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With a fixed price, the cost is set upfront for a defined scope and the provider carries the overrun risk; with time and materials, you pay for the time actually spent and carry that risk. For a well-scoped business app at $6,800 to $22,400 (€6,000–€20,000)excl. VAT, fixed price is usually safer; time and materials suits later changes.
Even before the price, the billing model tells you a lot about a project: who carries the risk if development takes longer than planned? With a fixed price, the provider does. With time and materials, you do. Here is how both models work, when to choose each one, and how I combine them.
The two models in brief
Fixed price: a precisely described scope, a price set upfront, a schedule. If the work takes longer than expected, the price does not change. If you add requests, they are quoted separately.
Time and materials: you pay for the hours or days actually worked, at an agreed rate. The scope can change freely, but the final cost is only known at the end.
| Criterion | Fixed price | Time and materials |
|---|---|---|
| Price | Set upfront | Known at the end |
| Overrun risk | Carried by the provider | Carried by the client |
| Scope flexibility | Changes through amendments | Changes at will |
| Scoping needed | Essential | Desirable |
| Client-side oversight | Approving each batch | Regular review of time spent |
| Best for | Projects with a clear scope | Changes, maintenance, exploration |
Why I work on a fixed-price basis for projects
My build projects are offered at a fixed price: a business app at $6,800 to $22,400 (€6,000–€20,000)excl. VAT, a custom ERP at $16,800 to $56,000 (€15,000–€50,000)excl. VAT. The reasoning is simple: a CFO should be able to put an amount in the budget and stick to it.
A fixed price only works with serious scoping. That is why every project starts with a 1 to 2 week phase that produces a requirements document, a fixed quote and a schedule. Clickable mockups then confirm the scope before the first line of code. The guide on writing an app requirements document explains what that document should contain.
Payment follows progress: a 50% deposit at the start, then the balance according to the schedule in the quote.
When time and materials is the right model
Time and materials has real use cases. It fits when:
- the need is exploratory: testing an idea, a first AI use case, a proof of concept;
- requests are small and frequent: fixes, tweaks, small improvements after go-live;
- you need occasional expertise: reviewing an architecture, advising an in-house team. My coaching and technical expertise are billed at $170 (€150)excl. VAT per hour;
- the scope cannot be described in advance, for example when taking over a project whose state is still unknown. In that case, I first suggest an audit at a fixed price, then a quote.
The pitfalls of each model
With a fixed price:
- A vague scope. A fixed price based on a fuzzy requirements document leads to disputes about what was “included”. Insist on a precise description of screens and rules.
- An unusually low price. The provider may make up for it by refusing any adjustment or delivering minimum quality.
- The tunnel effect. Without intermediate deliveries, you discover the result too late. Insist on testable batches.
With time and materials:
- No cap. Set a budget and an alert threshold.
- No visibility. Ask for timesheets by task.
- No incentive to finish. Set dated objectives, even on time and materials.
The most common causes of overruns are covered in why software projects overrun.
The most common combination
In practice, most projects combine both:
| Stage | Billing model |
|---|---|
| Audit or scoping | Fixed price |
| Building the first version | Fixed price on a firm quote |
| Three months after go-live | Support included in the fixed price |
| Maintenance | Fixed fee or hourly |
| New features | Quote per request, or hours |
This combination gives you a predictable budget for the heaviest part, and flexibility afterward. To estimate the fixed-price part, the estimator gives you a range in one minute.
When a fixed price does not fit
A provider cannot honestly commit to a fixed price when the scope is impossible to describe, or when an existing project has to be taken over without knowing its state. That is why I quote the takeover of a project built with AI or no-code only after an audit.
In these cases, an audit or a few hours on time and materials to remove the uncertainty costs less than a fixed price inflated to cover the unknown.
Where to start
- Describe your need on one page: goals, users, current tools.
- Book a free 30-minute discovery call: I will tell you whether a fixed price is possible right away or whether an audit should come first.
- Approve the scoping, then the fixed quote.
Payment terms and the full price list are on the pricing page.
Frequently asked questions
Is a fixed price more expensive than time and materials?
A provider builds some risk into a fixed price, since they commit to the amount. But time and materials without proper scoping often drifts beyond the initial estimate. With a clear scope, a fixed price rarely ends up costing more, and it is predictable.
What happens if I change my mind during a fixed-price project?
Changes to the approved scope go through an amendment or an additional quote, which you accept before the work is done. Clickable mockups exist precisely so these changes happen before development, when they cost little.
How do you keep time and materials under control?
Ask for a detailed timesheet by task, a monthly cap beyond which the provider must alert you, and regular demos of what has been built. Without these three safeguards, you pay for hours with no visibility on the result.
Does a fixed price include maintenance?
Usually not. The fixed price covers the delivered scope and a support period. With me, three months of support are included after go-live; maintenance and new features are then billed as a fixed fee or by the hour.