Landlord gas safety certificate (CP12) explained

If you rent out a home with gas, you need a Gas Safe engineer to check every gas appliance and flue you provide, every year, and give your tenants the record. This guide covers the rules from HSE and Gas Safe Register, what the record must include, what it costs, and how engineers issue it, checked on 12 October 2026.

What are the landlord gas safety rules?

The rules come from the Gas Safety (Installation and Use) Regulations 1998, which apply in England, Scotland and Wales. Here they are in plain English, taken from HSE's landlord guidance.

How often

Every 12 months, for each gas appliance and flue you provide. New appliances must be checked within 12 months of installation.

Who does it

A Gas Safe registered engineer who is qualified for that type of appliance.

Early checks

Allowed up to 2 months before the due date, without losing the original deadline.

Tenant copies

Existing tenants within 28 days of the check. New tenants before they move in.

Keeping records

At least 2 years, or until two further checks are done if you use the early check option.

Digital records

Allowed if they can be printed, are secure, and identify the engineer.

Penalty

HSE says a breach "could result in a substantial fine and/or a custodial sentence".

Gas Safe Register adds two practical points. For lets under 28 days (such as holiday lets), you can display a copy in the property instead. And you must keep the pipework, appliances, chimneys and flues safe between checks, servicing them as the manufacturer recommends, or every year if there is no guidance.

Who do the rules apply to?

HSE says the landlord duties apply to anyone who rents out a property they own on a lease of less than 7 years, or under a licence. That covers far more than a standard buy-to-let flat:

• Private rented homes and houses in multiple occupation (HMOs)
• Social housing
• Bedsits, rooms in a B&B or hotel
• Rented holiday homes, chalets and caravans

What is covered, and what is not

The duty covers gas appliances, fittings, flues and pipework that the landlord owns and provides for tenants, including shared items such as a communal boiler. If a tenant brings their own gas cooker or fire, the landlord is not responsible for that appliance. But the landlord still has duties for the pipework feeding it, and HSE suggests checking any flue connected to it as part of the landlord's check.

Letting agents

If your management contract makes the agent responsible for gas safety, the agent takes on the same legal duties. Make that split clear in writing, because "I thought the agent was doing it" is not a defence.

Scotland, Wales and Northern Ireland

The same 1998 regulations apply in Scotland and Wales. Carbon monoxide alarm rules differ: Gas Safe Register notes that in Scotland a CO detector is needed wherever there is a fixed combustion appliance (except one used only for cooking). Northern Ireland has its own law, the Gas Safety (Installation and Use) Regulations (Northern Ireland) 2004. HSENI's guidance sets the same core duties: a check every year, records kept for 2 years, and a copy to tenants within 28 days. In December 2025 HSENI consulted on adding the same early check flexibility that Great Britain already has, so check HSENI for whether that has come into force.

How do you get a landlord gas safety certificate, step by step?

1. List every gas appliance and flue you provide. Boiler, hob, oven, gas fire, water heater and any flue. Note which ones belong to the tenant.
2. Book a Gas Safe registered engineer. Check them on the Gas Safe Register and make sure they are qualified for each appliance type. Booking 10 to 12 months after the last check keeps your due date the same.
3. Arrange access in writing. Give the tenant notice. If they refuse, do not force entry. Write to them, leave a notice and log every attempt. HSE inspectors look for at least three.
4. The engineer checks each appliance and flue. The record must confirm the checks required by regulation 26(9) were done. Gas Safe Register also suggests asking for a tightness test of the whole system and a visual check of the pipework.
5. The engineer issues the record straight away. HSE says it should not be held back because a fault was found or a repair is pending. Any defect and the action taken go on the record.
6. Fix any defects. An appliance classed as dangerous may be disconnected until it is repaired. Get the record updated after the follow-up work.
7. Give tenants a copy. Existing tenants within 28 days. New tenants before they move in. Short lets: display it.
8. File it and set a reminder. Keep it for at least 2 years. Put the next due date in your diary, or let your engineer's software remind you.

What must the record include?

HSE lists seven items. If any are missing, the record is not complete.

How much does a gas safety certificate cost, and when is it due?

There is no fixed price. Two current cost guides give similar ranges:

Bundling the check with the annual boiler service usually costs less than two separate visits, and it ticks off the maintenance duty at the same time.

Deadlines that catch people out

• The 12-month clock. Each appliance is due 12 months after its last check.
• The 2-month early window. Check up to 2 months early and the due date stays the same. Any earlier and the clock resets to the new check date.
• 28 days to the tenant. This counts from the date the check was completed.
• Before move-in. A new tenant must have a copy before they move in, not on the day they sign.

Worked example: dates and costs for a small portfolio

A landlord has two flats outside London. Flat A has a boiler and a gas hob. Flat B has a boiler only. Both were last checked on 15 May 2026.

The landlord books both checks for 20 March 2027, which is inside the 2-month window. The next due date stays at 15 May 2028, not 20 March 2028. The tenants must have their copies by 17 April 2027 (28 days after the check). Budget: £120 to £170 for CP12s only, or £180 to £300 if both boilers are serviced on the same visit.

Now the engineer's side. If a gas engineer does five CP12s in a day at £80 each, that is £400 of work. The paperwork is where time leaks: writing up records, emailing landlords and agents, and remembering who is due next year. That is the job certificate apps do.

What are the most common mistakes?

1. Checking too early. A check 3 months early resets the due date, so you lose a month every year.
2. Forgetting the flue on a tenant's own appliance. The appliance is theirs, but HSE suggests checking the connected flue in your check.
3. Sending the record late. 28 days runs from the check, not from when the landlord got round to forwarding it.
4. Holding back the record because of a defect. HSE says issue it anyway, with the defect and the action recorded.
5. No evidence of access attempts. If the tenant refuses, keep letters, emails and notices. One text message is not enough.
6. Treating the CP12 as a service. The safety check is not the same as maintenance. You still need to keep appliances maintained.
7. Losing old records. Keep at least 2 years. Digital storage is fine if it is secure and printable.

What software helps gas engineers issue CP12s?

For engineers, a CP12 app replaces the carbon-copy pad. You fill in the record on a phone or tablet, the customer signs on screen, and the PDF goes to the landlord and agent before you leave. The better apps also remind the landlord when the next check is due, which turns compliance into repeat work.

Tradify's gas forms include the Landlord/Homeowner Gas Safety Record, warning notice, service and maintenance record, and commissioning records, on the Pro plan and above. It is our pick for small gas and heating teams that want quotes, scheduling and invoicing in the same app as their CP12s.

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For a full side-by-side of every app, see our comparison of gas certificate apps. If certificates are all you need, our Gas Engineer Software review covers the cheapest dedicated option. And if you run a growing heating firm, our guide to software for heating engineers compares the job management tools as well.