What a CP12 Actually Is and Why It Exists
The CP12 is the common shorthand for the Landlord Gas Safety Record, sometimes also called the Gas Safety Certificate. It is not a certificate in any formal accreditation sense. It is a written record of the safety checks a Gas Safe registered engineer has carried out on every gas appliance and flue in a rented property. The name CP12 comes from the old Corgi form reference and has stuck in the trade even though Corgi no longer operates.
The legal duty to produce this record comes from Regulation 36 of the Gas Safety (Installation and Use) Regulations 1998. Regulation 36(3) requires the landlord to ensure a check is carried out within 12 months of each previous check, and at the start of any new tenancy. Regulation 36(6) requires a copy of the record to be given to the existing tenant within 28 days of the check, and to any new tenant before they move in. Regulation 36(7) requires the landlord to retain the two most recent records.
Your role as the gas engineer is to carry out the checks to the required standard and issue the completed record. If you issue a record that contains false information, you face prosecution under the Health and Safety at Work etc. Act 1974. The HSE can pursue both civil and criminal penalties, including unlimited fines in a Crown Court and up to two years imprisonment for the most serious breaches. That is not a theoretical risk — the HSE does prosecute gas engineers, and a number of cases each year involve incomplete or falsified CP12 records.
The Worked Example: A Realistic CP12 From Start to Finish
Below is a complete worked example based on a sole trader, Dave Marsh of DM Gas Services, Gas Safe Registration 567890, carrying out an annual landlord gas safety check at a two-bedroom mid-terrace rental property in Coventry. The landlord is Mr P. Anand, the tenant is Ms S. Okafor. The property has a Worcester Bosch Greenstar 25i combi boiler installed in the kitchen and a Baxi gas fire in the living room. Date of inspection: 14 July 2025.
LANDLORD GAS SAFETY RECORD. Engineer name: Dave Marsh. Company name: DM Gas Services. Gas Safe Register number: 567890. Engineer Gas Safe ID card number: 123456. Date of inspection: 14/07/2025. Property address: 22 Balmoral Road, Coventry, CV3 4RT. Landlord name and address: Mr P. Anand, 45 High Street, Coventry, CV1 2AB. Tenant name: Ms S. Okafor.
APPLIANCE 1. Appliance type: Combination boiler. Appliance location: Kitchen. Make and model: Worcester Bosch Greenstar 25i. Flue type: Room sealed. Appliance safe to use: Yes. Operating pressure (mbar): 20.0. Heat input (kW): 29.5. Safety devices operating correctly: Yes. Ventilation provision adequate: N/A (room sealed). Any immediately dangerous or at-risk situation: No. Defects identified: None. Remedial action required: None. APPLIANCE 2. Appliance type: Gas fire. Appliance location: Living room. Make and model: Baxi Bermuda 502. Flue type: Open flued. Appliance safe to use: Yes. Operating pressure (mbar): 19.8. Heat input (kW): 4.2. Safety devices operating correctly: Yes. Ventilation provision adequate: Yes. Any immediately dangerous or at-risk situation: No. Defects identified: Slight debris accumulation in firebox. Remedial action: Advised tenant and landlord to have firebox cleaned before winter use. LANDLORD SIGNATURE: P. Anand. ENGINEER SIGNATURE: D. Marsh. DATE: 14/07/2025.
Notice that every field is populated. The engineer has recorded the specific operating pressure in millibar for each appliance rather than simply writing 'normal'. The flue type has been noted per appliance because an open-flued appliance has different ventilation and spillage test requirements to a room-sealed one. The minor defect on the gas fire has been recorded, an advisory issued, but the appliance has not been condemned because it is not immediately dangerous. That distinction matters legally, as we cover below.
Breaking Down Each Section of the Record
The engineer identification section must include your full name, your trading name or company name, and critically your Gas Safe Register number. Your Gas Safe ID card number is separate from your registration number — one identifies the business, the other identifies you as an individual engineer. Both must be present. An employer or sole trader operating without Gas Safe registration commits an offence under Regulation 3 of the Gas Safety (Installation and Use) Regulations 1998, and any CP12 issued by an unregistered engineer is worthless in law.
The property and landlord details section seems straightforward but generates a surprising number of disputes. The landlord address should be the landlord's actual correspondence address, not the rental property address. If there is a managing agent involved, it is best practice to record both the landlord's name and the agent's name, so there is no ambiguity about who received the record and on what date. Record the date you actually hand the copy to the tenant or post it — Regulation 36(6) gives a 28-day window from the inspection date, not from when you happen to get round to it.
The appliance section is where most errors occur. You must record a separate entry for every gas appliance in the property, including any that are not in use but are still connected to the gas supply. An appliance that has been disconnected and capped off does not need a safety entry, but you should note its existence and the capping arrangement. Operating pressure must be recorded as a specific figure in millibar, not as a tick in a box. Heat input in kilowatts should be taken from the data plate or commissioning documentation.
- •Engineer name, Gas Safe registration number, and individual ID card number are all mandatory fields.
- •Record operating pressure in mbar as a specific number for each appliance.
- •Flue type (room-sealed, open-flued, flueless) dictates which checks apply.
- •Ventilation adequacy must be assessed and recorded, even if the result is N/A for room-sealed appliances.
- •All safety devices must be individually tested and the results recorded.
- •Any defect must be categorised: Immediately Dangerous (ID), At Risk (AR), or advisory only.
- •Both landlord and engineer signatures with the date complete the record.
The ID/AR/Advisory Categorisation and What Each Means
The Gas Industry Unsafe Situations Procedure (GIUSP) defines three categories for defects: Immediately Dangerous (ID), At Risk (AR), and Not to Current Standards (NCS), which is sometimes recorded as an advisory. These categories determine what action you must take and what you record on the CP12. If an appliance is ID, you must disconnect it or make it safe before you leave, with the landlord's or tenant's agreement. If agreement is refused and the situation is genuinely dangerous, you can disconnect without consent under Regulation 39 of the Gas Safety (Installation and Use) Regulations 1998.
An At Risk situation is one where the appliance is not immediately dangerous but could become so. In this case, you issue a warning notice, advise the landlord in writing not to use the appliance, and record the situation on the CP12. You mark the appliance as 'Unsafe to Use' on the record. The landlord then has a duty under Regulation 36(2) to ensure the appliance is not used until repaired and re-checked.
The advisory category, which corresponds to NCS in the GIUSP, covers situations where an appliance does not meet current standards but presents no immediate or at-risk safety concern. The gas fire in our worked example falls here. You record the defect, note the advice given, but mark the appliance as safe to use. Always word the advisory carefully and in writing, because if that appliance later causes an incident and your advisory was vague, you may face questions about whether you discharged your duty of care under the Health and Safety at Work etc. Act 1974 section 3, which places duties on self-employed persons in relation to persons other than their employees.
Open-Flued Appliances: The Spillage Test and Why It Must Be Recorded
Open-flued appliances, such as the Baxi gas fire in our example, require an additional set of checks that room-sealed appliances do not. The most important is the spillage test, which checks whether combustion products are being drawn up the flue correctly or are spilling back into the room. This is typically carried out using a smoke match or electronic detector at the draught diverter. The result must be recorded on the CP12 as a pass or fail, not simply left blank.
Ventilation adequacy is also critical for open-flued appliances. The room must have sufficient permanent ventilation to support combustion. If a room has been sealed up since the appliance was originally installed, perhaps by a tenant fitting draught excluders or blocking air bricks, the ventilation may no longer be adequate. This should be assessed against the original installation requirements and any changes noted. Inadequate ventilation on an open-flued appliance is typically an At Risk situation at minimum.
Carbon monoxide alarms are not a check box on the CP12 itself, but under the Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022 (which amended the 2015 Regulations), landlords in England are required to fit a CO alarm in every room with a fixed combustion appliance, including gas fires and boilers, from 1 October 2022. You should note on the record whether a CO alarm is present and functioning. While its absence is the landlord's legal problem rather than yours, recording it protects you if a future incident leads to questions about what you observed.
Issuing the Record: Timing, Format, and Retention
Regulation 36(6) of the Gas Safety (Installation and Use) Regulations 1998 requires the landlord to provide the tenant with a copy of the safety record within 28 days of the inspection. As the gas engineer, you are not personally required by law to hand it to the tenant directly, but in practice most sole traders hand a copy to whoever is present at the property on the day and send another copy to the landlord. That is sound practice. Keep a copy for yourself too — there is no statutory requirement for the engineer to retain a copy, but given that claims under the Limitation Act 1980 can be brought up to six years after a breach of contract or negligence event, holding your records for at least six years is sensible.
The format of the record is not prescribed in exact detail by law. It does not have to be on a specific printed form. It can be produced digitally and signed electronically, provided the content meets the requirements set out in Regulation 36. That said, Gas Safe Register provides a standard form that covers all required fields, and most sole traders use either the Gas Safe form, a version from their scheme provider, or a job management software template. Whatever format you use, every mandatory field must be present.
Where properties have multiple appliances or multiple units under one landlord, each property requires its own separate CP12. You cannot issue a single record covering a landlord's entire portfolio. If you service a block of six flats for the same landlord on the same day, that is six separate records. Each tenant in Regulation 36 terms is a separate party with a separate right to receive their own record within 28 days.
What Happens When Things Go Wrong: Penalties and Prosecutions
The HSE enforces the Gas Safety (Installation and Use) Regulations 1998 and takes prosecutions seriously. A landlord who fails to have the annual check carried out at all, or fails to provide the record to the tenant within 28 days, faces a fine of up to £6,000 in a magistrates' court or an unlimited fine in a Crown Court, as well as up to two years imprisonment for the most serious offences. The Health and Safety at Work etc. Act 1974 section 33 sets out the full range of offences and penalties.
As the gas engineer, your exposure is different but equally real. If you issue a CP12 for checks you did not properly carry out, or record readings you did not take, that is a falsification of a safety record. The HSE has prosecuted engineers for exactly this. Beyond criminal liability, your Gas Safe registration can be revoked, which effectively ends your ability to work legally in the gas industry. Your professional indemnity insurer may also decline to cover you if the claim arises from a falsified or negligently completed record.
Civil liability runs alongside criminal exposure. If a tenant suffers a gas-related injury or death and it emerges that the CP12 contained incorrect information or that required checks were skipped, the engineer can face a civil negligence claim. Under the Consumer Rights Act 2015 section 49, work carried out for consumers must be done with reasonable care and skill. Even where the client is technically the landlord rather than the tenant, the engineer owes a duty of care to the occupants of the property. That duty is not discharged by simply filling in a form.
Common Mistakes Sole-Trader Gas Engineers Make on CP12s
The single most common error is incomplete fields. Engineers in a hurry leave the operating pressure as a tick rather than a figure, or leave the ventilation box blank for a room-sealed appliance rather than writing N/A with a brief note. Blank fields look like uncompleted checks to an HSE inspector, even if you did carry out the check. The rule is straightforward: if there is a field, it gets an entry.
The second most common mistake is failing to record advisory defects. Some engineers only record defects that require immediate action. If a heat exchanger is showing early signs of corrosion, that is worth noting as an advisory even if it is not yet at the At Risk threshold. Failing to note it means the landlord has no written record that you flagged the issue, and if it deteriorates before the next annual check, questions will be asked about what you observed the previous year.
A third recurring problem involves properties with multiple appliances where one appliance is listed but others are missed. This often happens with gas cookers, tumble dryers with gas connections, or gas-powered booster heaters in bathrooms. Every connected appliance must be on the record. If you arrive at a property and discover an appliance that was not on the previous engineer's record, note it, check it, and include it. Do not simply replicate what the last CP12 contained without verifying it against what is actually in the property.
- •Never leave operating pressure as a tick. Record the actual millibar figure.
- •Mark ventilation as N/A for room-sealed appliances rather than leaving the field blank.
- •Record every gas appliance in the property, including cookers and gas tumble dryers.
- •Document all advisory defects, not just ID and AR situations.
- •Confirm the date of issue and the method of delivery to the tenant.
- •Keep your own copy for at least six years to cover the Limitation Act 1980 window.
- •Do not reproduce the previous CP12 without independently verifying each appliance.
Pricing Your CP12 Work as a Sole Trader
Sole traders doing landlord gas safety work typically charge between £60 and £120 for a single appliance check, depending on location and whether a boiler service is included at the same visit. If you are carrying out a full boiler service alongside the CP12 check, it is common to price the service and the safety record as a combined job, typically between £90 and £150, with additional appliances charged separately at £20 to £40 each. These are rough market rates as of 2025 and vary by region.
Under the Consumer Rights Act 2015 section 51, where no price has been agreed in advance, the consumer is required to pay a reasonable price. That standard applies even on straightforward repeat jobs where a verbal agreement is the norm. Having your pricing in writing, even a simple text message or email confirmation before the visit, protects you if a landlord later disputes the charge. It also removes any argument that the charge was unreasonable.
If a landlord is slow to pay after you have issued the CP12, the Late Payment of Commercial Debts (Interest) Act 1998 entitles you to charge statutory interest at 8% above the Bank of England base rate on overdue commercial invoices, plus a fixed compensation amount of £40 for debts under £1,000, £70 for debts between £1,000 and £9,999, and £100 for debts of £10,000 or more. Note that this Act applies to business-to-business transactions, so it covers invoices to landlords acting in a commercial capacity, not private individuals paying for their own home.
Variations: New Tenancies, HMOs, and Commercial Properties
For a new tenancy, Regulation 36(6)(b) of the Gas Safety (Installation and Use) Regulations 1998 requires the landlord to provide the CP12 to the new tenant before they move in, not within 28 days. If you are doing a pre-tenancy check, note this on the record and advise the landlord explicitly in writing that the record must be handed to the incoming tenant before the tenancy starts. That written advice covers you if the landlord fails to comply.
Houses in Multiple Occupation (HMOs) add complexity because there may be gas appliances in individual rooms as well as communal areas. Each appliance requires its own entry on the record. Some local authorities require HMO landlords to provide evidence of the current CP12 as part of their licensing conditions. The record format and legal requirements are the same as for standard lets, but the number of appliances and the number of tenants who need to receive a copy multiply accordingly.
Commercial properties and mixed-use premises fall outside the residential landlord provisions of Regulation 36, but the gas engineer's duty to carry out safe work and issue appropriate documentation does not disappear. For commercial clients, you would typically issue a Gas Appliance Service Report or a similar document rather than a CP12. The Health and Safety at Work etc. Act 1974 still applies to all work you carry out, and the standard of care required under the Consumer Rights Act 2015 section 49 applies where the client is a business rather than an individual consumer, though the enforcement mechanism differs slightly.
Generating Your CP12 Records Without the Paperwork Headache
Filling in a CP12 by hand on a printed form works, but it is slow, prone to illegibility, and means your records are sitting in a folder in your van rather than somewhere you can retrieve them quickly. TradeDoc AI at tradedoc.co.uk lets sole-trader gas engineers generate a fully populated, professional landlord gas safety record in around two minutes by answering a short set of prompts covering the engineer details, property address, appliance information, and check results.
The output covers all the fields required under Regulation 36 of the Gas Safety (Installation and Use) Regulations 1998, is formatted for easy reading by landlords and tenants, and can be saved, emailed, or printed immediately from your phone or laptop. It also stores your previous records so you are not hunting through paperwork when a landlord rings asking for a copy of last year's check.
It is not a substitute for carrying out the checks properly and knowing your trade. But if your job management paperwork is currently a pile of carbon copy forms, it is worth ten minutes of your time to look at what a digital alternative actually does.
