What a gas safety certificate is
A Gas Safe registered engineer visits the property, checks every gas appliance and flue you provide, and writes up what they found. That write-up is the Landlord Gas Safety Record. Most people call it a CP12, after the old form number.
It records the appliances checked, the engineer's name and registration number, the date, the property address, and any safety defect found along with what was done about it. If an appliance is unsafe, the engineer will explain your options and, with your permission, disconnect it.
If you rent the property out, this is a legal duty rather than a good idea. It repeats every 12 months, and the record has to reach your tenant on time.
What the law asks of landlords
Four duties, and the last one catches people out.
A check every 12 months
Every gas appliance and flue you own and provide for your tenants must be safety checked every year by a Gas Safe registered engineer.
The record within 28 days
Your tenant gets a copy of the gas safety record within 28 days of the check. A new tenant gets theirs before they move in.
Keep records for two years
Hold on to each record for at least two years. If you use the early-check rule, keep it until two further checks have been done.
Servicing is a separate duty
A safety check is not a service. The regulations ask you to maintain appliances as well as check them, so don't assume one covers the other.
You can book up to two months early without losing your date
A rule introduced in 2018 lets you have the annual check done up to two months before it's due while keeping the original anniversary date. So if your certificate runs out in December, you can have it done in October and your next one is still due the following December. It's the simplest way to stop certificates drifting later each year, and it means you're never chasing an engineer in the last week.
Who needs one
- Private landlords, including anyone letting a single flat
- Housing associations and local authorities
- Hotels, B&Bs and hostels
- Colleges and boarding schools
- Anyone with a lodger paying rent
- Empty properties, before a new tenant moves in
If you live in your own home there's no legal duty, but an annual check is still worth having.
What's included
- Gas tightness test on the installation
- Every landlord-supplied appliance and flue checked
- Burner pressure and gas rate against the manufacturer's data
- Flue flow and spillage testing
- Ventilation checked against current standards
- Safety devices tested
- The Landlord Gas Safety Record, issued the same day
A check and a service are not the same thing
This is the most common misunderstanding in landlord gas safety. The safety check answers one question: is this appliance safe to use today? A service is the manufacturer's maintenance work — cleaning, replacing worn parts, checking the appliance is running as designed.
The regulations ask landlords to do both: keep appliances maintained, and have them safety checked every year. The HSE is explicit that you shouldn't assume a service covers the safety check, or that a safety check counts as maintenance.
In practice, having both done in one visit is cheaper and means one appointment for your tenant. Ask us for both when you book, or look at boiler servicing.
Gas Safe registered engineers
Hem isn't Gas Safe registered itself; gas work is carried out by Gas Safe registered engineers, and you can check any registration before they start.
Inside the M25 and just outside
One team for the whole portfolio, with certificates tracked in one place.
From £80, record the same day
Fixed price before we book, and you get the record digitally on the day, so the 28-day clock is never a problem.
Gas safety questions landlords ask
How often does a rented property need a gas safety check?
Every 12 months, on each gas appliance and flue you provide. The check has to be done by a Gas Safe registered engineer, and you need a new record each year.
How much does a gas safety certificate cost in London?
From £80 for a typical flat with one boiler. Properties with more gas appliances cost a little more, so we confirm a fixed price before we book. Members get 5% to 20% off certificates and at least one free certificate a year. Having the annual service done in the same visit works out cheaper than two appointments.
Can I get the check done early without losing my renewal date?
Yes. Since 2018 you can have the check done up to two months before it's due and keep the original anniversary date, so booking early doesn't shorten your next certificate.
What's the difference between a gas safety check and a boiler service?
A safety check confirms an appliance is safe to use right now. A service is the manufacturer's maintenance work that keeps it running properly. The regulations ask landlords to do both, and the HSE says not to assume either one covers the other. We'll usually do them in the same visit.
Who has to get one?
Private landlords, housing associations, councils, hotels, B&Bs, hostels, colleges and boarding schools. If you have a lodger paying rent, it applies to you too. Owner-occupiers don't need one by law, though an annual check is still sensible.
When does the tenant get a copy?
Within 28 days of the check for an existing tenant, and before they move in for a new one. Keep each record for at least two years.
What if my tenant won't let the engineer in?
Keep trying and write it all down. The HSE expects at least three documented attempts, including a written notice explaining that the check is a legal safety requirement. We can supply appointment options in writing to help build that record.
What happens if I don't have one?
Gas safety is enforced by the HSE, and breaches can lead to a substantial fine or a custodial sentence. It also affects your position on possession proceedings and your insurance.
Are your engineers Gas Safe registered?
Yes. Hem itself isn't Gas Safe registered — gas work is carried out by Gas Safe registered engineers we work with. You can check any engineer's registration on the Gas Safe Register before they start.
Bundle it with the rest
Most landlords need an EICR every five years alongside the annual gas check, and often PAT testing as well. A membership takes 5% to 20% off certificates, includes at least one free certificate a year, and brings the hourly rate down to £75–£80 for any work that follows.
The duties on this page come from HSE guidance for landlords under the Gas Safety (Installation and Use) Regulations 1998, as amended in 2018, and were last checked on 12 September 2026. It's a summary written to be useful, not legal advice. Landlords remain responsible for confirming their own obligations.