What Does a CP12 Certificate Include?

A landlord usually asks about the paperwork after the engineer has finished, but the more useful question is earlier in the process: what does CP12 certificate include, and does it actually show that the property has been checked properly? If you are responsible for a rented property, it helps to know exactly what should appear on the certificate, what the inspection covers, and where the limits are.

A CP12 certificate is the record produced after a Gas Safe registered engineer carries out a landlord gas safety check. In practice, people often use “CP12” as shorthand for the Gas Safety Record. It confirms that the relevant gas appliances, pipework and flues that were inspected on that visit have been checked for basic safety and recorded correctly.

That matters because the certificate is not just a box-ticking document. For landlords and property managers, it is part of meeting a legal duty. For tenants, it provides evidence that gas appliances in the property have been inspected by a qualified engineer. For managing agents and businesses, it offers a clear written record that can be filed, issued and referred back to if questions come up later.

What does a CP12 certificate include in practice?

The certificate includes key details about the property, the engineer, the appliances checked and the outcome of the inspection. At a minimum, you should expect to see the address of the property, the date of the check, the name and Gas Safe registration details of the engineer, and the name and address of the landlord or agent where applicable.

It will also identify each gas appliance or flue that has been inspected. That might include a boiler, gas hob, gas fire or warm air unit, depending on what is installed at the property and what falls within the landlord’s responsibility. Each item should be described clearly enough for it to be identified later, especially where there is more than one appliance on site.

Alongside that, the record should show the safety outcome of the inspection. That normally includes whether the appliance was found to be safe to use at the time of testing, whether the burner pressure or gas rate was satisfactory where relevant, whether the flue was operating correctly, and whether adequate ventilation was present. If defects are found, those should be recorded too.

The main sections you will usually see on a CP12

Although layouts vary slightly between engineers or software systems, most certificates cover the same core information. The first section is usually the property and responsible person details. This keeps the record tied to the right address and landlord, which sounds obvious, but accuracy matters if you manage several properties.

The next section normally lists the appliances checked. Each appliance may have its location noted, such as kitchen, utility room or lounge, along with its make, model or appliance type. This helps avoid confusion where replacements have been carried out since the last inspection.

Then comes the actual inspection record. This is where the engineer notes whether the appliance appears safe, whether the flue is satisfactory, whether ventilation is adequate, and whether the safety devices are working properly. In some cases, combustion readings may also be recorded, especially on modern boilers where analyser testing forms part of good practice.

A final section usually covers faults, remedial action and engineer declaration. If an appliance is classed as unsafe, that should be stated clearly. If the engineer has carried out remedial work on the same visit, it may be recorded there. If further repairs are needed, the certificate should make that clear rather than leaving the landlord to guess.

What checks are carried out during the inspection?

A CP12 certificate records the outcome, but it helps to understand what the engineer is actually checking. The inspection is focused on gas safety, not on giving the whole heating system a full service unless that has been booked separately.

The engineer will check appliances for obvious signs of unsafe operation. That can include poor flame picture, signs of incomplete combustion, damage, incorrect installation positioning, or signs that fumes may not be clearing properly. Flues are checked to confirm they are fitted correctly, are not blocked, and are discharging safely.

Ventilation is another key part of the process. If an appliance relies on permanent ventilation, that provision needs to be present and unobstructed. The gas tightness of the installation may also be tested to check for leaks on the system.

Where relevant, the engineer may check burner pressure or gas rate against the manufacturer’s requirements. Safety devices should also be considered. If a boiler or other appliance has controls designed to shut it down under unsafe conditions, those need to be in proper working order.

What a CP12 certificate does not include

This is where many landlords get caught out. A CP12 is not the same as a boiler service. The two are often booked together, which makes sense, but they are not identical.

A gas safety check is there to confirm whether the appliances inspected are safe at the time of the visit. A boiler service is more focused on maintenance, efficiency, component condition and helping to prevent breakdowns. A boiler may technically pass a gas safety check but still be overdue for servicing, running inefficiently, or showing wear that should be addressed before it becomes a more expensive problem.

A CP12 also does not usually cover tenant-owned appliances. If a tenant has supplied their own gas cooker, for example, the landlord’s legal responsibility can be different from appliances provided as part of the tenancy. Even so, it is always worth being clear about who owns what before the visit, so nothing is assumed and nothing important is missed.

The certificate is not a blanket guarantee that every part of the heating system is fault-free for the next 12 months either. It records the condition and safety status at the time of inspection. Things can still fail later, particularly with older boilers or heavily used appliances.

If faults are found, what should appear on the certificate?

If an appliance is unsafe, the certificate should make that very clear. The engineer may classify the issue depending on the type and severity of risk. In practical terms, the important point for the landlord is whether the appliance can remain in use, whether it has been turned off, and what action is required next.

Some issues can be dealt with there and then if parts, time and access allow. Others will need a return visit. The record should not be vague. It should state what was found and whether further remedial work is needed.

If an appliance has been disconnected for safety reasons, the landlord should treat that as urgent. Leaving the paperwork in a file without arranging the repair creates risk for the tenant and potential legal difficulty for the landlord.

Who needs the certificate and when?

Landlords must keep a record of the gas safety check and provide a copy to existing tenants within the required timeframe. New tenants must also receive the current record before moving in. For managing agents, speed matters here. Delayed paperwork creates avoidable chasing and, in some cases, compliance problems.

For that reason, many landlords prefer to use an engineer who can issue the certificate promptly on the same day. That is particularly useful when properties are changing tenants, when portfolios are being managed at scale, or when an inspection has been left close to the deadline.

Homeowners do not usually need a CP12 unless they are renting out the property, but some still ask what the certificate includes because they are preparing to let a home for the first time. In that situation, it is worth booking early rather than waiting until keys are about to be handed over.

What does a CP12 certificate include for different property types?

The basics stay the same, but the detail can vary depending on the building. In a small flat with one combi boiler and a hob, the certificate may be quite straightforward. In a larger house with multiple gas appliances, the record will naturally be longer because each relevant appliance and flue needs to be identified and checked.

For small commercial premises, there can be additional practical considerations around access, trading hours and the type of appliances installed. The inspection still needs to be recorded properly, but the setup may be less standard than in a domestic rental property.

That is why it helps to use a contractor who is used to working across different property types and can explain clearly what is covered before the visit starts. If you are not sure whether a specific appliance falls within the check, ask before the appointment rather than after the paperwork has been issued.

For landlords, agents and businesses, the safest approach is simple: treat the CP12 as an essential compliance record, not a last-minute admin task. When the certificate is clear, complete and issued promptly by a Gas Safe registered engineer, it gives you something more useful than paperwork - it gives you confidence that the right checks have actually been done.