What Does a CP12 Actually Include? (Landlord Gas Safety Certificate Explained — 2025 Guide)

Every UK landlord must provide a valid CP12 Gas Safety Certificate every 12 months. Learn exactly what a CP12 covers, what it doesn't include, legal requirements, costs, and how to stay compliant.

Introduction

Every UK landlord must provide tenants with a valid CP12 Gas Safety Certificate every 12 months. But many landlords — and even some agents — aren't fully clear on what a CP12 actually covers, what it doesn't include, and what engineers legally must check.

This guide breaks it down clearly so you stay compliant and avoid penalties of up to £6,000 per property, invalid insurance, or legal disputes with tenants.

1. What Is a CP12?

A CP12, also known as a Landlord Gas Safety Certificate, is a legally required inspection carried out by a Gas Safe registered engineer.

It ensures that all gas appliances and pipework in a rental property are safe and operating correctly.

A CP12 is not optional for landlords in England, Scotland, or Wales.

2. What Does a CP12 Inspection Include?

A proper CP12 must include all of the following checks:

✔ 1. Gas Boiler Safety Check

The engineer inspects:

• Burner operation
• Gas pressure
• Flue flow / ventilation
• Heat exchanger
• Seals & safety devices
• Combustion analysis
• Presence of carbon monoxide risks

✔ 2. Gas Meter & Pipework Check

• Visual inspection for corrosion or leaks
• Tightness test
• Regulator checks
• Emergency control valve test

✔ 3. Up to Three Gas Appliances

(cooker, gas hob, gas fire, water heater)

Checks include:

• Gas supply
• Burner flame quality
• Ventilation
• Stability/security
• CO readings
• Safety shutoff valves

✔ 4. Flue & Chimney Examination

• Blockages
• Adequate ventilation
• Safe removal of fumes
• CO risk assessment

✔ 5. Carbon Monoxide Checks

Engineers test for:

• CO spillage
• CO alarm presence (if required)
• Proper combustion

✔ 6. Compliance Review

Your engineer must confirm the property meets all current safety regulations.

✔ 7. Digital or Paper Certificate with Findings

You (and your tenant) receive the CP12 certificate showing:

• Engineer's details (Gas Safe number)
• Appliance list
• Pass/fail status
• Any defects
• Required remedial works

3. What a CP12 Does NOT Include

A CP12 is a safety check, not a servicing appointment.

It does not include:

• ❌ Full boiler service
• ❌ Replacement of parts
• ❌ Repair of faults
• ❌ Performance optimisation
• ❌ Radiator bleeding
• ❌ System flushing
• ❌ CO alarm installation
• ❌ Checking non-gas appliances
• ❌ Checking more than 3 gas appliances

For many landlords, this is a surprise — which is why most choose to include an annual boiler service alongside the CP12.

View Landlord Home Emergency Cover with CP12 included

4. How Long Does a CP12 Take?

• Standard check: 20–40 minutes
• Properties with 3 appliances: 40–60 minutes
• Older boilers: may take longer
• Failing appliances: longer inspection

5. How Much Should a CP12 Cost in 2025?

Average UK pricing:

Many landlords now bundle CP12 into emergency cover plans because standalone certificates add up.

6. Legal Deadlines Landlords MUST Follow

Legal requirements:

• Must be completed every 12 months
• Tenants must receive a copy within 28 days
• New tenants must receive it before moving in
• You must keep records for 2 years

Failing to comply is a criminal offence.

7. What Happens If a CP12 Fails?

A failure doesn't always mean danger — it means something must be corrected.

If your CP12 fails:

• Landlord must fix the issue
• Work must be done by a Gas Safe engineer
• A new CP12 is issued after corrective work
• Tenant must receive updated certificate

Common failure reasons:

• Faulty flues
• Incorrect gas pressure
• CO spillage
• Broken safety devices
• Old gas fires
• Blocked ventilation

8. The Difference Between CP12 and a Boiler Service

Most landlords purchase both to keep boilers reliable and tenants safe.

9. Why Landlords Choose Emergency Cover With CP12 Included

Emergency cover plans with CP12 included give landlords:

• ✔ One predictable monthly cost
• ✔ CP12 every year
• ✔ EICR every 5 years
• ✔ Annual boiler service
• ✔ Priority repairs for tenants
• ✔ No call-out fees
• ✔ 24/7 support
• ✔ Full compliance in one place

This significantly reduces legal and operational stress.

See Landlord Plans