Gas Safety Certificate for Landlords (CP12)

A gas safety certificate, usually called a CP12, is the record a Gas Safe registered engineer produces after checking every gas appliance, flue and pipe you are responsible for in a rented property. If your rental has a gas boiler, gas fire, gas hob or gas water heater, you need a valid certificate in place before a tenant moves in, and a new one at least once every 12 months after that.

The certificate itself is not the safety check, it is the evidence that the check happened. It records which appliances were tested, what the engineer found, and whether anything needs repairing before the property is safe to let. Landlords who skip the check, let it lapse, or fail to give tenants a copy are breaking the law, and an out-of-date certificate can also affect a landlord insurance claim if something goes wrong.

Legal requirement

The duty comes from the Gas Safety (Installation and Use) Regulations 1998. As a landlord, you must:

• Have every gas appliance and flue you own checked by a Gas Safe registered engineer at least once every 12 months.
• Keep a record of each check for at least two years.
• Give a copy of the current certificate to existing tenants within 28 days of the check.
• Give a copy to new tenants before they move in, or to sitting tenants as soon as the first check under a new tenancy is done.

This applies to any rented property in England, Wales, Scotland or Northern Ireland where the landlord supplies gas appliances, whether that is a whole house, a flat, or a single room in a shared house. If a tenant brings their own gas appliance, such as a cooker they own outright, that appliance is not the landlord's responsibility. Your own pipework and any appliances you supplied still are, regardless of who uses them.

Only an engineer on the Gas Safe Register can legally carry out gas work or issue a certificate in Great Britain. Checking the engineer's Gas Safe ID card, and confirming they are registered for the specific appliance type you need checked (boiler, cooker or LPG, for example), takes a couple of minutes on the Gas Safe Register website. It is worth doing every time you use a new contractor, and periodically thereafter, since registration can lapse.

What is checked

During the annual check, the engineer inspects each gas appliance, along with its flue and connecting pipework, for:

• Tightness testing, to confirm there are no gas leaks anywhere in the system.
• The physical condition and stability of each appliance and its fittings.
• Correct operating pressure and, where relevant, heat input against the manufacturer's specification.
• Safety devices, such as flame failure devices, to check they shut off the gas supply correctly.
• Ventilation, to confirm air can reach the appliance safely.
• Flue performance, to confirm that products of combustion, including carbon monoxide, are safely removed from the property.

Where the engineer finds a fault, they classify it by severity. In the most serious cases, they may need to disconnect or "cap off" an appliance on the spot for safety. A property should never continue to be let with a gas appliance that has failed a safety check and not since been repaired, replaced or safely disconnected, even if that means a short delay to a tenancy start date.

Cost ranges

Costs vary by region, property type and how many appliances need checking, so treat any figure you see as a guide rather than a quote. A single gas safety check on a property with one boiler is typically a modest fixed fee, and many landlords combine it with an annual boiler service booked from the same engineer visit, which costs more than the check alone but avoids a second call-out charge later in the year. Properties with several appliances, such as a boiler, a gas fire and a gas hob, cost more to check than a single-appliance flat, since each appliance adds time to the visit.

If you manage more than one or two properties, it is often more cost-effective to agree an annual arrangement with one Gas Safe engineer or letting agent rather than booking each check separately as it comes up. This also makes it easier to plan staggered renewal dates across a portfolio so you are not managing several access visits in the same week. For an up-to-date sense of local pricing, get quotes from two or three Gas Safe registered engineers covering the property's area rather than relying on a single national average figure, since prices can differ noticeably between regions. Our guide to gas safety certificate costs looks at this in more detail, including what tends to push the price up.

Record keeping

You must keep the current gas safety record, and your two most recent previous records, for at least two years. In practice, most landlords keep every historical certificate for as long as they own the property, since it builds a useful maintenance history. That history matters if an appliance is later replaced under warranty, if you sell the property and need to show buyers or their solicitors that gas safety has been maintained, or if a dispute ever arises over when a fault was first identified.

Store a digital copy alongside any paper one. If you use letting software or a compliance register, upload the certificate as soon as the engineer issues it, note the expiry date immediately, and record which appliances were checked and any remedial work carried out. This matters most once you have several properties on different renewal cycles, because a missed certificate on even a single property is still a breach of the regulations, regardless of how well the rest of your portfolio is managed.

Reminders

Gas safety certificates lapse exactly 12 months after the date of the previous check, not the date you happen to remember to book the next one. Gas Safe engineers can carry out a renewal check up to two months before the current certificate expires without losing any cover, because the new certificate's 12-month validity runs from the old expiry date rather than from the new check date. This gives you a genuine two-month window to arrange tenant access and avoid a last-minute scramble as the deadline approaches.

The most common way landlords fall out of compliance is not a deliberate decision to skip a check, but simply losing track of the date, particularly across a portfolio with certificates expiring at different times of year. A spreadsheet can work for one or two properties. Once you have several properties, or several types of certificate to track alongside gas safety, such as an EICR or an EPC, a dedicated compliance calendar with automatic reminders is far more reliable than relying on memory or a diary note.

How Property HQ helps

Property HQ keeps every gas safety certificate, alongside EICR, EPC and licensing dates, in one compliance register with automatic reminders before each one expires. Instead of checking a spreadsheet or a folder of PDFs property by property, you get a single view of every certificate's status across your whole portfolio, with enough notice to book the next engineer visit before anything lapses. See our landlord certificates checklist for the full list of documents most portfolios need to track. For the wider set of legal duties that sit alongside gas safety, our landlord legal responsibilities guide is a useful next stop.

Disclaimer

This guide is general information for UK landlords, not legal or safety advice. Gas work must only ever be carried out by a Gas Safe registered engineer. Check GOV.UK and the Gas Safe Register for current rules and to verify an engineer before any visit.