A definitive guide to your CP12 obligations as a London landlord, written by Gas Safe registered engineers who issue dozens of these every week. Covers the legal framework, what's tested, what it costs, deadlines, exemptions, penalties, and how to handle the difficult cases.
What is a CP12?
A CP12, formally called a Landlord's Gas Safety Record, is the certificate issued annually by a Gas Safe Registered engineer confirming that all the gas appliances, gas pipework and flues in a rented property are safe to use. The document records each appliance individually, the gas pressure tests carried out, the combustion analysis results, and any defects found and how they were classified.
"CP12" is the historical name from the original British Gas certificate template, which has stuck colloquially even though the modern document follows the Gas Safe Register's standardised format.
Is a CP12 a legal requirement?
Yes, absolutely. The legal duty arises under Regulation 36 of the Gas Safety (Installation and Use) Regulations 1998, which imposes a duty on landlords to:
- Ensure gas fittings and flues are maintained in a safe condition;
- Have an annual safety check carried out by a Gas Safe Registered engineer;
- Provide tenants with a copy of the most recent CP12 within 28 days of the check (and to new tenants before they move in);
- Retain copies for at least 2 years.
Failure to comply is a criminal offence, punishable by unlimited fines and, in cases of injury or death from gas exposure, custodial sentences for landlords and managing agents.
Which properties need a CP12?
Any property that is rented out (assured shorthold tenancy, assured tenancy, regulated tenancy, holiday let, HMO, lodger arrangement) and contains any gas appliance, boiler, gas hob, gas oven, gas fire, gas water heater. The duty applies to:
- Buy-to-let landlords (any number of properties)
- Letting agents managing on behalf of landlords
- HMO licence-holders
- Local authorities and housing associations renting out properties
- Holiday-let owners (Airbnb, short-stay)
- Companies leasing residential property to staff
The duty does not apply to properties without any gas appliances (electric-only properties), or to owner-occupiers (who are nevertheless strongly recommended to have annual gas safety checks).
What does the engineer actually check?
Per the Gas Safe Register / ACS standard, the inspection includes:
- Visual inspection of every gas appliance
- Combustion gas analysis (FGA), measuring CO and CO₂ levels
- Operating gas pressure verification
- Tightness test of the gas pipework (BS 6891 standardised pressure decay test)
- Flue integrity check, adequate ventilation, no blockages, no spillage
- Safety device functionality (flame supervision device, oxygen-depletion sensor, overheat thermostat)
- Stability and clearances of the appliance
Any defect identified is classified per Gas Safe guidance:
- Immediately Dangerous (ID), appliance must be isolated and labelled, not used until repaired/replaced.
- At Risk (AR), fault that doesn't immediately endanger safety but should be rectified soon. Customer's permission required to leave in service.
- Not to Current Standards (NCS), installation doesn't meet current standards but isn't unsafe. Recorded for awareness.
How often must a CP12 be renewed?
Annually. The certificate expires 12 months from the date of inspection (not from the date of issue). You can renew up to 2 months before expiry without affecting the renewal date, useful for managing portfolios with rolling renewals.
Missing the renewal date by even a single day means non-compliance, your tenants are technically renting an uncertified property, and you're exposed to criminal liability. We strongly recommend setting calendar reminders 30 days before expiry, and using a reminder service if you have multiple properties.
What does a CP12 cost in London?
| Inspection Type | Typical Cost |
|---|---|
| Single boiler property | £79 + VAT (£125 inc VAT) |
| CP12 + annual boiler service combined | £149 + VAT (£210 inc VAT) |
| Multi-appliance property (boiler + cooker + fire) | £99 + VAT (£118.80 inc VAT) |
| HMO multi-appliance inspection | £20,40 per additional appliance over base price |
| Multi-property landlord package (10+ properties) | From £45 + VAT per property (volume discount) |
Combined CP12 + boiler service represents the best value because it satisfies both the legal duty and the manufacturer warranty requirement (which typically requires annual servicing).
How long does the inspection take?
For a single-boiler property, typically 30,45 minutes. Multi-appliance properties (boiler + cooker + fire + water heater) typically 60,90 minutes. HMO properties with bedsit-style separate gas meters can take half a day.
What about tenant access?
You must give tenants reasonable notice and access to comply with your CP12 duty, but the Regulation specifically states that a tenant's refusal to allow access does not relieve you of the duty. You must:
- Make multiple documented attempts to arrange access (in writing, keep records)
- Where access continues to be refused, seek a court injunction for access
- Document everything, your evidence of attempted compliance is your only defence in the event of an HSE prosecution
Penalties for non-compliance
Penalties under the Gas Safety (Installation and Use) Regulations 1998 are severe:
- Unlimited fines at Crown Court for serious breaches
- Up to 6 months' imprisonment for breach of regulations leading to risk of injury
- Manslaughter charges where death results from gas-related causes (multiple landlord prosecutions on record)
- Section 21 invalidation, non-compliant landlords cannot serve a Section 21 (no-fault) eviction notice
- Civil claims from tenants for breach of duty of care
- HMO licence revocation by local authorities
- Insurance claims voided in the event of any gas-related incident
The Health and Safety Executive (HSE) has prosecuted dozens of London landlords in recent years, with fines ranging from £2,000 to £500,000+ depending on circumstances and whether harm occurred.
What other certificates do London landlords need?
The CP12 is just one of several mandatory landlord certificates:
- Energy Performance Certificate (EPC), every 10 years. Minimum E rating for new tenancies (was extended to existing tenancies in 2020); minimum C from 2028 (proposed).
- Electrical Installation Condition Report (EICR), every 5 years. Mandatory under Electrical Safety Standards Regulations 2020.
- Smoke alarm + CO alarm compliance, Smoke and Carbon Monoxide Alarm (England) Regulations 2022; alarm in every storey, CO alarm in every room with combustion appliance.
- Legionella risk assessment, recommended best practice. Mandatory under Health and Safety at Work Act for HMOs.
- How to Rent guide, must be provided to tenants at start of tenancy (latest government version).
- Tenancy Deposit Protection, deposit must be protected within 30 days of receipt.
- Right to Rent check, immigration status verification on all adult tenants.
HMO-specific requirements
If your property is licensed as an HMO (House in Multiple Occupation), typically 5+ unrelated tenants forming 2+ households, additional gas safety requirements apply:
- Each gas appliance in shared use must be inspected (kitchen hob, water heater, central heating boiler)
- Each room with a combustion appliance must have a CO alarm
- HMO licence renewals (typically every 5 years) require evidence of continuing CP12 compliance
- Some London boroughs require an HMO-specific Multi-Appliance Gas Safety Certificate, which we issue routinely
What landlords commonly get wrong
- Letting the certificate lapse, the calendar runs the day after the previous inspection date, not from when you remembered.
- Not giving the certificate to tenants, you must give a copy within 28 days of the check, and to new tenants before they move in. Email is fine. Keep proof of delivery.
- Using an unregistered "Gas Safe" engineer, always verify the engineer's ID at gassaferegister.co.uk. The Gas Safe Register publicises convicted unregistered engineers.
- Ignoring "At Risk" findings, even AR findings need to be rectified at next reasonable opportunity. Documented refusal to fix can be used against you in any subsequent prosecution.
- Forgetting holiday lets, Airbnb and short-stay properties are still rented properties and require CP12s.
- Assuming the tenant's gas appliance is exempt, only tenant-owned, tenant-installed cookers connected via a flexible bayonet are exempt from CP12. Anything connected by rigid pipework is your responsibility.
Our landlord packages
For London landlords with one or more rental properties, we offer bundled packages that combine CP12 with other compliance and routine maintenance, saving cost and reducing the admin burden:
- Reactive (£0/month): ad-hoc CP12 at £79+VAT per property, standard rates for repairs
- Standard (£35/month): Annual CP12 + annual boiler service + 10% off labour + priority dispatch
- Premium (£75/month): Above plus 5-yearly EICR, annual PAT testing, Legionella risk assessment, free smoke/CO alarm checks, 20% off labour
FAQ
Can I do my own CP12 if I'm Gas Safe registered?
How quickly can you do a CP12 in London?
What if the engineer finds a fault and the appliance has to be condemned?
Do I need a CP12 for an electric-only property?
Can the CP12 be combined with the annual boiler service?
Need a CP12 in London? Same-day or next-day across all M25 postcodes. Call 020 8050 5306 or book online →