The choice between a fixed price and time and materials, settled as early as the quote, shapes everything that follows on a web project: who carries the risk of a poorly scoped brief, how a mid-project addition gets negotiated, and the moment a disagreement over price turns into a disagreement over trust. That choice is not just about billing: it shapes the relationship between developer and client for the whole duration of the project.
Fixed price and time and materials: two ways of allocating risk
A fixed price sets a total amount for a scope defined in advance: the client knows the final figure before production starts, and the provider commits to delivering that scope for that price, regardless of how much time it actually takes. Time and materials, known in French as régie, bills for the time actually worked, usually through a day rate: the client pays for what gets produced, and the provider does not carry the risk of a workload overrun. Neither model is better in the abstract: one simply fits the nature of a given project better than the other.
Fixed price: a bet on a locked scope
Fixed price works well when the scope can be described precisely: a showcase site with a known number of pages, an e-commerce integration on a stable catalog, a technical migration whose size can be measured ahead of time. In those cases, a well-structured quote lets both sides price the risk correctly, and the fixed price protects everyone: the client against a billing overrun, the provider against a constant renegotiation of the price. Fixed price turns dangerous the moment the scope is still fuzzy at signature: every ambiguity in the brief then either eats into the provider’s margin or quietly shrinks the delivered scope to hold the price, which the client always ends up noticing.
Time and materials: flexibility against budget visibility
Time and materials fits naturally on projects whose scope keeps evolving: a SaaS product still being built, a redesign driven by user feedback, an ongoing maintenance and evolution engagement on an existing codebase. The client loses visibility on the final total, but gains the ability to re-prioritize without renegotiating a contract every time direction changes. For the provider, time and materials removes the risk of underestimating a workload, provided the day rate actually reflects the level of skill involved, something plenty of freelancers, especially those who have not revisited their rates in years, tend to undersell.
Setting a day rate that actually holds up
Time and materials only protects the provider if the day rate applied covers what it actually needs to cover: billable time is never equal to worked time. Between prospecting, admin, ongoing training and quiet stretches, a freelancer who assumes they can bill 20 full days every month almost always overestimates their real capacity across the year. A day-rate calculation that ignores that gap ends up, over time, producing an annual income well below the target, even with a full pipeline of work.
A simple benchmark is to start from the targeted annual revenue, add the business’s fixed overhead, then divide by a realistic number of billable days, often somewhere between 130 and 160 per year once holidays, prospecting and admin are stripped out, rather than the 220-odd working days on a calendar. The rate that comes out of that calculation is almost always higher than the one kept out of habit, especially among freelancers who have not revisited their rate in years despite genuinely growing more skilled. Time and materials makes that gap visible month after month; a fixed price tends to hide it behind a total that looks reasonable at the moment of signing.
The hybrid model: fixed-price scoping, then time and materials
In practice, most web projects do better combining both logics rather than picking one over the other. A scoping and design phase can be billed at a fixed price, with a clear deliverable (specifications, mockups, technical architecture) that then becomes the basis for a reliable estimate. The build phase can then switch to fixed price if the scope that comes out of that phase is precise enough, or stay on time and materials if the project needs to keep its flexibility. This split avoids the classic trap of a fixed price signed against a still-fuzzy brief, where the provider prices blind and the client discovers the real scope only after signing.
| Criterion | Fixed price | Time and materials |
|---|---|---|
| Visibility on the final price | Known at signature | Depends on time actually spent |
| Who carries overrun risk | The provider | The client |
| Scope flexibility | Low, needs a formal amendment | High, priorities adjustable in real time |
| Upfront scoping needed | High | Low to moderate |
| Typical use case | Showcase site, technical migration, e-commerce integration | Evolving product, ongoing maintenance, long-running engagement |
Contract clauses that prevent disputes
Whichever model is chosen, a few clauses limit the risk of a dispute mid-project. A fixed-price contract should always spell out the exact scope covered, the number of included review rounds, and above all the process for handling an out-of-scope request: without an explicit amendment clause, every informal addition quietly eats the provider’s margin without ever being billed. A time and materials agreement, for its part, benefits from stating an indicative hourly or daily volume per period, so the client keeps a minimum of budget visibility without losing the model’s flexibility. Either way, a regular billing checkpoint, monthly at a minimum, stops a price disagreement from surfacing only at the end of the project, exactly when it is most expensive to resolve.
A fixed price signed against a still-fuzzy scope almost never protects the client: it pushes the provider to cut corners on quality or detail to hold a price set on shaky assumptions.
Before choosing fixed price or time and materials, check that the brief passes a simple test: could it be handed to a different provider without losing information? If the answer is no, the scope is not tight enough for a reliable fixed price.
What to remember
Fixed price suits stable, measurable scopes; time and materials suits projects whose direction is still open. The choice is made project by project, sometimes phase by phase within the same project, and is always secured with written clauses on how out-of-scope requests get handled. Neither model compensates for an imprecise brief: it only moves the point where that fuzziness ends up costing money.
After years of billing mostly at a fixed price, I gradually shifted a good share of my longer engagements to time and materials, especially on maintenance and ongoing-evolution work. Fixed price still earns its place on short, well-defined requests, but on anything running past a few weeks, it mostly served to let me underestimate my own workload. Time and materials demands discipline in return: a day rate kept too low out of habit rather than revised upward with experience ends up costing more over time than a badly priced fixed-price job — Simon Janvier.
Further reading: the legal framework for quotes on economie.gouv.fr (in French).
