CP12 Explained: Landlord Gas Safety Rules, and the 2-Month Rule Worth Knowing

If you do gas work on rented property, you'll know the rhythm. A landlord rings up because their certificate expired last week, or a letting agent wants six properties done before Friday, or a tenant's been chasing paperwork nobody sent them.

Most of that is avoidable, and one rule in particular — the two-month rule — exists specifically to make it avoidable. A lot of people either don't know about it or don't trust it.

Here's what the regulations actually say.

First, "CP12" isn't really a thing any more

The document everyone calls a CP12 is properly a Landlord Gas Safety Record. CP12 was a CORGI form number, and CORGI stopped being the gas registration body back in 2009. The name stuck the way names do.

So when a landlord asks for a CP12, they mean the Landlord Gas Safety Record. Worth knowing if only because it tells you roughly how long they've been letting property.

The duties, in plain terms

These come from the Gas Safety (Installation and Use) Regulations 1998, and they apply in England, Wales and Scotland. Northern Ireland has its own separate regime, so check locally if you work there.

Only a Gas Safe registered engineer can do the check. And the landlord is expected to check the ID card — not just that the engineer is registered, but that they hold the specific qualifications for the appliance in question. Being on the register isn't a blanket licence for every appliance in the house.

Annually. Within 12 months of an appliance being installed, then every 12 months after.

Existing tenants get a copy within 28 days of the check being completed.

New tenants get a copy before they move in. Not on the day, not in the welcome pack a fortnight later. Before.

Records are kept for 2 years.

Electronic records are fine, provided they can be reproduced as hard copy, they're held securely against loss, and each one uniquely identifies the engineer who did the work — a signature or an ID number.

The two-month rule

This is the useful one.

A check carried out up to 2 months before the date it's due still keeps the original anniversary date.

So a certificate due 1 March can be done any time from 1 January onwards, and next year's is still due 1 March. You don't lose two months. The deadline doesn't creep forward each year.

What that means practically is that every gas safety check in your book has a two-month window, not a deadline. You can pull work forward into a quiet January instead of cramming it into the week it expires. You can batch a letting agent's portfolio into one run rather than six separate visits across six months. And a landlord who's away, or a tenant who works shifts, has sixty days of flexibility rather than none.

The reason this rule gets wasted is almost always record-keeping. If you don't know which certificates are coming up, you can't pull anything forward — you only find out when someone rings you because it's already expired.

What's actually covered

The landlord's duty covers the gas appliances, fittings and flues provided for the tenant's use, including those in communal areas.

Tenant-owned appliances are the bit people get wrong. If the tenant brought their own gas cooker, the landlord is still responsible for the installation and pipework serving it — just not for the appliance itself. That distinction matters when you're writing up what you did and didn't inspect.

And one that comes up in arguments: a landlord cannot pass these duties to the tenant through the tenancy agreement. A clause saying the tenant is responsible for arranging the gas check doesn't work. The duty stays with the landlord regardless of what's been signed.

Why this is a business problem, not a compliance one

For a heating business, annual certificates are the closest thing you get to recurring revenue. Same property, same time every year, entirely predictable.

Except it only works if someone is tracking the dates. The common failure isn't losing customers to a competitor — it's that nobody remembered the certificate was due, the landlord got a reminder from somewhere else first, and that job quietly left the book. Nobody notices a job that doesn't get booked.

If you're keeping renewal dates in a diary or a spreadsheet, you're relying on remembering to look at it. That works until you're busy, which is exactly when it matters.

This is the problem FlowSync was built for: it tracks when each customer's gas safety check or boiler service is due, and chases the rebooking before the date rather than after it — which is also when the two-month rule is still available to you.

One caveat

This is a summary of how the rules work, not legal advice, and it doesn't cover every situation — HMOs, some commercial premises, and Northern Ireland all have wrinkles this doesn't address. The HSE's own landlord guidance is the authority, and Gas Safe Register is the place to confirm anything about registration and qualifications. If either of them says something different from this page, believe them.

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FlowSync keeps track of when every customer's next service or certificate is due, sends the reminder, and chases the booking. Try it free for 14 days — no card needed. Or work out what a job actually earns you with the free job profit calculator.