What Is a Gas Safety Certificate and How Do I Get One?

If your rental property has any gas appliance, pipework or flue, you have a legal duty to keep it safe and to prove it. The document that proves it is the Gas Safety Record, which many landlords still call a gas safety certificate or a CP12. It is one of the most important and most frequently misunderstood parts of letting a home in London, so it is worth setting out clearly what it is, who issues it, and how you stay on the right side of the rules.

What is a Gas Safety Certificate?

A Gas Safety Record is a written confirmation that the gas appliances and installations in your property have been checked and are safe to use. By law a landlord must arrange an annual gas safety check carried out by a Gas Safe registered engineer, and must give a copy of that record to the tenant. The older industry shorthand 'CP12' refers to the form the engineer completes, but the legal point is the same: every year, every property with gas, a qualified check.

The record covers the things a tenant cannot easily judge for themselves, such as whether an appliance is burning correctly, whether flues and chimneys are carrying fumes safely away, and whether gas pressure and ventilation are within safe limits. It is about protecting people from carbon monoxide and gas leaks, which is why the rules are strict and the timing is not flexible.

Who can issue one, and what does it cover?

Only an engineer on the Gas Safe Register can carry out the check and issue the record. Anyone can claim to know boilers, but the Gas Safe Register is the official list, and you can ask to see the engineer's identity card before any work begins. It is sensible to keep a note of the engineer's registration number alongside your copy of the record.

During the visit the engineer will inspect each gas appliance the landlord is responsible for, the associated pipework and the flues. They will check that appliances are working safely, that there is adequate ventilation, and that safety devices operate as they should. If something is unsafe, the engineer should make it safe or advise that an appliance is taken out of use until it is repaired. A boiler service is a separate thing from a safety check, although many landlords arrange both on the same visit for convenience.

How often do you need one, and when does the clock start?

The check is annual. A new record is required within twelve months of the last one, and you do not have to wait for the certificate to expire before renewing. In practice it is good discipline to book the check a little early each year so a missed appointment or a busy engineer never tips you into a lapse. You must give the current record to existing tenants, and you must give it to any new tenant before they move in.

Keeping certificates current is one of the quieter parts of being a landlord, but it sits alongside several others. We set the full picture out in our overview of a landlord's legal obligations in London, which is a useful companion if you are letting for the first time or taking on a new property.

How a Gas Safety Certificate fits with your other compliance documents

Gas safety rarely travels alone. Most London lettings also need an Energy Performance Certificate before the property can be marketed, and an electrical safety report. The EICR, which we cover in our guide on when an EICR is needed and how long it lasts, is required at least every five years, while the gas check is yearly, so the two run on different cycles and are easy to confuse. A simple diary or spreadsheet that lists each document, its issue date and its renewal date will save a great deal of last-minute scrambling.

Alongside these certificates, the law requires a smoke alarm on every storey of the property and a carbon monoxide alarm in any room containing a fixed combustion appliance, such as a gas boiler or a gas fire. These alarms are inexpensive and directly relevant to gas safety, so it is worth checking them at the same time as you arrange the annual gas check.

Common mistakes landlords make

• Letting the renewal date drift because the old certificate had not yet 'run out'
• Forgetting to hand the record to a new tenant before move-in, or to existing tenants after each check
• Assuming an appliance the tenant owns is the landlord's responsibility, or vice versa, when it is not
• Using an engineer who is not on the Gas Safe Register

Most of these come down to record-keeping rather than cost, and they are entirely avoidable with a little forward planning.

Where this sits in the wider letting picture

Gas safety is one piece of a larger compliance and tenancy framework that has changed considerably in recent years. If you want to see how it sits within everything else, from referencing to deposits to the new periodic tenancy rules, our complete guide to letting a property in London walks through the journey end to end. The rules introduced under the Renters' Rights Act have also reshaped how tenancies run, and our summary of what the Renters' Rights Act 2025 means for London landlords is a helpful read for context.

This article is general information rather than legal or technical advice, and gas regulations carry real safety and legal weight, so a Gas Safe registered engineer should always carry out the work and any specific questions are best put to a qualified professional.

If keeping track of annual gas checks, certificates and renewal dates feels like one job too many, this is exactly the kind of routine we handle for the landlords we look after. We are always happy to talk it through, with no pressure, so you can let your property knowing the compliance side is quietly taken care of.