Fixed price vs time and materials for a software project
Fixed price suits well-defined scope and time and materials suits work that will change. Many teams do best with a hybrid: a fixed-scope first sprint, then an ongoing team.
Choose a fixed-price contract when the scope is clear and unlikely to change, and time and materials when you expect to learn and adjust as you build. Many projects fit neither extreme, so a hybrid works well: a fixed-scope first phase to remove uncertainty, followed by an ongoing team that works in short cycles.
The model matters less than the terms inside it. A fixed-price deal with vague acceptance criteria is worse than a well-run time and materials engagement.
The two models side by side
Fixed price means the builder agrees to deliver a defined scope for a set price, usually against a statement of work that lists deliverables and acceptance criteria. Time and materials means the buyer pays for effort actually spent, often with a cap or a regular budget check-in.
| Aspect | Fixed price | Time and materials |
|---|---|---|
| Cost | Known up front | Follows effort spent |
| Scope | Locked; changes are paid requests | Can move between cycles |
| Who carries risk | Builder, if they underestimate | Buyer, if work runs long |
| Buyer risk | False certainty, padding, thin testing | Cost drift without a cap |
| Builder risk | Scope creep, slow approvals | Disputes over hours, shifting priorities |
| Best for | Bounded, well-understood work | Exploring, staged, ongoing work |
Two risks deserve a closer look.
- Change friction. On fixed price, anything outside the contract needs negotiation, which discourages you from adjusting course when you learn something.
- Visibility. On time and materials, you need working software and regular reviews, or hours become a poor proxy for value. A flexible contract does not replace product decisions.
When each one fits
| Question | Fixed price fits when | Time and materials fits when |
|---|---|---|
| Scope | Written in detail and stable | You are exploring and it will change |
| Integrations and data | Known and accessible | Discovered along the way |
| Shape of work | A bounded module, audit or migration | Staged delivery or an ongoing roadmap |
| Priorities | Settled for the duration | You want to reprioritize every cycle |
Hybrid options that work
The most practical structures combine both. A common pattern looks like this.
- 01Fixed-scope sprintreal output, clearer plan
- 02Reviewdecide the next step
- 03Ongoing teamshort cycles, regular cadence
- 04Retainerfixes and next features
Other combinations are worth knowing.
- Fixed price per milestone. Break a larger project into milestones, each priced and accepted separately. You re-plan between milestones.
- Time and materials with a cap. Hours are billed as worked, but a ceiling and a regular review protect the budget.
Contract terms that matter more than the model
Whatever model you pick, check these.
| Term | What to confirm |
|---|---|
| Acceptance criteria | Testable: what the user can do, where, with what data |
| Change requests | How a change is raised, estimated, approved, and by whom |
| IP transfer | You own the code you paid for, and when it transfers |
| Payment schedule | Tied to milestones or accepted work, not only dates |
| Warranty and support | A defined period for free defect fixes, then support terms |
| Exit terms | How either side can end it, and what you receive |
| Data and security | Who protects data; a business associate agreement for health data |
On IP, also check how third-party and open-source components are handled, and that you receive source code, documentation and access to repositories and environments.
Before you sign, check that:
- Acceptance criteria are written in testable terms, with a review period
- The change-request process names who can approve
- The contract states when you own the code and assets
- Payments follow milestones or accepted deliverables
- Defect warranty and exit terms are defined
- You will see working software regularly, whichever model you choose
How this looks at Techdome
Our studio offers fixed-scope sprints from $8,000. We also run dedicated engineering pods for ongoing delivery. Together these map to the hybrid above: a bounded first piece of work, then a team when the product needs continuous development.
Client work shows the pattern. For a US conversational AI venture, a $10K commercial sprint delivered in 2 to 3 weeks and reached production. For a multi-vendor telehealth care ecosystem, the case study records a follow-on statement of work with a 13-day turnaround. For an enterprise cloud platform provider, a long-term retainer ran for 11+ months. You can read more on our MVPs and venture studio page.
Takeaways
- Fixed price fits stable, well-defined scope; time and materials fits work that will change.
- A fixed price on vague scope only fixes the price of the wrong thing.
- A fixed-scope first sprint followed by an ongoing team is a common and practical hybrid.
- Acceptance criteria, change requests and IP transfer matter more than the label on the contract.
- Always ask for visibility: working software and regular reviews, whichever model you choose.
Have a project like this? Talk to our engineers.
