The Ultimate Gas Safety Certificate Checklist
Every landlord letting a property with gas in it needs a valid gas safety certificate, renewed every twelve months. Officially it is a Landlord Gas Safety Record; almost everyone still calls it a CP12, after the old form number. It proves a Gas Safe registered engineer has examined every relevant appliance, flue and length of pipework and found it safe to use.
What a Gas Safety Certificate Is, and What It Is Not
A gas safety certificate is the record issued after an annual safety check of the gas installation in a rented property. It is a snapshot: on the day of the visit, each appliance you provide was operating safely, the pipework held pressure, and combustion products were leaving the building as designed.
The distinction that catches people out is between a safety check and a service. A service is manufacturer-specified maintenance for one appliance; a check confirms that appliance is safe to operate now. Only the check is required by law before you let, though most landlords book both on one visit.
A gas safety certificate covers gas and nothing else. An EICR is required at least every five years under the Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020, which have applied to all existing tenancies since 1 April 2021, and a council can impose a financial penalty of up to £30,000 for a breach. An EPC is needed to market a property, lasts ten years, and the MEES minimum band for letting is E. Proposals to raise that minimum band have been consulted on but are not settled law, so check GOV.UK for the current position. Our landlord safety certificates checklist shows how the documents fit together.
Landlord Duties Under the Gas Safety (Installation and Use) Regulations 1998
The duty to hold a current gas safety certificate comes from the Gas Safety (Installation and Use) Regulations 1998. If you let a property containing gas appliances, pipework or flues, you are responsible for:
- An annual safety check on every gas appliance and flue you provide for the tenant’s use, at intervals of no more than twelve months.
- Maintenance of the pipework, appliances, chimneys and flues you are responsible for.
- Using a Gas Safe registered engineer for the check and any gas work that follows it.
- Keeping the record of each safety check for at least two years.
- Issuing that gas safety certificate to tenants within the timescales set out below.
Enforcement sits with the Health and Safety Executive, whose guidance on landlords’ responsibility for gas safety puts the duty in the regulator’s own words.
Which appliances are yours, and which are the tenant’s
The test is provision rather than ownership. Boilers, hobs, ovens, gas fires and water heaters supplied with the property are yours, along with the pipework running to them and their flues. A cooker the tenant brings in sits outside your gas safety certificate, but the connecting pipework and any flue serving it normally do not, and the engineer will inspect them. A good engineer will still flag an obviously dangerous tenant-owned appliance.
Only a Gas Safe Engineer Can Issue a Gas Safety Certificate
No other qualification substitutes. A general plumber, an installer whose registration has lapsed, or a capable DIY landlord cannot lawfully carry out gas work or produce the record. Registration is also split by category: an engineer registered for domestic boilers is not automatically registered for gas fires, commercial catering equipment or LPG.
How to verify an engineer’s registration
- Ask for the ID card at the door — photograph, licence number, start and expiry dates, security hologram.
- Turn it over. The reverse lists the categories of work the engineer is qualified for. Match those to the appliances in your property.
- Check the expiry date. Registration lapses, and a card that ran out last month evidences nothing.
- Confirm the number independently through the Gas Safe Register’s own search, rather than relying on the card alone.
A record produced by someone who was not registered is not a valid gas safety certificate, however convincing the document looks.
What the Engineer Tests, and What Goes on the Record
A gas safety certificate inspection follows a consistent sequence. Knowing it lets you read the paperwork rather than simply file it.
Gas tightness test
The engineer isolates the installation at the meter and watches the pressure to confirm there is no escape in the pipework. It comes first: a leak halts everything else until it is traced and repaired.
Standing pressure, working pressure and gas rate
Standing pressure is measured with nothing running, working pressure with appliances under load; together they show whether the supply and meter regulator are delivering gas within range and the pipework is sized for the demand. Each appliance is then checked to confirm it is burning the correct volume of gas for its rated output, by burner pressure reading or by timing consumption at the meter. An appliance running outside its designed range wastes fuel and, at the extreme, produces carbon monoxide.
Ventilation
Combustion needs air. Permanent ventilation openings — air bricks, wall vents and purpose-provided grilles — are measured against the requirement for the appliances in that room and checked for obstruction. Blocked vents are among the most common failure points, usually appearing after redecoration or new furniture.
Flue flow and spillage testing
A flue flow test confirms the flue is clear and drawing properly. A spillage test then verifies that combustion products leave the building rather than escaping into the room, carried out with extractor fans running to simulate worst-case conditions. Flue routes concealed in ceiling voids need inspection hatches.
Appliance condition and safety devices
Each appliance is examined for secure fixing, condition of case seals and heat exchanger, and correct operation of flame supervision devices — the mechanism that shuts the gas off if the flame goes out.
What the CP12 record contains
Your gas safety certificate shows the property address and the landlord or agent, the date of the check and the next due date, a line for each appliance with its make, model and location, the results above, any defect found and the action taken, and the engineer’s name, signature and Gas Safe registration number. An appliance that could not be tested because it was inaccessible is recorded as such. Alarms sit alongside this: a carbon monoxide alarm is required in any room used as living accommodation containing a fixed combustion appliance, and our guide to smoke and carbon monoxide alarm rules has the detail.
When an Appliance Is Classed Unsafe
Where the engineer finds a problem, it is classified under the gas industry’s standard unsafe situations procedure, and the classification decides what happens next.
- Immediately Dangerous (ID) — an immediate danger to life or property. The engineer will seek permission to disconnect and cap the appliance, label it and leave a warning notice.
- At Risk (AR) — one or more defects that could become dangerous. Again the engineer will ask permission to turn the appliance off and label it, and it should stay off until the fault is corrected.
- Not to Current Standards (NCS) — not dangerous, but short of today’s standards, often because it complied when installed. It is advisory and does not stop a gas safety certificate being issued, though it is worth planning work around.
Getting back to a valid record
Remedial work must be done by a Gas Safe registered engineer and the appliance retested. Keep the warning notice, the repair invoice and the reissued gas safety certificate together; that sequence shows you responded promptly. Our guide on an unsatisfactory EICR explains the parallel process on the electrical side, where C1, C2 and FI codes make a report unsatisfactory and remedial work is due within 28 days.
Issuing Your Gas Safety Certificate, Renewal and Access
Giving the record to tenants
- Existing tenants: a copy within 28 days of the check being completed.
- New tenants: a copy at the start of the tenancy, before they take occupation.
- Your own file: keep every record for at least two years.
HSE guidance on gas safety check records and what to keep covers record-keeping in detail. Serving the document matters for possession too: our guide to Section 21 and safety certificates explains why the paper trail is examined so closely. Do not overlook the other documents that travel with a new tenancy — deposit protection and prescribed information, the How to Rent guide, the EPC, and the EICR, which must reach tenants within 28 days of the inspection and the council within 7 days of a request.
Timing your renewal
The regulations allow the check to be carried out in the two months before expiry while keeping the original anniversary date, so booking early costs you no certificate life. Let it lapse and the clock restarts from the new date, leaving a documented gap.
When a tenant refuses access
A tenant declining entry does not suspend the duty and is no defence to it. The law expects you to take all reasonable steps and to be able to prove you did:
- Give written notice of the appointment — 24 hours is the normal minimum — and keep a copy.
- Offer alternative dates, including outside working hours.
- Write after each missed appointment, explaining that the check exists for the tenant’s own safety.
- Keep every letter, email and message in one dated file, and take advice before any further step.
Repeated, documented attempts are what protect you.
Preparing so the visit is not wasted
- Clear access to the boiler, meter, hob, fire and flue terminals, including packed cupboards.
- Confirm the supply is on and, for prepayment meters, that there is credit.
- Unblock air bricks and vents, and move furniture away from them.
- Have last year’s gas safety certificate to hand so advisories can be followed up.
Commercial Premises, Communal Areas and the CP42
Commercial gas work is a different registration category and a different record. Catering equipment, commercial boiler plant and warm air heaters in commercial premises are documented on a CP42 rather than a CP12, and the engineer must hold the relevant commercial qualifications. If you let business premises, arrange a commercial gas safety certificate rather than assuming a domestic engineer can cover it.
Multi-occupied buildings add a second layer. Communal corridors, stairwells and plant rooms fall under the Regulatory Reform (Fire Safety) Order 2005, which requires a current fire risk assessment. HMO requirements — licensing conditions, fire doors, alarm grades and emergency lighting — are set locally and vary noticeably between councils, so confirm the position with your own local authority. Our HMO fire regulations guide covers that ground.
Book Your Gas Safety Certificate in London
Landlord Safety Checks London carries out Gas Safe registered inspections across London and Essex, for single properties and for portfolios on a renewal schedule. We can combine your gas safety certificate with an EICR or PAT testing so tenants are disturbed once.
See what each check costs on our pricing page, book your gas safety certificate online in a couple of minutes, or contact the team on 0208 178 4580 to talk it through first.
Frequently Asked Questions
How long is a gas safety certificate valid for?
Twelve months from the date of the check. The next inspection can be done up to two months early while keeping your original anniversary date.
What happens if an appliance fails the check?
The engineer records the classification and, with permission, disconnects and labels anything Immediately Dangerous or At Risk. Once a Gas Safe registered engineer has corrected and retested the fault, the gas safety certificate is completed and reissued.
Do I need a gas safety certificate with no gas appliances?
If there is no gas supply and no appliances at all, the annual check does not apply. Where a supply is present but capped, ask your engineer, because the pipework may still need assessing.
Can my letting agent hold the gas safety certificate for me?
An agent can arrange the check and hold copies, but agree in writing who books it, who serves the record and who chases access. The duty stays with you as the landlord.
This article is general guidance on gas safety duties in England, not legal advice. Requirements change and local authority conditions vary, so check the current position on GOV.UK or HSE, or with your council, and take professional advice on your own property.