Northampton · West Northamptonshire
CP12 vs Boiler Service: The Difference That Can Fine You
The two most confused documents in British landlording. They overlap in timing, share an engineer, and do completely different jobs.
Side by side
| CP12 (gas safety check) | Boiler service | |
|---|---|---|
| Legal basis | Mandatory — Reg 36, Gas Safety Regs 1998 | Contractual — warranty condition |
| Question answered | "Is it safe today?" | "Is it maintained for the year?" |
| Includes | Flue flow, pressure, safety devices, visual | Clean heat exchanger, burner service, analyser readings vs manufacturer limits, seals |
| Output | Landlord Gas Safety Record (CP12) | Service record in Benchmark logbook |
| Frequency | Every 12 months | Every 12 months |
| Without it | Criminal offence | Void warranty, higher breakdown risk |
The landlord failure modes
1. Service instead of CP12. A pristine service record does not satisfy Regulation 36 if the statutory check wasn't done and recorded. HSE does not accept "it was serviced" as a defence. 2. CP12 instead of service. Compliance is fine — but warranty is void, efficiency degrades, and the repair bills arrive in January. 3. One document for two properties. Records are property-specific.
The efficient answer
Book a combined visit: service first, CP12 second, one call-out fee. The engineer's paperwork then covers both the legal duty and the manufacturer logbook. Most Northampton engineers price the bundle at £110–£180 (indicative 2026) — cheaper than two visits.