Boiler Service Cost Calculator
An annual service is usually a warranty condition, not an optional extra. This prices the service, the landlord certificate and the two together.
Open the calculator →Price a boiler service in 30 seconds
4 steps. Covers boiler type, whether you need a CP12 certificate, extra gas appliances and region.
How this calculator works
A service and a CP12 are different things and it is worth being clear which you are buying. A service cleans, tests and maintains the appliance. A CP12 is a landlord gas safety record — it certifies that appliances are safe on the day, and it neither cleans nor maintains anything. Landlords need the CP12 every 12 months by law; the service is what actually keeps the boiler working and the warranty intact.
Booking both in one visit is the cheapest route by some margin, which is why the calculator prices the combination rather than adding two separate call-outs. A CP12 must cover every gas appliance in the property, so the extra-appliance question is not optional for landlords. Homeowners who are not landlords do not need a CP12 at all, so if you are being sold one on an owner-occupied house it is worth asking why: what you almost certainly want is the service that keeps the warranty valid, not the landlord certificate that does nothing to maintain the boiler. A proper service is more than a visual once-over: the engineer should run a flue-gas analysis, check the combustion seals and the gas pressure, and log the readings, so ask to see them rather than accept a ticked box. Miss a year and most manufacturers treat the warranty as void, which is the expensive way to save a service fee. If the checks turn up a wider heating fault, our central heating cost calculator prices a system upgrade, and if the boiler is getting on, the best boiler brands guide is worth a look before you spend on an old unit.
Boiler service and CP12 costs (2026)
| Service | Typical 2026 cost | Notes |
|---|---|---|
| One-off annual service (combi) | £70–£120 | The standard job |
| One-off service (system / regular) | £80–£130 | Cylinder and extra controls to check |
| Landlord gas safety check (CP12) | £60–£90 | Certificate only, no maintenance |
| CP12 — each additional appliance | +£10–£30 | Hob, fire or heater |
| Combined service + CP12 | £100–£150 | Cheapest route for landlords |
| Manufacturer / warranty-brand service | £99–£180 | Where the warranty demands it |
| Boiler cover plan | £10–£25 / month | Service usually included |
Figures match our boiler service cost guide. Check your warranty terms before booking — some brands require their own engineer, and a missed annual service is the most common reason a warranty claim is refused.
Boiler service calculator FAQs
For warranty purposes, almost always yes — most manufacturers require a documented annual service, and a missed one is the most common reason a claim is refused. It also catches the cheap faults early: a £200 pump replaced on a service visit is better than a failure in January. Keep the paperwork as well as booking the visit: manufacturers ask for a dated service record when a claim is made, so a service that was done but never logged can be almost as much of a problem as one that was skipped.
A service cleans, tests and maintains the boiler. A CP12 is a landlord gas safety record confirming appliances are safe on the day of inspection — it is a legal duty for rented property every 12 months, and it does not maintain anything. Landlords generally want both, done in one visit.
It depends on the boiler. On a unit under about eight years old with a live warranty, usually not — you are insuring against a risk the warranty already carries. On an older out-of-warranty boiler, £10–£25 a month can be reasonable, but read what is excluded, particularly pre-existing faults and any parts cap. Check the annual claim limit and whether the boiler itself is covered or only labour, because a plan that excludes the heat exchanger on an older boiler leaves out the one repair expensive enough to make cover worthwhile in the first place.
No, and this is a common and expensive misunderstanding. A CP12 confirms safety on the day. If your warranty requires an annual service, a CP12 alone will not satisfy it — you need the service documented as well.
Related cost guides
- Boiler service cost guide — services, CP12s and cover plans
- Boiler repair calculator — price a specific fault
- Boiler replacement calculator — when a service is not enough
- Building regs for boilers — notification and certificates
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