The landlord gas safety certificate, explained properly

What it actually is

Everyone calls it a CP12. That was a CORGI form number, and CORGI stopped being the gas registration body in 2009 — but the name stuck. Officially it is the Landlord Gas Safety Record: the document a Gas Safe registered engineer issues after checking every gas appliance and flue in a rented property.

It comes from the Gas Safety (Installation and Use) Regulations 1998, which put three duties on anyone letting a property with gas in it.

The three duties

1. An annual safety check. Every gas appliance and every flue, at least every 12 months, by a Gas Safe registered engineer.
2. A record, given to tenants. Within 28 days of the check for existing tenants, or at the start of the tenancy for new ones. Keep copies for two years.
3. Maintenance. Pipework, appliances and flues kept in a safe condition throughout the tenancy — not only on inspection day.

The 12-month rule, and the bit people miss

The check is annual. What catches landlords out is that having it done early used to reset the clock, so each year the renewal date crept forward and you effectively lost days off every cycle.

Since 2018 you can have the check carried out in the two months before the expiry date and keep the original anniversary date. So if your certificate expires on 1 December, a check any time from 1 October still renews to 1 December the following year. There is no reason to leave it to the last week.

What happens during the inspection

• Each appliance is checked for safe operation, with its gas pressure and burner performance tested against the manufacturer's figures.
• Flues and chimneys are checked to confirm combustion products are clearing properly — the check that matters most for carbon monoxide.
• Ventilation is checked, including whether anything has been boxed in or blocked since last year.
• The gas installation is tested for tightness from the meter onwards.
• Safety devices such as flame failure protection are proved to work.

Most properties take under an hour. The record lists every appliance, what was found, and whether it passed.

If something fails

Faults are classified by how dangerous they are, and you will be told exactly what was found. With your permission an immediately dangerous appliance will be disconnected and labelled — an engineer cannot simply leave it running and write it up. Once the fault is repaired and it passes, the record is issued.

What it costs you to skip

• Prosecution and fines. Enforcement is real, and the penalties are not trivial.
• Insurance. Landlord policies generally will not respond to a gas-related claim without a valid record.
• Section 21. In England, failing to give the tenant a valid gas safety record blocks a no-fault possession notice. Landlords discover this at the worst possible moment.

If the tenant will not let you in

You are expected to take all reasonable steps, and to be able to show it. Keep a written record of every attempt: letters, texts, the dates of missed appointments. That paper trail is your defence. In practice, offering evening and weekend slots removes most of the problem — it is usually a working-hours issue rather than obstruction.

Two things that are not the same as a CP12

A service is not a safety check. The check confirms an appliance is safe on the day. A service cleans, tests and adjusts the boiler so it keeps working. Many landlords have both done in one visit, which is usually cheaper than two.

An electrical certificate is separate. The EICR is a different inspection by a different trade on a different cycle. Do not assume one covers the other.

This article is general guidance, not legal advice. For the definitive position see the Health and Safety Executive's landlord guidance and the Gas Safe Register.