Two projects with the same budget can end very differently depending on how the contract is structured. The engagement model decides who carries the risk when requirements change, and in software, requirements almost always change.
Fixed price suits small, well-defined projects where scope is unlikely to change. Time and materials suits evolving products where you want flexibility and pay for the work actually done. A dedicated team suits long-term products that need a stable group of developers working as an extension of your own company.
How does each engagement model work?
Fixed price
You agree a defined scope, a price and a timeline up front. The development company carries the risk of the work taking longer than estimated. To manage that risk, the scope has to be detailed, and any change goes through a formal change request with a new estimate. Vendors also usually add a buffer to the price to cover uncertainty.
Time and materials (T&M)
You pay for the hours or days actually worked, usually at agreed rates per role, often with a monthly cap or a budget for each phase. Priorities can change from sprint to sprint without renegotiating a contract. You carry more of the budget risk, so transparency (timesheets, demos, a shared backlog) is essential.
Dedicated team
You reserve a team of specific people (for example two developers, a QA engineer and a part-time project manager) for a monthly fee. They work only on your product, follow your priorities and build deep knowledge of your codebase over time. You direct the work; the provider handles hiring, payroll, equipment and replacements.
How do the models compare?
| Factor | Fixed price | Time and materials | Dedicated team |
|---|---|---|---|
| Best for | Small, clearly defined projects | MVPs and evolving products | Long-term products and ongoing roadmaps |
| Scope flexibility | Low (changes need change requests) | High | High |
| Budget predictability | High for the agreed scope | Medium (use caps and phases) | High per month |
| Who carries overrun risk | Mostly the vendor | Mostly the client | Shared; client controls priorities |
| Client involvement | Mainly at start and at milestones | Regular, ideally every sprint | Daily or near-daily |
| Speed to start | Slower (detailed scoping first) | Fast | Depends on team assembly |
| Knowledge retention | Can be lost after delivery | Moderate | Strong |
When is fixed price the right choice?
Fixed price works well when you can describe exactly what "done" looks like: a marketing website with agreed pages, a defined integration between two systems, or a small app based on approved designs. It is also useful when your organisation needs a fixed budget approved in advance.
The catch is that fixed price can become rigid. If you learn something important halfway through, every change becomes a negotiation, and vendors may be tempted to deliver to the letter of the specification rather than to what users actually need.
When does time and materials make more sense?
Time and materials is usually the best fit for new products, because you learn as you go. User testing, early customer feedback or a competitor's move might change priorities, and T&M lets the team respond without paperwork. To keep the budget under control:
- Agree a monthly cap or a budget per milestone.
- Keep a prioritised backlog so the most valuable work happens first.
- Review a working demo every sprint and check progress against spend.
When should you hire a dedicated team?
A dedicated team makes sense once you have a product that will keep evolving for a year or more, or when you need to grow capacity without hiring locally. It works best when someone on your side (a product owner or CTO) can set priorities and review work regularly. Our guide to hiring dedicated developers in Bangladesh explains how this works in practice.
Can you mix models?
Yes, and it is often the most sensible approach. A common path is:
- Fixed-price discovery: a short, defined phase to produce user flows, designs and a prioritised backlog.
- Time and materials build: develop the MVP in sprints with a monthly cap.
- Dedicated team or maintenance plan: once the product is live and growing, move to a stable team or a support retainer.
What are the hidden costs of each model?
Every model has costs that do not appear on the first quote. With fixed price, the hidden cost is often the time spent writing a detailed specification and negotiating change requests, and the risk of receiving exactly what was written rather than what was needed. With time and materials, it is the management time you spend prioritising the backlog and reviewing progress, which is essential for keeping spend under control. With a dedicated team, it is the onboarding period and the need for someone on your side to direct the work every day. None of these are reasons to avoid a model, but they should be part of the comparison.
Questions to ask before you sign
- What exactly is included (design, QA, project management, deployment)?
- How are changes estimated and approved?
- How will I see progress and spend each week?
- What happens if a team member leaves?
- Who owns the code and accounts, and when does ownership transfer?
For a wider set of questions, see How to choose a software development company.
Key takeaways
- Fixed price trades flexibility for predictability and works best for small, stable scopes.
- Time and materials gives flexibility for evolving products, provided you use caps and regular demos.
- A dedicated team suits long-term products where continuity and deep product knowledge matter.
Not sure which model suits your project? We work in all three and will recommend the one that fits your scope and stage. Read how we work or request a quote to discuss your project.