What Is a Gas Safety Certificate (CP12)?
A Gas Safety Record — commonly called a CP12 (the reference number of the original documentation standard) — is the document issued by a Gas Safe registered engineer after completing a gas safety inspection of the gas appliances and pipework in a property. It confirms that all inspected appliances are operating safely, with combustion readings within acceptable limits, and that the installation does not pose a risk to occupants.
The CP12 records:
- The appliances inspected (boiler, gas fires, cookers, etc.)
- Whether each appliance has passed or failed the safety check
- Any defects found and whether they were rectified at the time
- The engineer's Gas Safe registration number and signature
- The date of inspection and expiry date (12 months from inspection)
Only a Gas Safe registered engineer can carry out a gas safety inspection and issue a CP12. Verify any engineer at gassaferegister.co.uk. A CP12 from an unregistered person has no legal standing and exposes the property owner to significant legal and financial risk.
Why It Is a Legal Requirement for Landlords
For residential landlords, an annual gas safety check is not optional — it is a legal obligation under the Gas Safety (Installation and Use) Regulations 1998 (Regulation 36). The law requires that:
- All gas appliances and flues in rental properties are checked for safety every 12 months
- The check must be carried out by a Gas Safe registered engineer
- Landlords must keep records of each gas safety check for a minimum of two years
- Landlords must provide a copy of the most recent gas safety record to existing tenants within 28 days of the check being completed, and to new tenants before they move in
- Landlords must not let a property without a valid, in-date gas safety record
The penalties for non-compliance are severe. Under the Health and Safety at Work etc. Act 1974 and the Gas Safety Regulations, landlords who fail to comply face:
- An unlimited fine
- Up to 6 months' imprisonment
- Civil liability if a tenant or visitor is harmed as a result of an unsafe gas appliance
- Difficulty enforcing possession proceedings — courts have refused landlords' Section 21 possession notices where a valid CP12 was not provided to tenants
Homeowners (as opposed to landlords) are not legally required to have an annual gas safety check, but it is strongly recommended as good practice for the safety of everyone in the home.
What Is Checked During a CP12 Inspection?
A thorough gas safety inspection covers all gas appliances in the property. For a typical domestic property, this includes:
- Boiler — Combustion analysis (checking for carbon monoxide and ensuring the flue is working correctly), gas pressure checks, heat exchanger integrity, burner condition, controls operation, and safety device testing
- Gas fires — Combustion analysis, flue pull test (checking the flue draws properly), burner condition, and safety controls
- Gas cooker or hob — Burner condition, ignition operation, and gas pressure
- Other gas appliances — Any gas tumble dryer, gas room heater, or gas water heater present in the property
- Gas meter and pipework — Tightness test on the gas installation to check for leaks; visual inspection of visible pipework and connections
- Flues and ventilation — Checking that flues are unobstructed, correctly installed, and properly venting combustion gases outside the property
The inspection typically takes 30 to 60 minutes for a standard property with a boiler and one or two additional appliances. Properties with more gas appliances or complex installations take longer.
After inspection, the engineer issues the CP12 on the spot (or sends it electronically shortly after). The document must clearly state Pass or Fail for each appliance. If any appliance fails, the engineer will either carry out remedial work immediately (if possible and if you agree to the additional cost) or issue a warning notice and advise you on next steps.
Cost of a Gas Safety Certificate in 2026
The cost of a CP12 gas safety check varies by location, the number of appliances being inspected, and the engineer or company you use:
| Region / Situation | Typical CP12 Cost |
|---|---|
| UK average (boiler only) | £60 – £90 |
| UK average (boiler + 1 gas fire or cooker) | £70 – £100 |
| UK average (multiple appliances) | £80 – £120 |
| London / South East | £80 – £130 |
| Combined with annual boiler service | £90 – £140 |
Many landlords combine the annual gas safety check with the boiler's annual service, which is more cost-effective than booking them separately. A combined service and CP12 from a single engineer typically saves £20 to £40 compared to separate bookings.
Be cautious of unusually low advertised prices (under £45–£50). Very cheap CP12 checks sometimes reflect rushed inspections that do not properly test all appliances — a false economy given the safety and legal stakes involved. Similarly, be wary of engineers who issue CP12 certificates without attending the property.
Landlord CP12 vs Standard Gas Safety Check
The distinction between a "landlord CP12" and a "standard gas safety check" is primarily one of legal obligation rather than technical difference. The actual inspection process is identical — a Gas Safe registered engineer inspecting gas appliances and pipework to the same safety standard.
The key differences relate to the documentation and legal context:
- Landlord CP12 — Issued to satisfy the Gas Safety (Installation and Use) Regulations 1998 for rental properties. The landlord is legally required to provide a copy to tenants and retain records. The document is addressed to and held by the landlord (or property manager).
- Standard gas safety check — Carried out for homeowners (not legally required, but recommended). The same technical inspection, but without the regulatory record-keeping obligation.
Some companies charge a small premium for a landlord CP12 to cover additional documentation and record management. This is typically £5 to £15 above their standard check price and is reasonable. If a company charges substantially more for the "landlord" version than the standard check, it is worth asking what specifically justifies the difference.
For landlords with multiple properties, many gas engineering companies offer multi-property discounts or block-booking rates. If you have 3 or more properties, it is worth asking about portfolio pricing.
How to Find a Gas Safe Engineer for Your CP12
Finding the right engineer for a gas safety inspection involves more than price comparison:
- Gas Safe Register search — The most reliable starting point. Search by postcode at gassaferegister.co.uk/find-an-engineer to find registered engineers near you. You can filter by domestic appliances and verify their specific licensed categories.
- Check the engineer's ID on arrival — Before any gas work begins, ask to see the engineer's Gas Safe ID card. The card includes their licence number, an expiry date, and the specific categories of work they are licensed to carry out. You can also scan the QR code on their card to verify in real time.
- Annual reminder setup — A CP12 is valid for 12 months. Set a reminder one month before the current certificate expires so you can book in advance and avoid a gap in compliance. Some gas engineering companies offer automatic annual reminders or renewal booking for landlords.
- Reviews from landlords specifically — When reading reviews, look for feedback from other landlords and property managers who specifically mention gas safety certificates. An engineer who is reliable, prompt, and issues clear documentation is worth a small premium over one who is cheaper but unreliable.
- Property management companies — If you use a letting agent or property management company, they often have preferred gas engineers. Check whether their preferred engineer's rates are competitive and whether the CP12 is provided directly to you as the landlord.