Gas Safety Certificate (CP12) explained: rules, cost and renewal

The annual gas safety check is one of a landlord's clearest legal obligations, and one of the few where non-compliance is a criminal offence rather than a civil matter. Here's everything you need to know about the CP12, what it covers, and how to stay on top of renewals.

What is a CP12 (gas safety record)?

A CP12 — officially a Landlord Gas Safety Record — is the document produced after a Gas Safe registered engineer checks all gas appliances and flues in a rental property. It records:

• Each gas appliance and flue checked
• The location of each appliance
• The date of the inspection
• Any defects found and actions taken
• The engineer's Gas Safe registration number
• Whether each appliance has been confirmed safe for use

The term "CP12" comes from the old Corgi Proforma 12 — Corgi was the predecessor to Gas Safe Register, which took over in 2009. You'll still hear CP12 used everywhere even though the official document name is now "Gas Safety Record".

The legal requirement

Under the Gas Safety (Installation and Use) Regulations 1998:

• Landlords must arrange an annual gas safety check for all gas appliances and flues that they provide in the property.
• The check must be carried out by a Gas Safe registered engineer.
• New tenants must receive a copy of the gas safety record before they move in.
• Existing tenants must receive a copy within 28 days of the annual check.
• Landlords must keep copies of gas safety records for a minimum of two years.

What gets checked

The engineer checks every gas appliance provided by the landlord — typically the boiler, gas cooker, gas fires, and all associated flues and pipework. They confirm each appliance is operating safely and note any defects found. Anything unsafe is flagged for immediate attention.

If an appliance is found to be immediately dangerous, the engineer is required to disconnect it (or advise strongly if disconnection isn't straightforward). It cannot be returned to use until repaired.

What it doesn't cover

The gas safety check is a safety inspection, not a maintenance service. It confirms the appliance is safe — it doesn't clean the heat exchanger, analyse combustion efficiency, or check safety devices in detail the way a boiler service does. Most landlords book the annual gas safety check and boiler service together on the same day to reduce call-out costs and keep the renewal dates aligned.

What it costs

A standard landlord gas safety check typically costs £60–£120 depending on the number of gas appliances, the property's location, and the engineer. Properties with multiple gas appliances (boiler, gas cooker, gas fire) will usually pay more than those with a boiler only. London and the South East tend to be more expensive.

Some landlord insurance policies and home emergency cover plans include an annual gas safety check — worth checking before booking separately.

The consequences of non-compliance

Failing to carry out the annual gas safety check or to provide tenants with the certificate is a criminal offence under the 1998 Regulations. The HSE can prosecute landlords, and consequences include unlimited fines and up to two years imprisonment.

Beyond criminal liability:

• Landlord insurance policies typically exclude claims related to unserviced gas appliances.
• Failure to provide the gas safety record to tenants can prevent a landlord from serving a valid Section 21 (no-fault eviction) notice.

Practical notes for landlords

Timing: Book the annual check a few weeks before the anniversary date to allow for rescheduling. Don't let it lapse even by a few days — the anniversary date is when the certificate runs out, not when you get round to renewing it.

Multiple properties: Track each property's gas safety check date separately. They won't all be on the same date, and missing one because you confused it with another is an easy mistake with real consequences.

Record-keeping: Keep a copy of every gas safety record for at least two years. In practice, keep them permanently — they're useful if a dispute arises about a tenant's claim that an appliance was faulty when they moved in.

Access: Include a right-of-access clause for gas safety checks in your tenancy agreement. Give tenants proper written notice before the visit.

How JustTaggit helps

Attach each property's gas safety record to the relevant boiler's QR code in JustTaggit. When the next check is due, you get a reminder — not the day after the certificate expires, but with enough time to book and confirm the engineer. The record is retrievable instantly for a tenant request, an agent's audit, or a Section 21 process. For the full compliance picture, see our landlord safety compliance guide.

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