The Landlord Gas Safety Certificate: CP12 vs Service
What a landlord gas safety check covers, why a CP12 is not a boiler service, what drives the price, and what happens when an appliance is failed.
8 min readTeesside Premium
Start here: the duty in plain English
If you let a property with gas in it, the Gas Safety (Installation and Use) Regulations 1998 put four things on you. Every gas appliance and flue you provide must be checked for safety at intervals of no more than 12 months, by a Gas Safe registered engineer — the HSE sets out the whole duty. Your existing tenants must get a copy of the record within 28 days of the check. A new tenant must get it before they occupy the property. And you must keep each record until two further checks have been carried out on that appliance or flue, which in practice means holding three years of records rather than the two years landlords often quote. Where an appliance or flue is taken out of the property, its last record is kept for two years from the date of that check.
Underneath those four is a fifth duty people forget, because it has no paperwork attached: the appliances and flues have to be kept in a safe condition, not just found safe once a year. The annual check is evidence of a duty, not the whole of it.
The rest of this is what the visit actually involves on Teesside rental stock, and the one confusion that costs landlords real money.
The document is a record, and that word matters
Everybody calls it a certificate. The regulations call it a record, and the difference is not pedantry. A certificate implies a pass. The record states what the engineer found on the day, including what they found wrong, and it is issued either way.
The other name you will see is CP12, from Corgi Proforma 12, the old numbered form. Corgi stopped being the registration body in 2009 and the document is now properly the Landlord Gas Safety Record. Letting agents, portals and half the trade still say CP12, so all three names are in circulation for the same piece of paper. If an agent asks for a CP12 and your engineer hands you an LGSR, nothing has gone wrong.
What has to be on it is set out in the regulations: the date, the address, your name and address, each appliance with its location and description, any safety defect identified, any remedial action taken, confirmation that the check meets the requirements of regulation 26(9), and the engineer's name, signature and registration number.
Once it exists, three things happen to it, and the HSE states all three. An existing tenant gets a copy within 28 days of the check being completed. A prospective tenant gets one before they move in, not at some point afterwards. And you keep the records for at least two years, which matters more than it sounds: the argument about whether last year's check happened is one you win with a file rather than a memory.
What the engineer does at each appliance
The core of the check is four examinations, taken from regulation 26(9) and applied to every appliance you provide.
| What is examined | What it answers |
|---|---|
| Effectiveness of the flue | Are the products of combustion going outside, and staying outside |
| Supply of combustion air | Is there enough ventilation for the appliance to burn properly |
| Operating pressure or heat input | Is the appliance running to its own specification, or has it drifted |
| Operation and safe functioning | Do the safety devices actually do what they exist to do |
Where examining pressure or heat input is not reasonably practicable, combustion performance is examined instead. Those four are a floor rather than a ceiling: the regulations say the check includes them but is not limited to them. Most records also carry a tightness test on the installation and a look at the emergency control valve and the protective bonding, because an engineer cannot sensibly sign off appliances while ignoring what feeds them.
The practical consequence for a landlord is that time on site scales with appliance count. A Coulby Newham semi with a combi and nothing else is one appliance. A Gresham or Linthorpe terrace with a boiler, a gas fire in the front room chimney breast and a gas cooker in the kitchen is three, and the flue on a live gas fire in a Victorian chimney is the slowest part of the visit.
Why a service is not included
This is the misunderstanding worth fixing before you book anything. The safety check answers whether the appliance is safe to use now. A service is condition work: stripping and cleaning where the manufacturer requires it, inspecting components, putting right things that are drifting before they fail.
The HSE treats them as separate duties. Its guidance says appliances should be serviced in line with the manufacturer's instructions, and annually where no instructions are available, and describes minimum effective maintenance as examining the physical condition and safe functioning of the appliances, the installation pipework, the ventilation and any flue for deterioration.
So a boiler can pass a safety check in October and break down in January without anything having gone wrong with the check. It was safe. Nobody asked it to be reliable. If you want both, ask for both when you book, and expect it to be priced as both. Our companion piece on what a boiler service covers goes through the service side properly.
What moves the price
Search for landlord gas safety certificate cost and you get a spread of numbers with no property attached to any of them. We will not add another one. What is worth knowing is which variables an honest quote is actually responding to.
| Driver | Why it moves the number |
|---|---|
| Number of gas appliances | The largest single factor. Each appliance is a separate examination |
| A live gas fire or back boiler | Older appliances and chimney flues take longer to test than a modern room-sealed combi |
| Occupied or void | A void gets done in one visit. A tenanted property may need evening access or a second attempt |
| Travel and clustering | Four properties on the same round is not four separate journeys |
| Remedial work found | Priced separately, after you have seen what it is |
| Whether a service is included | Two different jobs, two different amounts of time |
We quote in writing, there is no call-out fee on quoted work, and if remedial work is needed you get told what it is and what it costs before anyone starts it. We will not sign off appliances we have not seen, and we will not certify gas work somebody else carried out.
When an appliance is failed
Engineers work to the gas industry unsafe situations procedure, IGEM/G/11 — currently Edition 2, amended in July 2022, June 2024 and July 2025 — and it has two unsafe classifications rather than three. Immediately Dangerous means an installation that is an immediate danger to life or property if it is used or left connected. At Risk means one or more faults that constitute a potential danger. Both carry the same message to the customer, Danger Do Not Use, and both come with a warning notice.
The third label many landlords remember, Not to Current Standards, was taken out of the procedure in 2016, on the reasoning that a situation which is not unsafe should not dilute a safety warning. An engineer can still tell you an installation no longer meets today's standards, and a good one will, but that is advice rather than a formal classification and it does not belong on a warning notice.
A label is not attached in every case. Where turning the gas off would not actually reduce the risk, which happens with some faults on the supply side rather than the appliance, no label goes on, but the warning notice is still issued and it has to explain why. And an engineer cannot simply disconnect your appliance either way: permission is needed from the responsible person, and for an Immediately Dangerous situation where permission is refused, the engineer must report it to the gas emergency service provider. Nothing is done to your property behind your back, and nothing dangerous is quietly left.
If a tenant ever reports a smell of gas, treat it as an emergency and not a maintenance call. The official advice is to open doors and windows, turn the supply off at the meter control handle unless the meter is in a cellar, keep away from electrical switches and naked flames, and ring the National Gas Emergency Service free on 0800 111 999.
The other annual duty on a let is electrical, under the Electrical Safety Standards Regulations 2020 — a five-year cycle rather than a yearly one, explained here.
Getting it scheduled
Book it before the last one expires, not after. From 6 April 2018 you can have the check done in the two months before the deadline without losing the original deadline date, which is what makes a portfolio schedulable rather than scattered across twelve months.
Our Gas Safe engineers do landlord checks across the conurbation, and the record is emailed rather than left on a kitchen worktop for a tenant to lose. The gas and heating pages set out the wider work, with Middlesbrough and Redcar covered town by town.
Gas is only one of the two annual compliance jobs on a rented home. Read the EICR guide next, because the electrical duty runs on a five-year cycle rather than a yearly one and the two are easiest to manage together. Both are cheapest to do in a void, which is what the between-tenancy checklist is for. If you own several properties and have no schedule at all, send us the addresses and we will work backwards from your expiry dates.