What a Gas Safety Certificate Actually Is (and What It Is Not)
A gas safety certificate, formally called a Gas Safety Record, is the written evidence that a Gas Safe registered engineer has inspected gas appliances and associated pipework and found them to be safe for continued use. The document is often called a CP12, which is a Gas Safe shorthand reference to the inspection checklist, not a legal term. The certificate itself is the legally mandated record under Regulation 36 of the Gas Safety (Installation and Use) Regulations 1998.
It is important to be clear about what the certificate does not do. It does not certify that work has been carried out, and it should never be confused with a Building Regulations Gas Installation Completion Certificate or a commissioning record for a new boiler. Those are separate documents. A CP12 is specifically an inspection record confirming the current safety status of existing gas appliances in a property.
The certificate also does not substitute for a Gas Safe notification. If you have installed or replaced an appliance, that work must be notified to Gas Safe Register separately. The CP12 is the annual or periodic safety check record, usually required for rented properties, and it has its own legal framework and its own penalties for non-compliance.
Legal Requirements: Who Must Have One and When
Under Regulation 36 of the Gas Safety (Installation and Use) Regulations 1998, every landlord who lets a property containing gas appliances, pipework, or flues must have those appliances checked by a Gas Safe registered engineer at intervals not exceeding 12 months. The engineer must issue a written Gas Safety Record after every check. The landlord must give a copy to the existing tenant within 28 days of the check, and to any new tenant before they move in.
Landlords must also keep a copy of each record for at least two years. The duty to carry out the check, and the duty to provide the record, fall on the landlord, but the duty to produce a complete and accurate record falls squarely on you, the engineer. If you issue an incomplete or incorrect certificate, you have not fulfilled your professional obligation under the Regulations, and you may have exposed both yourself and your client to enforcement action.
Owner-occupiers are not legally required to hold a CP12 for their own home, but many mortgage lenders and insurers ask for one. Some letting agents and housing associations also require certificates outside the strict statutory minimum. As a registered engineer, the standard of documentation you produce should be identical regardless of whether the job is legally mandated or requested voluntarily.
- •Regulation 36(3)(a): landlord must ensure a check is carried out at intervals not exceeding 12 months
- •Regulation 36(3)(b): a record of the check must be made by the engineer
- •Regulation 36(4): landlord must provide a copy to the existing tenant within 28 days
- •Regulation 36(5): landlord must provide a copy to a new tenant before occupation
- •Regulation 36(6): landlord must retain records for at least two years
Every Field on the Certificate Explained
The Gas Safety (Installation and Use) Regulations 1998 do not prescribe a fixed form, but Gas Safe Register's guidance sets out the minimum information that must appear on every valid record. Missing any of these fields means the certificate is incomplete, and an incomplete certificate is not a valid legal record. Below is a field-by-field breakdown of what to include and why each one matters.
The engineer details section must include your full name, your Gas Safe Register number, and the business name and address you are trading under. Your Gas Safe number allows the landlord, tenant, or the Health and Safety Executive to verify your current registration. If your registration has lapsed, even a technically accurate certificate has no legal standing.
The property address must be complete and unambiguous. Flat numbers, floor levels, and building names all need to be present. You would be surprised how many disputes arise because an address on a certificate does not match the address on a tenancy agreement. Date of inspection is the actual date you were on site, not the date you issue the record.
- •Engineer name, Gas Safe Register number, and business address
- •Full property address including flat or room number
- •Date of inspection
- •Description, make, model, and location of each appliance inspected
- •Appliance type (e.g. boiler, gas fire, hob, back boiler)
- •Flue type and condition
- •Safety devices checked (e.g. flame supervision device, over-heat thermostat)
- •Operating pressure and heat input (where applicable and accessible)
- •Ventilation adequate: Yes or No
- •Safety check result for each appliance: SAFE, AT RISK (AR), or IMMEDIATELY DANGEROUS (ID)
- •Action taken where AR or ID is recorded
- •Whether the landlord has been informed of any defects
- •Engineer signature
- •Next inspection due date
Understanding the Three Safety Outcomes
Every appliance you inspect must be classified into one of three outcomes: SAFE, AT RISK (AR), or IMMEDIATELY DANGEROUS (ID). Getting this classification wrong is not a paperwork error, it is a competence issue that can result in disciplinary action by Gas Safe Register and, in the event of harm, a criminal prosecution under the Health and Safety at Work etc. Act 1974.
An appliance recorded as SAFE means it passed all checks and is fit for continued use. An AT RISK classification means the appliance presents a risk but is not in immediate danger of causing death or serious injury. In most cases you should advise the landlord and tenant in writing that the appliance should not be used until the defect is rectified, and you should record the advice given on the certificate itself.
An IMMEDIATELY DANGEROUS classification means the appliance must be taken out of service immediately. You must inform the occupant, and ideally the landlord, that the appliance is not to be used. You should disconnect or cap off the supply where it is safe to do so, and you must record every action taken on the certificate. Issuing a certificate without accurately recording an ID or AR outcome is a serious professional and legal failure.
Common Mistakes That Invalidate a Certificate
The most frequent error is leaving fields blank or writing 'N/A' without justification. If a boiler has no accessible data plate and you cannot confirm the model number, write that explanation in the notes field. A blank field with no explanation looks like an incomplete inspection, not an inaccessible appliance.
A second common mistake is recording the wrong Gas Safe Register number, particularly if you have recently renewed your registration or if you work under a contractor's umbrella for some jobs and sole-trader for others. Your Gas Safe number on the certificate must match the number that was current on the date of inspection. Issuing a certificate under a registration number that belongs to another engineer, even your employer, is a notifiable offence.
A third mistake is failing to list every gas appliance in the property. If a property has a boiler, a gas hob, and a gas fire, all three must appear on the certificate. Inspecting only the boiler and issuing a certificate that gives the impression all gas appliances have been checked is misleading at best and potentially dangerous. If you were denied access to an appliance, record that denial on the certificate.
- •Blank fields with no explanation
- •Incorrect or expired Gas Safe Register number
- •Missing appliances not listed on the record
- •Date of issue used instead of date of inspection
- •No signature from the engineer
- •AR or ID outcomes recorded without noting the action taken
- •Incorrect property address
- •Next inspection date omitted
Penalties for Non-Compliance
Under the Gas Safety (Installation and Use) Regulations 1998, failure to carry out the annual check or to provide a valid record is a criminal offence. A landlord can be prosecuted and, on summary conviction, fined up to £6,000 per offence. In the most serious cases, where a failure leads to injury or death, prosecution under the Health and Safety at Work etc. Act 1974 Section 33 can result in an unlimited fine and up to two years' imprisonment.
For you as the engineer, issuing a knowingly false or incomplete certificate is a disciplinary matter with Gas Safe Register, which can result in the suspension or removal of your registration. Without registration, you cannot legally carry out gas work in the UK. A lost registration is effectively a lost livelihood, and Gas Safe Register does act on complaints from landlords, tenants, and the HSE.
It is worth noting that the HSE actively investigates carbon monoxide incidents and will trace the certificate trail. If an incident occurs at a property where you issued a CP12 in the past 12 months, your paperwork will be examined. A certificate that was technically accurate but incomplete in its documentation offers you much less protection than one that was thorough and clearly signed off.
Worked Example: A Completed Gas Safety Record
Below is a fully worked example of a completed Gas Safety Record for a typical two-bedroom rented flat. Every field is populated as it would be on a real job. You can use this as a direct reference when completing your own certificates.
Use this example as a checklist. If any field on your own certificate is blank and is not explained in the notes, treat that as an error to correct before the record leaves your hands.
- •LANDLORD NAME: Mr D. Patel
- •LANDLORD ADDRESS: 14 Broad Street, Birmingham, B1 2HQ
- •PROPERTY ADDRESS: Flat 3, 22 Acacia Road, Birmingham, B12 8LT
- •DATE OF INSPECTION: 14 June 2025
- •ENGINEER NAME: James Whitfield
- •GAS SAFE REGISTER NUMBER: 123456
- •TRADING NAME: Whitfield Gas Services
- •BUSINESS ADDRESS: 7 Forge Lane, Solihull, B91 2NT
- •--- APPLIANCE 1 ---
- •APPLIANCE TYPE: Combination Boiler
- •MAKE / MODEL: Ideal Logic+ 30
- •LOCATION: Airing cupboard, first floor
- •FLUE TYPE: Room-sealed, balanced flue (C-type)
- •FLUE CONDITION: Satisfactory
- •OPERATING PRESSURE: 18 mbar
- •HEAT INPUT: 30 kW (confirmed from data plate)
- •VENTILATION ADEQUATE: Yes
- •FLAME SUPERVISION DEVICE: Tested, functioning correctly
- •VISUAL CONDITION: Good, no signs of incomplete combustion
- •SAFETY CHECK RESULT: SAFE
- •--- APPLIANCE 2 ---
- •APPLIANCE TYPE: Gas Hob
- •MAKE / MODEL: Hotpoint GC641IX
- •LOCATION: Kitchen
- •FLUE TYPE: Open-flued (no flue required for hob)
- •VENTILATION ADEQUATE: Yes, extractor fan present and functional
- •VISUAL CONDITION: Burner crowns clean, no blockages observed
- •SAFETY CHECK RESULT: SAFE
- •--- APPLIANCE 3 ---
- •APPLIANCE TYPE: Gas Fire
- •MAKE / MODEL: Valor Inspire 2 (inset)
- •LOCATION: Living room
- •FLUE TYPE: Open-flued, class 1 chimney
- •FLUE CONDITION: Visual inspection satisfactory, draw test completed
- •VENTILATION ADEQUATE: Yes, permanent ventilation present
- •FLAME SUPERVISION DEVICE: Tested, functioning correctly
- •SAFETY CHECK RESULT: AT RISK (AR) - spillage indicated on draw test
- •ACTION TAKEN: Landlord advised verbally and in writing that appliance should not be used until chimney is swept and re-tested. Written notice provided to landlord (Mr D. Patel) on date of inspection. Appliance not disabled as access to gas valve is within landlord's remit; written advisory issued.
- •LANDLORD INFORMED OF DEFECTS: Yes, by telephone at 14:30 and confirmed in writing
- •NEXT INSPECTION DUE: 14 June 2026
- •ENGINEER SIGNATURE: J. Whitfield
- •DATE OF ISSUE: 14 June 2025
How to Issue and Store the Certificate Correctly
Once the certificate is complete and signed, you must provide a copy to the landlord. If the tenant is present at the time of inspection, it is good practice to give them a copy on the same day, which satisfies the landlord's obligation under Regulation 36(4) and saves an administrative step. If the tenant is not present, make sure the landlord understands the 28-day window for delivery.
For your own records, keep a copy of every certificate you issue for a minimum of two years. This is the minimum period specified under the Regulations, but in practice it makes sense to keep records for longer given that the Limitation Act 1980 allows civil claims to be brought up to six years after an event. A physical file works, but a searchable digital archive is far more practical when you need to find a specific record quickly.
If you issue the certificate digitally, the signature must still be present. A typed name alone is not sufficient. A digital signature or a scanned wet signature both satisfy the requirement. If you use a PDF template, ensure the file is locked after completion so that fields cannot be altered by a third party after issue.
A Note on Gas Tightness Testing and IGEM/UP/1B Edition 4
While a routine CP12 annual inspection does not typically require a full gas tightness test, any CP12 that follows installation work or where a concern about pipework integrity exists will involve one. From 1 October 2026, IGEM/UP/1B Edition 4 changes how acceptable pressure drop is determined during tightness testing. Under the new edition, the permissible pressure drop during a let-by test is determined by the installation volume rather than by meter size, and any perceptible movement on the gauge is no longer attributable to the installation pipework.
This is a material change if you carry out tightness tests as part of any gas safety work, whether that is pre-completion commissioning, fault-finding, or a post-repair check. If your current working method relies on the meter-size-based tables from the previous edition, you need to update your practice before October 2026. The certificate you issue after a tightness test should reference the standard you tested to, which from that date must be IGEM/UP/1B Edition 4.
The routine annual landlord inspection CP12 does not require a tightness test unless there is a specific reason to carry one out, such as a smell of gas, a reported appliance fault, or visible pipework damage. If you do carry one out as part of the inspection, record it on the certificate with the result.
Choosing Between a Paper Template and a Digital Tool
A paper template is fine if you are doing a handful of CP12s a year and have a reliable system for filing copies. Download or print the template from this page, fill it in on site, scan or photograph it, and email copies to the landlord and yourself. The risk with paper is illegibility, lost copies, and the time it takes to retype details that should already be in your records.
A digital template, whether that is a fillable PDF, a Word document, or a purpose-built tool, solves the legibility problem and makes storage and retrieval far more straightforward. The fields are fixed, so you are less likely to miss one by accident. If you email the certificate from a digital tool, you have a built-in timestamp and delivery record, which is useful if a landlord ever disputes whether they received the certificate within the 28-day window.
TradeDoc AI generates a compliant Gas Safety Record in about two minutes. It is free for your first 100 documents a month, no card required at sign-up, and all four UK trades are covered in one place. If you want your logo on the PDF and one-tap email send to the customer, Pro is £15 per month. You can find it at tradedoc.co.uk.
