Why the CP12 exists
The Gas Safety (Installation and Use) Regulations 1998 place an absolute duty on landlords to ensure gas appliances are maintained in a safe condition and inspected annually. The CP12 is the documentary evidence. The regulation exists because faulty gas appliances kill — carbon monoxide poisoning is silent and rapid, and a poorly maintained boiler is a common cause.
What the engineer actually checks
A Gas Safe registered engineer (always check the ID card and registration number) inspects:
- Every gas appliance — boilers, fires, cookers, hobs
- All accessible gas pipework
- Flues and chimneys for safe gas evacuation
- Ventilation provision for the room
- A tightness test on the supply to confirm no leaks
- Operating pressure and combustion performance
Validity, timing and renewal
A CP12 lasts 12 months from the inspection date. The new certificate must be issued before the previous one expires — but you can renew up to 2 months early without losing time on the new one (the new expiry runs from the old expiry date, not the new inspection date). For new tenancies, the CP12 must be in place before move-in. A copy must be provided to the tenant within 28 days of inspection, or before move-in for new tenants.
Fines and legal consequences
Penalties for non-compliance are unlimited and, in serious cases, include imprisonment under HSE prosecution. Beyond fines, landlords without a valid CP12 cannot serve a valid Section 21 notice — meaning you cannot regain possession of your property even if the tenant breaches the lease. Insurance claims for boiler-related damage can be voided if no current CP12 exists.
How much does a CP12 cost in 2026?
Gas Safety Certificates in Greater Manchester start at £75 for a property with one boiler and one cooker/hob. Each additional appliance is added at a published rate. Bundling with EPC and EICR via a Landlord Compliance Package saves £40–£70 versus separate bookings. There is no travel surcharge within the Greater Manchester postcode area.
What happens if an appliance fails
If the engineer finds an immediately dangerous (ID) or at-risk (AR) appliance, they will isolate it on the spot with the tenant's consent and issue a warning notice. You'll receive a written remedial quote — most repairs are minor (faulty thermocouple, blocked flue, perished seal) and can be done on the same visit if parts are stocked.
Common CP12 mistakes landlords make
The most frequent compliance failures are administrative, not technical:
- Forgetting to renew before the 12-month expiry — coverage gaps invalidate Section 21
- Not serving the certificate on the tenant within 28 days
- Failing to keep records for at least 2 years (HSE recommendation)
- Using a non-Gas Safe engineer (always verify on the Gas Safe register)