In autumn, the phone rings more often: the heating needs to work before the first frost, the ventilation system has not been cleaned for years, and the inspection of the electrical installations at the law firm next door still has no date. Many businesses handle these requests one by one, often just when they are busiest anyway. Maintenance contracts reverse this pattern. They turn recurring work into predictable appointments and predictable revenue, and they let a business fill quieter weeks deliberately instead of waiting for calls.
This guide is for owners and office teams in businesses with roughly 1 to 50 employees. It shows which contract models work well, how to record intervals and deadlines properly, how appointments reach the calendar in good time, and what matters for invoicing and customer loyalty.
Why recurring maintenance pays off for trade businesses
A maintenance contract is more than an appointment reminder. It defines which system is serviced at what interval, with what scope of work and at what price. This gives the business three advantages: workload can be planned earlier, income becomes more predictable, and contact with the customer continues between larger jobs. If you service a system regularly, you know its condition, spot wear early and are the first point of contact when a modernisation is due.
For customers, the benefit is just as tangible: they do not have to keep track of deadlines themselves, they have a fixed point of contact and they can budget for costs more easily. For heating, ventilation, refrigeration and air conditioning, electrical installations or lifts, regular servicing is sensible or even required – the contract turns it into a reliable routine.
Flat fee or time and materials: choosing the right contract model
In practice, two basic models have proven themselves, and they combine well.
- Flat-fee contract: A fixed amount per billing period covers a clearly described scope of work, such as an annual inspection with visual check, cleaning and function test. The customer knows what they will pay; the business carries the risk if the effort turns out higher than calculated.
- Time-and-materials contract: The contract secures the appointment and scope of work, while invoicing follows the actual working time and materials used. This is fair for systems whose effort is hard to estimate, but it makes costs less predictable for the customer.
- Combination: A base fee covers standard maintenance; repairs, spare parts and additional work are charged on a time-and-materials basis. This model combines predictability with fair invoicing of extra work.
Whatever the model, a precise description of services is essential: what counts as maintenance, what is a repair, which wear parts are included, and at which rates is additional work charged? The more clearly the contract draws this line, the fewer discussions arise over the invoice. Calculate the flat fee from real job times including travel, and review it regularly.
Recording intervals and inspection deadlines properly
How often a system is serviced depends on manufacturer specifications, recognised engineering practice, usage and, in some areas, legal requirements. These requirements are often addressed to operators or employers rather than to the trade business. A contract can, however, state that you keep track of the dates and carry out the work. Some examples from Germany (as of October 2026):
- Electrical installations and equipment in workplaces: the accident prevention regulation DGUV Vorschrift 3 (Section 5) requires regular inspections; the employer sets the intervals based on the risk assessment under the Industrial Safety Regulation (Section 3 BetrSichV).
- Lifts: the Industrial Safety Regulation (BetrSichV, Annex 2, Section 2) requires recurring inspections by an approved inspection body. Regular maintenance by a specialist business does not replace this inspection, but it prepares for it.
- Refrigeration and air-conditioning systems containing fluorinated greenhouse gases: the EU F-Gas Regulation (EU) 2024/573 (Article 5) governs leak checks, with intervals depending on the charge in CO₂ equivalent.
- Heating: measurements under the Ordinance on Small and Medium-Sized Combustion Plants (1. BImSchV) are carried out by the chimney sweep. Maintenance of the heat generator itself is mainly governed by the manufacturer's specifications.
Record in the contract which interval applies, where it comes from and who remains responsible for official or expert inspections. Austria and Switzerland have their own regulations; the basic idea – clearly defining interval, responsibility and proof – transfers directly.
Term and cancellation: rules for consumer customers
Many maintenance contracts run for one year and renew automatically. For consumer contracts based on pre-formulated terms, the German Civil Code sets limits: under Section 309 No. 9 BGB, the initial term may not exceed two years, the notice period before it ends may not exceed one month, and a tacit extension is only permitted for an indefinite period with a notice period of no more than one month (version in force since 1 March 2022). If you let consumers conclude such contracts via your own website, Section 312k BGB additionally requires a cancellation button there.
With business customers there is more leeway, but term, renewal, notice period and price adjustment should still be clearly regulated. A price adjustment clause must be transparent and balanced; if in doubt, have your template contracts reviewed.
Scheduling appointments in good time instead of chasing deadlines
The most common weak point in the maintenance business is not the contract but the scheduling. If due maintenance only comes to light when the customer calls, the benefit of predictability is lost. A fixed lead time works well: the maintenance job is created a few weeks before the due date so the office can agree it with the customer and fit it sensibly into route planning.
Group maintenance visits geographically and place them deliberately in quieter periods. Heating maintenance, for example, can be moved into late summer and early autumn, before fault reports increase. Plan realistic job times per system and a buffer for findings that can be fixed on the spot. Our article Workforce Scheduling for the Trades explains how date-based planning of teams and vehicles works.
How ManoPlan supports recurring maintenance
In ManoPlan, you create maintenance contracts per customer: with a term, a status (active, paused or ended), a service interval in months, the next service date and an estimated job duration. One contract can cover several of the customer's systems. A lead time in days determines how far ahead of the due date a maintenance job is created. This job is created automatically and can then be scheduled like any other job.
For flat-fee contracts, you can optionally store a billing interval and an amount. ManoPlan then creates a draft invoice for each billing period that falls due. The draft is not sent automatically: your office reviews it and sends it deliberately. Additional work on a time-and-materials basis can be invoiced separately from the job, optionally from logged working time and consumed materials. The contract overview shows key figures for your contracts and can be filtered.
Invoicing: keeping mandatory details and periods in view
Whether flat fee or time and materials, every invoice needs the mandatory VAT details under Section 14(4) UStG, including the date or period of the service. For recurring flat fees, it should therefore be clear which period is being invoiced. For invoices to businesses in Germany, the e-invoicing rules also apply (Section 14(1) UStG with transitional provisions); our article E-Invoicing for Trade Businesses gives an overview.
Agree whether flat fees are invoiced in advance or in arrears, and ask your tax adviser how advance payments are treated for VAT purposes. Invoice additional work promptly after the visit. Record in the maintenance report what was done and which defects were found – this is the basis for queries and follow-up quotes.
Customer loyalty: maintenance as a foundation for trust
A maintenance customer who is looked after reliably will call you first when something breaks and ask you first about a modernisation. This loyalty does not come from the contract alone but from the quality of each visit: timely notice, a technician who knows the system, an understandable report and an invoice without surprises.
- Announce appointments early and offer alternatives
- Explain findings clearly and put recommendations in writing
- Keep system data such as type, year of manufacture and serial number up to date
- Check briefly after the visit that everything is working
- Review and adjust the contract together once a year
Checklist: setting up your maintenance business for the heating season
- Record all existing maintenance customers and serviced systems
- Describe the scope of work per system type in writing and separate it from repairs
- Choose a contract model: flat fee, time and materials or a combination
- Calculate flat fees from real job times including travel
- Document intervals, legal bases and inspection responsibilities per system
- Align term, renewal and cancellation for consumers with Section 309 No. 9 BGB
- Set a scheduling lead time and group maintenance visits by region
- Define the billing interval, mandatory details and approval of draft invoices
- Standardise the maintenance report with findings and recommendations
- Review the contract portfolio and pricing at least once a year
This article is not legal or tax advice. The regulations mentioned reflect the situation as of October 2026. Check the requirements that apply to your business, your systems and your country against the current legal texts and with your legal or tax adviser.
Conclusion
Maintenance contracts smooth out workload, make revenue more predictable and keep customer relationships alive. Success depends less on the contract template than on a reliable process: a clear scope of work, documented intervals, appointments planned early and invoices the customer can follow. Starting at the beginning of the heating season builds a pillar that carries the business through quieter months too.