What a CP12 Certificate Actually Is
CP12 stands for CORGI Proforma 12. CORGI was the body that registered gas engineers in the UK before Gas Safe Register took over on 1 April 2009. The proforma number stuck as industry shorthand, and you will still hear customers and letting agents ask for a CP12 even though the issuing body no longer exists. The correct modern name is Landlord Gas Safety Record, but both terms refer to the same legal document.
The certificate is a written record confirming that a Gas Safe registered engineer has inspected every gas appliance and flue in a rented property and found them safe for continued use. It is not a servicing record, though a service is often carried out at the same visit. The inspection and the service are two different activities, and only the inspection result is captured on the CP12.
The document must record specific information for each appliance: the appliance location, make, model, and type; the operating pressure and heat input where applicable; the inspector's findings on safety devices; the condition of the flue; and the overall result, which is either satisfactory, immediately dangerous, or at risk. If an appliance is condemned, that finding must appear on the certificate before any copy is handed to the tenant or landlord.
The Law Behind the CP12: Regulation 36 Explained
The legal basis for the CP12 is Regulation 36 of the Gas Safety (Installation and Use) Regulations 1998, made under the Health and Safety at Work etc. Act 1974. Regulation 36(1) places a duty on landlords who let residential property to ensure that every gas appliance and flue that they own, or that they are responsible for under the tenancy, is checked for safety at least once in every twelve-month period.
Regulation 36(3) requires the landlord to keep a record of each safety check for at least two years. Regulation 36(6) requires the landlord to give a copy of that record to each existing tenant within 28 days of the check, and to any new tenant before they move in. The engineer's obligation runs alongside this: under Regulation 36(2), only a Gas Safe registered engineer may carry out the check, and the certificate they produce is the evidence of compliance.
The Health and Safety at Work etc. Act 1974 sits above the 1998 Regulations as the enabling legislation. Section 33 of the 1974 Act sets out the criminal penalties for breaching duties imposed under it, which is where the serious custodial sentences come from. The 1998 Regulations inherit that enforcement framework, meaning a breach of Regulation 36 is a criminal offence, not a civil one.
- •Regulation 36(1): annual safety check required for every relevant gas appliance and flue
- •Regulation 36(2): only a Gas Safe registered engineer may carry out the check
- •Regulation 36(3): landlord must retain the record for at least two years
- •Regulation 36(6): copy to existing tenants within 28 days; to new tenants before move-in
- •Health and Safety at Work etc. Act 1974 s.33: criminal penalties for breach, including unlimited fines and up to two years imprisonment
Who Can Issue a CP12 Certificate
Only an engineer who holds a current Gas Safe Register licence and whose licence card covers the appliance type being inspected can lawfully carry out the safety check and issue the record. This is not a matter of competence in the general sense. The Gas Safe Register categorises competencies by appliance type, for example domestic natural gas, LPG, commercial catering, or unvented hot water. An engineer whose card does not cover the appliance category in question has no legal authority to sign off that appliance, even if they have been working on gas for thirty years.
As a sole trader, your Gas Safe licence is in your own name. Before attending a property, it is worth confirming that every appliance at the address falls within your card's listed competencies. Boilers, gas fires, hobs, and flued water heaters are all separate categories on some cards. If you inspect an appliance outside your registration and something later goes wrong, the certificate will be invalid and you will be personally liable.
There is no route for an unregistered person to issue a CP12, and there is no exemption for emergencies or temporary cover. If you are off sick and a landlord's annual check is due, the landlord must arrange for a different Gas Safe registered engineer to attend. Issuing a CP12 when you are not registered, or when your registration does not cover that appliance, is a criminal offence under Regulation 3 of the 1998 Regulations.
When a CP12 Certificate Is Required
The duty under Regulation 36 applies to landlords of residential property, not to owner-occupiers. The annual check must happen within every twelve-month period, meaning the anniversary date matters. If a landlord misses the deadline by even one day, the property is technically non-compliant for that entire period until a new check is carried out.
The requirement covers all gas appliances and flues that are provided under the tenancy agreement. That typically means the boiler, any gas fires, hobs, ovens, and any gas-fired water heaters. It does not cover appliances brought in by the tenant themselves, such as a portable gas heater the tenant owns. However, fixed appliances installed by a previous tenant that the current landlord has accepted responsibility for are included.
Houses in Multiple Occupation have the same requirement, but the logistics are more complex because multiple appliances may serve different tenants. Commercial landlords letting premises with a residential element, for example a flat above a shop, must also comply with Regulation 36 for the residential part. Serviced accommodation and holiday lets that operate as a business are subject to a parallel duty under Regulation 35 rather than Regulation 36, but the practical inspection requirement is effectively the same.
- •Applies to all residential lets including HMOs and mixed-use properties with a residential element
- •Annual check required: every 12 months, not every calendar year
- •Covers appliances the landlord owns or is responsible for under the tenancy
- •Does not cover tenant-owned portable appliances
- •Holiday lets and serviced accommodation fall under Regulation 35 but the inspection standard is the same
What the Inspection Must Cover
The Gas Safe Register publishes guidance on what the safety check must include, drawing on the requirements implicit in Regulation 36(1). At a minimum, the engineer must check that each appliance can be operated safely, that the flue system is performing correctly and not leaking products of combustion into the habitable space, that the gas supply pressure is adequate, and that there is adequate ventilation for combustion.
For each appliance, the engineer must test the operation of all safety controls, including flame failure devices, thermostats, and overheat cut-outs. Gas tightness of the pipework is normally checked as part of the visit, though it is worth being clear with the customer that gas tightness is a separate activity from the safety check itself. You are looking for evidence of spillage and testing the flue draw on open-flued appliances, as well as checking for signs of incomplete combustion such as sooting or yellow or orange flames where none should exist.
If you find an immediately dangerous situation, the appliance must be taken out of service before you leave the property. You must label it and obtain the tenant's or landlord's agreement in writing where possible. The CP12 must record the finding, and an immediately dangerous appliance cannot simply be noted and left. Failure to act on an immediately dangerous finding, and then issuing a satisfactory certificate, is potentially both a criminal and a regulatory offence.
- •Operating pressure and heat input checked for each appliance
- •Flue flow and integrity tested, including spillage test on open-flued appliances
- •Safety devices tested: flame failure, thermostat, overheat protection
- •Ventilation adequacy assessed
- •Gas tightness checked (separate activity but normally done at the same visit)
- •Any immediately dangerous or at-risk appliances must be recorded and acted upon
How Long a CP12 Certificate Lasts
A CP12 is valid for twelve months from the date of inspection. After twelve months, the landlord must arrange a new safety check, and a new certificate must be issued. There is no renewal or extension process. The previous certificate does not carry forward in any way.
The twelve-month clock runs from the date recorded on the certificate, not from the date it is handed to the tenant or posted to the landlord. This matters in practice because there is sometimes a gap of several days between the visit and the paperwork reaching the relevant parties. The inspection date is the legally significant date.
There is one useful practical rule: if the new safety check is carried out within two months before the existing certificate expires, the new certificate is backdated to the expiry date of the old one rather than the actual date of the new visit. This means landlords can avoid the anniversary creeping later each year. As the engineer, it is worth making the landlord aware of this rule, because it helps them maintain compliance without paying for an additional visit to realign the anniversary date.
Penalties for Getting It Wrong: The Real Figures
For landlords, failing to comply with Regulation 36 is a criminal offence under the Health and Safety at Work etc. Act 1974. The penalties on conviction in a magistrates' court are an unlimited fine and, for the most serious cases, up to six months' imprisonment. On conviction in a Crown Court, the maximum custodial sentence rises to two years. In practice, the Health and Safety Executive brings prosecutions where a landlord has persistently failed to comply, particularly where a tenant has been harmed.
In 2023 and 2024, HSE published several enforcement cases where landlords received fines ranging from £3,000 to over £25,000 for failures to carry out annual gas safety checks, with costs added on top. One case resulted in a suspended sentence. The HSE does not treat missed CP12s as a minor administrative oversight, particularly where the gas supply has been found to be unsafe at the time of eventual inspection.
For engineers, the consequences of issuing a defective or fraudulent CP12 are potentially more severe. Gas Safe Register can remove your registration immediately, ending your ability to work legally on gas. HSE can prosecute under Regulation 3 of the 1998 Regulations, which prohibits any person from carrying out gas work unless they are competent to do so. Issuing a certificate for an inspection you did not carry out, or certifying a safe result when the appliance was unsafe, could also constitute fraud under the Fraud Act 2006, carrying a maximum of ten years' imprisonment. Beyond the legal consequences, your public liability insurer would almost certainly void your policy for a fraudulent certificate.
- •Landlord: unlimited fine and up to two years imprisonment (Crown Court) for breach of Regulation 36
- •Landlord: six months' imprisonment maximum at magistrates' court
- •Real cases: fines of £3,000 to £25,000 plus prosecution costs in recent HSE actions
- •Engineer: Gas Safe registration removal for issuing defective certificates
- •Engineer: criminal prosecution under Regulation 3 of the Gas Safety (Installation and Use) Regulations 1998
- •Engineer: potential fraud prosecution under Fraud Act 2006 for knowingly false certification
A Worked Example: What Can Go Wrong
Consider a sole-trader gas engineer, call him Dave, who carries out a CP12 inspection at a two-bedroom flat in Birmingham on 14 March 2024. The boiler and a gas fire are both on site. Dave's Gas Safe card covers domestic natural gas boilers but he let his gas fire competency lapse when he renewed his registration the previous year. He carries out the full inspection, finds both appliances satisfactory, and issues the certificate dated 14 March 2024.
On 22 September 2024, the tenant calls the emergency gas line because the gas fire is producing a smell and the flame is burning yellow. The attending engineer condemns the fire, which has a cracked heat exchanger allowing partial combustion products into the room. The tenant has been experiencing headaches for weeks. HSE is notified. When they examine the CP12, they discover Dave's registration did not cover gas fires at the date of inspection.
Dave faces regulatory action from Gas Safe Register and a potential prosecution under Regulation 3 of the Gas Safety (Installation and Use) Regulations 1998 for carrying out gas work outside his competence. His public liability insurer, on seeing the registration evidence, declines to defend the civil claim from the tenant. The landlord also faces a Regulation 36 complaint because the certificate on file was not issued by an appropriately registered engineer, meaning no valid safety check was carried out at all for that appliance. The landlord's fine in the subsequent HSE prosecution is £11,500 plus £4,200 costs. Dave's registration is suspended pending investigation. The entire chain of events traces back to one lapsed competency category on a Gas Safe card.
Record-Keeping and Issuing Copies Correctly
Regulation 36(3) requires the landlord to keep a copy of each CP12 for a minimum of two years. As the engineer, you are not under a specific obligation to retain copies for that period, but it is strongly advisable to keep your own records for at least six years. If a dispute arises about what was inspected and what was found, your copy of the certificate is your defence. The Limitation Act 1980 allows contract claims to be brought up to six years after the event, and HSE investigations can look back well beyond the two-year landlord retention period.
Regulation 36(6) requires the landlord, not the engineer, to provide copies to tenants. However, in practice many engineers hand a copy directly to the tenant on the day of the visit when the tenant is present. There is nothing wrong with doing this, and it is good practice. If the tenant is not present and you are handing the certificate to the landlord's managing agent, make clear in writing that the agent must pass a copy to each tenant within 28 days.
The certificate must be legible and contain all the required fields. A handwritten certificate on a standard proforma is perfectly legal provided it is complete and accurate. The format is not prescribed by Regulation 36, only the content. That said, a printed or digitally generated certificate is easier to read, harder to dispute, and faster to produce at the property.
- •Landlord retains CP12 for minimum two years (Regulation 36(3))
- •Engineer should retain own copy for at least six years as a best-practice defence measure
- •Copy to existing tenants: within 28 days of inspection (Regulation 36(6))
- •Copy to new tenants: before they move in
- •Format not prescribed: handwritten or digital both valid provided all required fields are complete
A Note on Gas Tightness Testing: The October 2026 Change
If you carry out gas tightness testing as part of your CP12 visit, which most engineers do as a matter of course, be aware of a significant procedural change coming into effect on 1 October 2026. IGEM/UP/1B Edition 4 replaces the previous edition and changes how permissible pressure drop is determined during tightness testing. Under the previous edition, the acceptable pressure drop was determined by meter size. Under Edition 4, it is determined by the installation volume of the pipework.
The practical implication is that the pass or fail threshold for a tightness test will change for many installations from 1 October 2026 onward. Edition 4 also removes the previous rule that allowed a perceptible gauge movement to be attributed to the installation pipework. Any perceptible movement on the gauge after 1 October 2026 must be investigated rather than recorded as within tolerance.
This does not change the CP12 certificate format or the Regulation 36 requirements. The safety check duties remain as described in this guide. But if you carry out tightness testing during CP12 visits, make sure you are familiar with the Edition 4 methodology before October 2026 and that your test equipment and recording practices are updated accordingly.
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