Annual boiler service reminders: recurring revenue you don't have to chase

Book next year's boiler service before you leave this one, put the date in your diary, and send the customer a short reminder a few weeks ahead. The rebook then stops depending on anyone's memory. In Radar's 2022 survey of 13,961 people in the Netherlands with a boiler maintenance contract, 79% said the company itself gets in touch when the service is due.

My argument here is that the customers you serviced once, with no contract and no date booked, are where the yearly rebook leaks.

How much does a skipped annual service cost you?

About £79 a visit in the UK, going by the UK consumer organisation Which?, which wrote in October 2025 that a boiler service costs "around £79 on average, though some can be up to £120 depending on where you are".

A MoneySuperMarket survey of 2,000 UK adults, run in December 2024, found a fifth of households (22%) are not getting an annual boiler service. Among them, 31.4% said cost was the main reason. That is the only reason the article puts a figure on, so it cannot tell you how many people simply never got round to ringing.

Now run it on your own book. Say you serviced 300 boilers last year and a fifth of those customers don't book again this year, the same share of households MoneySuperMarket found without a yearly service: that is 60 services. At Which?'s £79 average, 60 × £79 is £4,740 you will not invoice this year.

In the Netherlands the visit is also sold as a maintenance contract. Radar found 45% of its contract holders had theirs with a local installer, and among those paying by the year, the most common price was €60 to €110.

Who should make the first move, you or the customer?

You. In Radar's survey, 79% said the company contacts them when the service is due, 9% have to ring the company themselves, and for 12% it is sometimes one, sometimes the other.

Leaving it to the customer is where the friction shows. Of the people who have to ring to arrange the visit, Radar says 1 in 10 needs several calls or emails to get an appointment booked, and for another 2% it does not happen at all. Those are customers who already pay for the service and still struggle to get it on the calendar.

A one-off customer has even less pulling them back, because there is no contract and no date in either diary. If they do remember, the call may come while you're under somebody else's sink. Call-tracking firm Invoca's platform data shows that less than 3% of callers who get pushed to voicemail leave a message, and we looked at where the rest go in a separate post.

A service you booked before you left is an appointment. A service you are waiting for the customer to remember is a hope.

When should the reminder go out?

A few weeks before the date you booked, and the date itself belongs in your quiet months if the customer will take it. Boiler Guide analysed ten years of boiler repair enquiries from UK households, received between 2009 and 2019, and found July the quietest month at 3.8% of enquiries, against 15.56% in January. It says demand is always lower between March and October.

Which? adds the customer's side of the calendar: data by British Gas shows most boiler owners turn their heating on by the end of October, and putting the service off until December means a greater risk of an emergency breakdown. A service you book into July fills a slow week. The same customer ringing in January lands in the month Boiler Guide found busiest, alongside the cold-snap breakdown calls.

Check the interval while you're at it. In Radar's survey, 57% had a contract that checks the boiler once a year and 39% one that checks it every two years, so set the reminder to the interval the customer is actually on.

Is a boiler service reminder email marketing?

Sometimes. In the UK, a reminder about a visit that is already booked is a service message, while one that encourages the customer to book is likely to be marketing. The Information Commissioner's Office (ICO), the UK's data protection regulator, lists messages that "confirm or remind them about appointments" among service messages. It also says a message that "actively promotes or encourages people to make use of a particular service" is likely to be direct marketing, and that a service message with a marketing element in it counts as marketing.

So "your boiler service is booked for next Tuesday morning" is a reminder about an appointment. "It's been a year, book your service" is likely marketing, and under the UK rules unsolicited marketing email to an individual needs their consent or the soft opt-in. The ICO says the soft opt-in applies only where all of these are met:

• you obtained the recipient's contact details yourself;
• you did so while selling or negotiating to sell a product or service;
• you are only marketing your similar products and services;
• you gave them a chance to refuse or opt out when you collected the details;
• you give them a chance to opt out in every message after that.

If nobody was offered an opt-out when you took their email on the job, the soft opt-in does not cover a "book your service" email, and booking the date before you leave is the cleaner route.

In the Netherlands, the ACM (Autoriteit Consument & Markt) says on its page on avoiding spam that you may send existing customers unsolicited messages about products or services connected to their earlier purchases, as long as they can unsubscribe and you are clearly the sender, and that every message carries the unsubscribe option. That page is a summary. The law behind it, article 11.7(4) of the Telecommunicatiewet, covers electronic contact details you obtained from your customers when selling them a product or service, used for your own similar products or services, provided you clearly and explicitly gave them a free and easy chance to object when the details were collected, and in every message after that if they did not object then - and you must be able to show the details came from your customers that way. Among the conditions, then: send a reminder that asks them to book under your own business name, with an unsubscribe line and a valid postal address or number where they can ask you to stop, and only to customers who were given that chance when you took their email and did not object. Outside the UK and the Netherlands, check your own regulator's guidance before you send.

What should the reminder actually say?

Two or three sentences, one message for each case.

• The visit is booked: "Hi Sam, a reminder that your boiler service is booked for [date], between [time] and [time]. We set the date when we were last out. If it no longer suits, reply to this email or ring us and we'll move it."
• No date yet: "Hi Sam, we serviced your boiler last [month] and it's due again. You can pick a time here: [link]. If you'd rather not get these reminders, unsubscribe below."

Keep the booked one plain. A line about new boilers or a spring offer is the marketing element that, on the ICO's reading, makes the whole message marketing.

If you want a reason that is the customer's own rather than yours, Which? gives one: not keeping up with annual servicing can invalidate any warranty on the boiler. Send one reminder. If it gets no answer, a single follow-up a few weeks later is plenty, and after that the customer has told you something.

Where does SwiftGuard fit?

SwiftGuard doesn't send the reminder. It answers the call when the customer rings to book.

SwiftGuard answers around the clock and takes the caller's name, address and problem. Once you connect your Google Calendar, it offers only times you are free, and the job it agrees on lands in your calendar before the caller has hung up. Anything it can't handle, it says so honestly, takes a message and flags the call for you to ring back.

Start with last year's list

Count the boilers you serviced in the past twelve months. Then count how many of those customers already have a date in your diary for the next one. The difference, times your service price, is the recurring revenue currently waiting on your customers' memory.

Book the gap into next summer. And if the calls that would fill it are the ones you keep missing, the plans are here.