Gas Safety Certificate (CP12) explained for UK landlords

CP12 is the old British Gas product code for the Landlord Gas Safety Record. The official name is now CP12 or simply Gas Safety Record, and the legal source is the Gas Safety (Installation and Use) Regulations 1998, Regulation 36.

The certificate confirms that every gas appliance, flue and pipework owned by the landlord has been inspected for tightness, ventilation, combustion performance and safety device operation by a Gas Safe registered engineer.

Any property where the landlord supplies gas equipment, including a gas boiler, gas cooker, gas fire, gas hob, gas oven, or any flue, must have a valid CP12 before a new tenancy begins and renewed at least every twelve months thereafter.

A copy must be supplied to the existing tenant within 28 days of inspection, and to a new tenant before they move in. Records must be retained for at least two years.

If the only gas item in the property belongs to the tenant (such as their own gas cooker brought from a previous home), the CP12 still applies to landlord-owned pipework and flues, even if no appliances are present.

Most landlords pay between £60 and £120 for a CP12, depending on the number of appliances and the region. A single boiler in a one-bedroom flat sits at the bottom end; a property with a boiler, hob, oven and gas fire pushes towards the top.

Combining a CP12 with an annual boiler service often comes in cheaper than booking them separately. Many Gas Safe engineers offer a bundled package for £90 to £150.

Failing to hold a current CP12 is a criminal offence under the Health and Safety at Work etc Act 1974. Penalties range from unlimited fines to, in cases of fatal carbon monoxide poisoning, custodial sentences for landlords. Insurance can be voided where there is no valid certificate.

If you also fail to serve the certificate on the tenant, you cannot serve a valid Section 21 eviction notice in England.

Only Gas Safe registered engineers can issue a CP12. Always ask for the engineer's Gas Safe ID card before they start work and verify the registration at gassaferegister.co.uk. The card includes a photo, registration number and a list of the gas categories the engineer is qualified to work on.

Booking through an established marketplace removes the verification step from your plate. We list the major UK options on the gas safety certificate page with current commission-disclosed links.