Time and materials or fixed price: what it means, when to choose which, and what to put in writing
A customer calls about a leaking water heater and immediately asks what it will cost. The technician will only know once they have opened the unit. An hour later, another customer asks for a price for a new heat pump, and they want to hear one amount, not an hourly rate.
Published by Abdelhay Rahou (opens in a new window)5 November 202611 min read
Time and materials: what it means
Working on time and materials (regie / régie) means the customer pays what the work really takes: the hours worked at an agreed hourly rate, plus the parts and the travel. With a fixed price (forfait), you agree one fixed price in advance for a described piece of work, however long it takes. Time and materials suits breakdowns, a fixed price suits work you can describe in advance.
In Belgium, the term regie is sometimes also used for staff who go to work at another company. This article is about time and materials as a way of agreeing a price.
What time and materials and a fixed price mean for the customer and for you
On time and materials, the customer knows the hourly rate and an estimate, but the final price only afterwards. If the work turns out harder than expected, they pay the extra hours. You must then be able to show every minute and every part.
On a fixed price, the customer knows the price in advance and can compare. You carry the risk: if it takes longer, you pay for the extra hours; if it goes faster, you keep the margin.
So time and materials says something about how you calculate the price. Who is liable for what if something goes wrong is a different question: put it to your legal adviser and your insurer.
Time and materials or fixed price: which to choose for each type of work?
A starting point to adapt, not a rule:
| Type of work | Usually | Why |
|---|---|---|
| Breakdown or repair | Time and materials, with an estimate | The cause is only known once the technician is on site |
| Small job of less than an hour | Time and materials, with a minimum billed time | A trip and a slot in the schedule cost money even for ten minutes of work |
| Maintenance visit | Fixed price or contract price | You know the work and do it often |
| Installing a unit | Fixed price on a quote | The customer wants one price, and you can look at the work in advance |
| Work with unknowns, such as old pipes inside a wall | Fixed price for what you can see, time and materials for what you cannot | That way the risk stays where it belongs |
| Additional work during a fixed-price job | A separate price, accepted in writing in advance | The fixed price only covers what was described |
How to build a fixed price from your hourly rate, with estimated hours, travel, parts and a reserve, is explained in calculating a technician’s hourly rate.
What do you put in writing for time and materials?
- The hourly rate, excluding VAT, and the unit you charge in: per hour, per half hour or per quarter of an hour.
- A minimum billed time per intervention, if you use one.
- Travel: which model and what amount. See charging travel costs.
- Parts: at what price they are charged.
- Surcharges for evening, weekend or urgent work, if you charge them.
- An estimate: the estimated number of hours and the main parts.
- What happens if the estimate is not enough, for example: “If the estimate is exceeded by more than [x], we will call you before we continue.”
In its notice of 14 August 2026, the FPS Economy (FOD Economie / SPF Economie) advises consumers always to ask for a written price estimate in advance. According to the same notice, additional costs, such as replacement parts, must be communicated to the consumer in writing before the repairer carries them out (FPS Economy, in Dutch). Have your terms checked by your legal adviser.
Carrying out time-and-materials work: keeping it transparent
- Record the hours as you go. Departure, arrival, start and end of the work, not in the evening from memory.
- Note every part when it is used, with the quantity.
- Write in the report what you found and what you did, and why it took longer than expected.
- Call before you exceed the estimate, and note the customer’s agreement.
- Have the customer sign for the hours and the parts on the work order.
- Invoice quickly, with the work order as supporting evidence. See from work order to invoice.
What do you put in writing for a fixed price?
- What is included: unit, materials, installation, removal of the old unit, commissioning, travel.
- What is not included, by name, and the assumptions behind your price.
- How you handle additional work: only after written agreement, with the price stated.
- Payment: deposit and instalments, if you ask for them.
How to word this on the quote, and what is mandatory on it for a consumer, is explained in writing a quote.
Protecting a fixed price: changes and additional work
A fixed price often loses its margin during the work, when the customer asks for “one more small thing” or the technician finds something that could not be seen. Agree a fixed procedure:
- The technician stops at anything outside the description and calls the office.
- The office gives the price, as a fixed amount or on time and materials.
- The customer accepts in writing, on paper or by email.
- Only then does the technician carry out the additional work.
An example of an agreement for additional work, to adapt:
Additional work on quote [number]: [description of the work]. Price: [amount] euros excluding VAT, or on time and materials at [hourly rate] euros per hour with an estimate of [number] hours. Customer’s agreement: [name], [date], [signature or confirmation by email].
After every fixed-price job, compare the actual hours with your estimate: that shows you which work you price too tightly.
Time and materials or fixed price: the differences in one table
| Comparison | Time and materials | Fixed price |
|---|---|---|
| The price | Hours times the hourly rate, plus parts and travel | One amount for a described piece of work |
| The customer knows the price | Afterwards, with an estimate in advance | In advance |
| Who carries the risk of setbacks | The customer | You |
| What must be in writing | Rates, estimate, what happens if it is exceeded | Description, exclusions, assumptions, additional work |
| What supports the invoice | Hours and parts on a signed work order | The accepted quote and the accepted additional work |
| Where disputes arise | The number of hours | What was included |
| Suits | Breakdowns, small repairs | Maintenance, installations |
An example: one heating company, three kinds of work
A fictitious heating company works in three ways in one week.
On Monday, a boiler breaks down. The office states the hourly rate and the travel, estimates one to two hours plus parts and promises to call if it will be more. The technician records their hours, notes the igniter they replace and has the customer sign. The invoice follows from the intervention.
On Tuesday, a maintenance visit is scheduled at a customer with a contract. The visit is included in the annual price, which was invoiced in January.
On Wednesday, the installation of a heat pump starts, at a fixed price on an accepted quote. The technician finds a rusted valve that was not on the quote and calls the office, which sends the customer a price. Only after the confirmation by email is the valve replaced. The invoice contains the lines of the quote and the additional work, and afterwards the business owner compares the actual hours with the estimate.
Short video · 0:30
Wel gewerkt, maar niet gefactureerd?
Elke stap van de interventie krijgt zijn tijd en gebruikte onderdelen worden meteen geboekt. Op kantoor staan uren en onderdelen klaar voor de factuur.
Video in Dutch, with Dutch captions
All short videos (in Dutch)How it works in Digitalnatie Service Suite
A time-and-materials repair starts from the recorded hours and parts, a fixed-price installation from the confirmed quote. Every invoice stays a draft until you check it, post it and send it in invoicing.
On time and materials
- Hours: in the technician app, the technician taps depart, arrived, start work, break and end work. After closing, the intervention’s times show the travel time, the break and the working time; at the office, the intervention form shows the actual times recorded.
- Parts: the technician records them in the parts tab with add, from the stock in their van.
- Report and signature: in the work tab, the intervention report (work done, problem found, solution), and under signatures, the customer and the technician. The fully completed result requires both signatures, or a reason, and the mandatory photos.
- Invoice: on a completed intervention, accounting uses create invoice to make a draft invoice with the billable hours, at the hourly rate excluding VAT and the minimum billed time per intervention set in the organisation settings, and the parts used.
On a fixed price
- Quote: in quotes (under the sales and invoicing menu), new quote, with product lines, section titles and notes, and for each line the price from the price list or your own price.
- After the agreement: confirm turns the quote into a sales order. From that order, create intervention or create project starts the work, and invoice creates a draft invoice with the agreed lines, prices and discounts.
- Additional work: a new quote, or a line on the draft invoice by editing the lines, with add product or a free line.
- Costing afterwards: the intervention form shows the estimated duration and the actual times. In reports (under the insights menu), the technicians tab gives the hours worked and the billable hours per technician, with a CSV export.
With a maintenance contract: create annual invoice, on an active contract, makes the draft invoice for the calendar year at the annual price. For each contract, you set whether the visit, the hours above the minimum and the parts are billable or included in the contract. See also drawing up a maintenance contract.
Good to know:
- If an intervention is linked to a confirmed sales order, its invoice takes over the lines and prices of that order, plus the parts used that are not on it, at their sale price. If that material is included in your fixed price, delete those lines from the draft invoice before you post it.
- A confirmed sales order can no longer be changed in the application. For a correction, ask Digitalnatie.
- The settings hold one hourly rate and one minimum per intervention. A different rate, for example for urgent work, is adjusted by accounting on the draft invoice.
- The office cannot add used parts to an intervention: the technician records them in their app.
- You send a quote yourself as a PDF, and requesting a signature from the application is not possible.
- The application and the guide are available in Dutch, French and English.
Frequently asked questions
What does time and materials mean?
Time and materials means you charge the hours actually worked at an agreed hourly rate, plus the parts used and the travel. The customer knows the rate and an estimate in advance, but the final price only after the work.
What is the difference between time and materials and a fixed price?
On time and materials, the customer pays the actual hours and parts, and carries the risk if the work turns out harder than expected. With a fixed price, you agree one price in advance for a described piece of work, and you carry the risk of extra hours yourself. Additional work outside the description is not covered by the fixed price.
When is a fixed price the better choice?
When you can look at the work and describe it in advance, such as a maintenance visit or installing a unit. Build the price from the estimated hours at your hourly rate, plus travel, parts and a reserve, and write down what is not included.
What if time-and-materials work costs more than the estimate?
Agree in advance at what overrun you will call the customer, and only continue after their agreement. Note that agreement and the reason for the extra hours in the report, so the invoice can be explained.
Can Service Suite invoice on time and materials and at a fixed price?
Yes. A completed intervention becomes a draft invoice with the billable hours and the parts used. A confirmed quote becomes a sales order, from which you create a draft invoice with the agreed lines and prices. A maintenance contract gets an annual invoice at the annual price.