Landlord Gas Safety Certificate (CP12) — UK Requirements Explained 2026
The Landlord Gas Safety Record — historically known as the CP12 — is the single most important compliance certificate a UK landlord with gas appliances needs to hold. Missing one is a criminal offence and automatically invalidates a Section 21 eviction notice. This guide covers the legal requirements in 2026, what an inspection actually involves, how to find a registered engineer and what to do if a property fails.
Quick summary: Every UK landlord with gas appliances must have a Gas Safe registered engineer inspect them every 12 months and provide tenants with a copy of the certificate within 28 days (or before move-in for new tenants). Penalty for failure: unlimited fine, up to 6 months in prison and an invalidated Section 21. Typical cost: £60–£120.
The legal requirement
The Gas Safety (Installation and Use) Regulations 1998 (as amended) set out a landlord's duties:
- Maintain all relevant gas fittings (pipework, appliances, flues) in a safe condition
- Arrange annual safety checks (intervals not exceeding 12 months) by a Gas Safe registered engineer
- Keep records of each safety check for a minimum of 2 years
- Issue a copy of the latest record to existing tenants within 28 days of the inspection
- Issue a copy to new tenants before they take occupation
The regulations apply to all rented residential property in the UK where the landlord owns gas appliances. If the property has no gas appliances (electric only) the regulations don't apply — but if any single gas appliance is present, the full duties kick in.
What's actually inspected?
The Gas Safe engineer checks every gas appliance owned by the landlord, plus the supply pipework:
For each appliance
- Operating pressure — measured at the inlet to verify supply is correct
- Heat input / heat output — to check the appliance is running within manufacturer's spec
- Combustion performance — flue gas analysis where applicable
- Flue and ventilation — checking the flue isn't blocked and there's adequate ventilation in the room
- Safety devices — flame supervision, oxygen depletion sensor (where fitted), interlocks
- Physical condition — case, controls, gas valves, seals
- Stability — appliance correctly fitted and not damaged
Pipework
- Gas tightness test on the supply pipework
- Visual inspection of accessible pipework for damage or corrosion
- Verification of correct emergency control valve labelling
The engineer issues a Landlord Gas Safety Record (LGSR/CP12) listing every appliance, its location, the test results and any defects identified.
⚠ Important distinction: A gas safety inspection is NOT a boiler service. The two are different. The CP12 confirms safety; the service includes cleaning, parts replacement and longer-term maintenance. Many engineers offer combined "service + CP12" at £100–£150 — which is sensible if your boiler isn't already covered by a separate warranty/service plan.
What's checked vs not checked
| Item | Included in CP12? |
|---|---|
| Boiler safety (the landlord's appliance) | Yes |
| Gas hob, oven, fire (landlord's) | Yes |
| Pipework from meter to appliance | Yes |
| Flue and ventilation | Yes |
| Boiler service (cleaning, parts) | No — separate service |
| Tenant's own gas appliances (e.g. portable heaters) | No — tenant responsibility |
| The gas meter and pre-meter pipework | No — National Grid / supplier responsibility |
| Carbon monoxide alarm test | Often included, but technically separate |
Finding a Gas Safe registered engineer
Only engineers on the Gas Safe Register are legally allowed to carry out the safety check. To find one:
- Gas Safe Register search: gassaferegister.co.uk — search by postcode, business name or registration number
- Local recommendations: ask your letting agent or local landlord group
- Verify the engineer's card: when they arrive, ask to see their Gas Safe ID card. It shows their photo, registration number, expiry date and the categories of work they're qualified for (e.g. natural gas, LPG)
Each engineer holds qualifications for specific work types. For example, a domestic natural gas registration doesn't cover LPG or commercial catering. Make sure the engineer's qualifications match your property's appliances.
Typical costs in 2026
| Property type | Typical CP12 only | CP12 + boiler service |
|---|---|---|
| 1-bed flat (boiler only) | £60 – £90 | £100 – £140 |
| 2-bed flat (boiler + hob) | £70 – £110 | £110 – £160 |
| 3-bed house (boiler + hob + fire) | £80 – £130 | £120 – £180 |
| HMO with multiple appliances | £100 – £180+ | £150 – £250+ |
| London / SE premium | +20–40% | +20–40% |
Avoid suspiciously cheap quotes (£40 for a 3-bed CP12 is often a hook for upsell on remedial work). And avoid engineers who can't provide their Gas Safe registration number — that's a regulatory red flag.
When does the 12-month clock start?
The 12-month interval runs from the date of inspection — not the date the certificate was issued, not the tenancy start, not when you handed the certificate to the tenant. If the previous inspection was 15 March 2025, the next must happen by 15 March 2026 (you have a small grace built in: HSE guidance is that you can carry out the next inspection within 2 months of the expiry without resetting the cycle, so up to 15 May 2026 with the new date counted as 15 March 2026 for the next year's cycle).
✓ OwnProperly tip: Don't run to the wire. Book the inspection 4–6 weeks before expiry. Gas Safe engineers are often booked solid during autumn (when boilers are first being used after summer) and many landlords leave it too late. A missed deadline is an unlimited fine waiting to happen.
Penalties for non-compliance
The penalties for failing to comply with the Gas Safety (Installation and Use) Regulations are among the harshest in landlord law:
- Unlimited fine on conviction
- Up to 6 months in prison (in the most serious cases — particularly where injury or death has resulted)
- Both can be imposed
- Invalidated Section 21 notice — under the Deregulation Act 2015 you cannot serve a valid no-fault eviction notice unless a current and historic gas safety record has been served on the tenant. See our Section 21 guide
- Civil liability in the event of a CO leak or gas incident
- Reputational damage — gas-related convictions are widely publicised
Several landlords have served custodial sentences over the past decade where tenant injury or death resulted from missing or fraudulent CP12s. This is genuinely the highest-stakes compliance item a landlord faces.
What if your property fails the gas safety inspection?
If the engineer identifies safety defects, they will record them on the LGSR/CP12 and may take action depending on severity:
- At Risk (AR): appliance has a fault that could cause injury but isn't immediately dangerous. Engineer will recommend remedial work and the landlord must fix promptly
- Immediately Dangerous (ID): appliance presents immediate risk of injury. Engineer will offer to disconnect (with your permission). Must be repaired before being used again
- Not to Current Standards (NCS): not strictly dangerous but not compliant with current standards. Improvement recommended but not legally required
If an appliance is disconnected as "Immediately Dangerous", you must arrange repair or replacement before the property is occupied. Tenant safety overrides any commercial inconvenience.
Documenting and serving the certificate
- Receive the CP12 PDF from the engineer (most send digitally; some still issue paper)
- Save with your property records — many landlords use a dedicated folder per property
- Within 28 days of inspection (or before new tenant move-in), send the certificate to the tenant. Email is fine if the tenant has agreed to electronic communication
- Keep evidence the tenant received it — email read receipt, tenant portal acknowledgement, or signed confirmation
- Diarise the next inspection date — typically 11 months ahead to give buffer for booking
⚠ Section 21 trap: To serve a valid Section 21 notice you must show the tenant received the gas safety certificate before they moved in. The Court of Appeal's decision in Trecarrell House v Rouncefield (2020) clarified that late provision of a CP12 mid-tenancy can be cured for the purposes of serving Section 21 — but pre-tenancy delivery is the safer default.
Multi-let / HMO landlords
If you let an HMO, the gas safety duties apply across the whole property. The single CP12 covers all the landlord's gas appliances in the property. Tenants of individual rooms should each receive a copy on or before move-in.
HMOs frequently have more appliances (multiple hobs, central heating boiler, gas fire in lounge) and inspections cost more. Combined service + CP12 deals make particular sense for HMOs given the higher appliance count.
Gas safety certificate checklist
- Engineer's Gas Safe ID checked before work starts
- All landlord-owned gas appliances inspected and listed on the CP12
- Pipework gas tightness test recorded
- Any AR/ID defects remedied and re-certified
- CP12 stored digitally with property records
- Copy served on every tenant within 28 days (or before move-in)
- Evidence of tenant receipt retained
- Next inspection date diarised at 11 months
Never miss a gas safety renewal
OwnProperly's compliance tracker stores every CP12, alerts you at 90, 60 and 30 days before expiry, and records evidence of delivery to each tenant. One missed certificate can cost five figures in fines or invalid evictions.
Start free trial — no card neededHow OwnProperly Helps
The CP12 cycle is one of the easiest things in landlord life to miss — and the consequences are the worst. OwnProperly's compliance tracker logs each gas safety certificate with its issue date, expiry date and the engineer's Gas Safe registration number, then triggers email alerts at 90, 60 and 30 days. Tenant delivery is logged via the tenant portal so you have proof of service if challenged on a future Section 21.
Related reading: UK landlord compliance checklist, EICR cost guide, Section 21 notices.