who has allowed the check to lapse without evidence of having tried. Courts and councils take a proportionate view of genuine access difficulties, but only where the documentary trail clearly demonstrates them.
For the complete practical guide, covering inspection checklists, how to manage tenant access, renewal timing, and compliant record storage, see Gas Safety Certificates: The Complete UK Landlord Guide.
Frequently asked questions
Is a gas safety certificate the same as a CP12?
Yes. CP12 is an industry shorthand for the Landlord Gas Safety Record that originates from the former CORGI engineer registration scheme, which was replaced by Gas Safe Register in 2009. The official document is called a Gas Safety Record, but CP12 is still universally understood in the industry and commonly appears on compliance checklists and insurance documents.
How often does a landlord need a gas safety certificate?
Every 12 months without exception. There is no grace period after expiry, an expired certificate, even by a single day, is a breach of the Gas Safety (Installation and Use) Regulations 1998. The check can be arranged up to two months before the current certificate expires, and the original renewal date is preserved.
Does a gas safety certificate cover radiators?
No. Gas safety checks cover gas appliances, pipework, flues, and ventilation. Radiators are water-based components that form part of the heating system rather than gas appliances in their own right. They are checked as part of boiler servicing or heating maintenance, not as part of the annual gas safety inspection. If a radiator fault affects boiler safety or gas pressure, the engineer will note it as part of the boiler assessment.
What if the tenant refuses to allow access for the gas safety check?
The landlord must make reasonable attempts to arrange access, document those attempts carefully, and pursue the matter actively. Forcing entry is not permitted without a court order. A detailed written record of all contact, requests, and responses provides evidence that the landlord has met their duty of care even if the check cannot be completed. Local authorities can assist in compelling access in some circumstances. Legal advice should be sought if a tenant persistently refuses.
What are the consequences of not having a valid gas safety certificate?
The consequences range from a criminal fine of up to £6,000 per appliance and local authority civil penalties of up to £30,000, to insurance invalidation, reputational damage, and in cases of gas-related incidents, prosecution under the Health and Safety at Work etc. Act 1974. Landlords without a continuous chain of valid records may also face difficulties in possession proceedings under the Renters' Rights Act 2025.
