What is a fixed-price contract?
A fixed-price contract sets one price for one written scope before work starts. The supplier carries the risk of the work taking longer than planned, and the client carries the discipline of deciding what's in scope up front. If the scope changes, the price changes by agreement, not by surprise.
What is a time and materials contract?
A time and materials contract charges for the hours worked at an agreed rate, plus any direct costs, usually billed monthly. The client carries the risk of the work taking longer, and gets the freedom to change direction at any time. Good versions have a weekly budget cap and regular reporting; bad ones have neither.
What is the difference between fixed price and time and materials?
The main difference between fixed price and time and materials is who carries the risk when the work takes longer than expected:
- Cost certainty: fixed price gives one known number. Time and materials gives an estimate that can grow.
- Who carries the overrun: the supplier on fixed price, the client on time and materials.
- Flexibility: time and materials lets you change direction freely. Fixed price needs each change priced and approved.
- Up-front work: fixed price needs a clear scope first. Time and materials can start with less.
- Incentives: fixed price rewards finishing efficiently. Time and materials pays for hours, so efficiency has to come from trust and oversight.
- Your involvement: fixed price needs decisions early. Time and materials needs someone watching the budget every week.
Neither is better in general. Each fits a different kind of work.
When is fixed price the right choice?
Fixed price is the right choice when you can describe the outcome and need to protect a budget. That covers most first versions:
- A SaaS MVP with one defined workflow.
- A website, or a clearly bounded rebuild.
- A funded team with a set amount to spend and a date to hit.
- A buyer who needs one number to get approval.
The common objection is that software scope can't be known in advance. For a whole product roadmap that's true. For a first version it's the discipline you want, because deciding what's excluded is most of what makes an MVP an MVP.
When is time and materials the right choice?
Time and materials is the right choice when the work can't be scoped because you don't yet know what it is:
- Ongoing development on a live product.
- Open-ended research or debugging, where the answer shapes the next step.
- A team that wants to reprioritise every week.
- Taking over an unfamiliar codebase, before anyone can say what's in it.
It works best with a trusted team and someone on your side who owns the budget.
Why do we use fixed price for SaaS MVPs?
We use fixed price because a first version needs a boundary, and a written scope gives it one. You get one number and a timeline before anything starts, and the exclusions are on paper, so neither side discovers a disagreement in month three. Our SaaS MVP cost guide walks through how that quote works.
After launch the work changes, so the model changes too. A product with paying customers needs flexible priorities, which is why most teams move to a monthly retainer for ongoing work. That's the same pattern we use across our services: fixed scope to get something live, then flexible capacity once there's something to learn from.
How do you make a fixed price work?
A fixed price works when the scope is specific enough that both sides would describe the finished product the same way. Three things make that happen:
- List the exclusions. A scope that only says what's included leaves everything else open to argument.
- Describe outcomes. "A customer can invite a colleague and assign a role" is testable. "User management" isn't.
- Agree how changes are handled. Price each change and approve it before building. That protects both sides and keeps changes deliberate.
A clickable prototype helps too. It's much easier to fix a price against screens people have tested than against a paragraph.
Common questions
Is fixed price or time and materials cheaper for software?
It depends how predictable the work is. On well-understood work, time and materials can cost less because no risk premium is built in. On a first version where scope tends to grow, fixed price often costs less overall because the overrun isn't yours and the scope stays controlled.
Can you combine fixed price and time and materials?
Yes, and it's a common pattern. A paid discovery or fixed first version sets the foundations, then ongoing work moves to a retainer or hourly model. That gives you cost certainty when the unknowns are largest, and flexibility once the product has real users.
What is a capped time and materials contract?
It's a time and materials contract with an agreed upper limit. You pay for hours worked up to the cap, and the supplier absorbs anything beyond it or stops to renegotiate. It sits between the two models, though a low cap can bring the same pressures as a tight fixed price.
Does fixed price lead to lower quality?
It can, if the scope is vague and the supplier cuts corners to protect its margin. A clear scope, named engineers, working software at regular demos and agreed quality standards such as tests prevent that. Ask to see those in the proposal, because the contract model alone guarantees neither quality nor failure.