One of the first decisions you make when hiring a software development agency is how to structure the engagement. And it's a decision that shapes everything that follows — your budget predictability, your flexibility to change direction, your exposure to risk, and how the agency is incentivized to behave.
There are three main models: fixed price, time and materials, and dedicated team. Each one is genuinely right for some situations and genuinely wrong for others. Agencies have preferences — usually based on what's most profitable for them rather than what's best for your project. That means you need to understand the models well enough to push back when an agency steers you toward the wrong one.
I'll give you the honest version of each.
Fixed Price
What it is
You agree on a scope. The agency quotes a price for that scope. You pay that price (usually in milestones) regardless of how long it actually takes the agency to deliver.
What it looks like in practice
You provide detailed requirements. The agency reviews them, asks clarifying questions, and produces a proposal: "We will build X, Y, and Z for $45,000, delivered in 16 weeks." You sign. The agency builds. You pay at defined milestones — typically something like 30% upfront, 40% at midpoint, 30% on delivery.
When fixed price is the right choice
When requirements are genuinely well-defined. The entire logic of fixed price rests on the assumption that both parties understand what's being built. If you can write down, in enough detail that a stranger could understand it, exactly what the software needs to do — user types, features, workflows, integrations, edge cases — fixed price works.
When budget predictability matters more than flexibility. If you have a fixed budget and cannot overrun it, fixed price gives you a ceiling. You know the maximum you'll spend.
When the project is relatively short. The longer a project runs, the more likely requirements will evolve. Fixed price works better for 8–16 week engagements than for 12-month ones.
When scope is genuinely stable. If you've done enough product thinking, user research, and market validation that you're confident in what you're building, fixed price rewards that preparation.
When fixed price goes wrong
When requirements aren't as clear as you think. Most founders believe their requirements are clear. Most agencies discover during development that they aren't. The gap between what you meant and what you wrote becomes a negotiation about change orders — and change orders are how agencies make money on fixed price projects.
When you need flexibility. Building a product is an iterative process. You learn things from early users that change what you build. Under fixed price, every change is a negotiation. This slows you down and creates friction at exactly the moment you need to move fast.
When the agency uses fixed price to underbid. Some agencies win fixed price contracts with a low quote, then make their margin on change orders. This is the most common way fixed price projects go over budget — not because the work expanded, but because the original quote was designed to win the contract, not to reflect the actual cost.
Warning sign: A fixed price quote that arrives within 48 hours of your requirements document, with no clarifying questions. Real requirements analysis takes time. A fast quote usually means the agency skimmed the requirements and padded the number.
The change order problem
Change orders are the defining challenge of fixed price engagements. Every time you want something that wasn't explicitly in the original scope — even something small — the agency can legitimately charge extra.
This creates a perverse incentive. The agency is rewarded for finding scope gaps, not for solving your problem. The client is punished for learning — every insight that changes the product costs money.
If you go fixed price, invest heavily in the requirements document before signing. The time spent on requirements definition is the cheapest time in a fixed price project.
Time and Materials (T&M)
What it is
You pay for actual time spent, at an agreed hourly or daily rate. The agency tracks hours and invoices accordingly — weekly, biweekly, or monthly depending on what you agree.
What it looks like in practice
You agree on team composition (e.g., 2 senior developers + 1 QA engineer) and hourly rates ($45/hr per developer, $35/hr for QA). You get a rough estimate of hours for the project. The agency tracks time and invoices against actual hours. Final cost depends on actual time spent.
When T&M is the right choice
When requirements will evolve. If you're building something new, with genuine uncertainty about what the right product looks like, T&M lets you respond to what you learn. You can pivot without a change order negotiation.
When you want ongoing development. Continuous product development — new features, bug fixes, iterations based on user feedback — doesn't map well to fixed price. T&M is the natural model for sustained development partnerships.
When you trust the agency. T&M requires confidence that the agency is working efficiently and honestly tracking time. If you don't trust them to do that, T&M gives you limited recourse. Build trust through smaller fixed price engagements first, then move to T&M for ongoing work.
When speed matters. Fixed price creates process overhead — change order negotiations, scope discussions, approval cycles. T&M removes most of that friction. You want a new feature? It goes on the sprint. No negotiation required.
When T&M goes wrong
When scope is genuinely undefined. T&M without any scope definition is a blank check. You need some structure — a product roadmap, sprint goals, defined features even if specific implementations are flexible.
When you don't have the bandwidth to manage it. T&M requires active client involvement. You need to review work regularly, give clear feedback, make decisions quickly, and manage scope actively. Clients who disappear and then complain about cost at invoice time are the classic T&M failure mode.
When the agency isn't tracking time honestly. Time tracking fraud exists. It's not common among reputable agencies, but it's a risk. Regular code commits, sprint reviews, and visible progress are your protection.
When estimates are significantly wrong. T&M estimates are just estimates — the actual cost could be meaningfully higher. If your original estimate was $50,000 and you're at $75,000 with the project unfinished, you have a problem that requires a difficult conversation. Set a budget ceiling and require the agency to flag when they're approaching it.
The visibility requirement
T&M only works if you have clear visibility into what's being built and what it's costing. At minimum you need:
- Weekly progress updates with work completed and hours logged
- Access to the project management tool (Jira, Linear, Trello — whatever they use)
- Regular demos of working software
- A clear process for raising concerns about scope or pace
Dedicated Development Team
What it is
You hire a team from the agency — typically 2–5 developers, sometimes with QA and a PM — who work exclusively on your product for an extended period. You pay a monthly retainer for the team, regardless of specific deliverables.
What it looks like in practice
You engage an agency for a dedicated team: 2 senior full-stack developers and 1 QA engineer. The monthly cost is $12,000–$18,000 depending on team composition and location. The team works on your product every working day, attends your standups, uses your project management tools, and is effectively an extension of your internal team. Minimum engagement is typically 3 months, often longer.
When a dedicated team is the right choice
When you have ongoing, sustained development needs. A dedicated team makes sense when you have enough work to keep them busy consistently — typically 6+ months of product roadmap. If you have a 3-month project, a dedicated team isn't the right model.
When product velocity is critical. A dedicated team that knows your codebase, your users, and your business moves faster than a team that's onboarding to a new project. The investment in ramp-up time pays dividends over the engagement.
When you want a long-term partnership. The best dedicated team engagements are multi-year. The team becomes deeply embedded in your product, accumulates institutional knowledge, and functions like an internal engineering team. You get the capability of an in-house team without the overhead of hiring.
When you're scaling a product post-launch. Post-MVP, when you have real users and a real roadmap, a dedicated team gives you the consistent capacity to execute against it.
When you need team consistency. Under T&M or fixed price, agency teams shift between projects. Under a dedicated model, the same people work on your product every day. Consistency produces better code and faster iteration.
When a dedicated team is the wrong choice
When your project has a defined end point. If you're building a specific product to hand off or a short-term system with no ongoing development need, you're paying for team capacity you don't need after delivery.
When you don't have enough work. A dedicated team of 3 people needs 3 people's worth of work. If your roadmap is thin, you're paying for idle capacity.
When management bandwidth is limited. Dedicated teams require active management from the client side. You need to run sprints, prioritize the backlog, give feedback, and make decisions regularly. If you can't dedicate that time, the team will drift.
When budget predictability is critical. A monthly retainer is predictable in cost but not in output. You know what you'll spend but you can't guarantee exactly what you'll get. If your board or investors require output-based accountability, dedicated teams can be harder to justify.
The team continuity issue
One thing to always confirm with a dedicated team model: what happens when someone leaves? Developer turnover is real, and a "dedicated team" that rotates members every few months is just T&M with extra steps. Ask specifically:
- What's the agency's developer retention rate?
- What happens to your engagement if a team member leaves?
- What's the transition process?
- Is there a knowledge transfer guarantee?
Side-by-side comparison
| Factor | Fixed Price | Time & Materials | Dedicated Team |
|---|---|---|---|
| Budget predictability | High | Medium | High (monthly) |
| Flexibility to change | Low | High | High |
| Best for | Well-defined projects | Evolving products | Sustained development |
| Typical duration | 2–6 months | Varies | 6+ months |
| Client management needed | Low | Medium | High |
| Risk if scope unclear | High | Medium | Low |
| Risk if agency isn't trusted | Medium | High | High |
| Suitable for MVP | Yes (if defined) | Yes | Sometimes |
| Suitable for ongoing product | No | Yes | Yes |
How to choose
Work through these four questions in order:
Question 1: How well-defined are your requirements? If you can write a detailed spec that both parties agree on → fixed price is viable. If requirements will evolve significantly → T&M or dedicated team.
Question 2: How long is the engagement? Short (under 4 months), defined end point → fixed price. Medium (4–8 months), some flexibility needed → T&M. Long (8+ months), sustained development → dedicated team.
Question 3: How much can you manage the agency day-to-day? Minimal bandwidth for management → fixed price (less oversight needed). Regular but not intensive involvement → T&M. Can run an embedded team like an internal squad → dedicated team.
Question 4: What does failure look like for you? Worst case is budget overrun → fixed price. Worst case is building the wrong thing → T&M or dedicated team. Worst case is losing the team mid-project → dedicated team with retention guarantees.
One honest thing about how agencies pitch these models
Agencies have preferences, and those preferences aren't always aligned with yours.
Fixed price is often preferred by agencies because it lets them optimize for profit — build fast, cut corners on edge cases, charge for changes. It also lets them maintain more control over the delivery process.
T&M is often preferred by agencies because it reduces their risk — if the project takes longer than expected, you pay for it. This isn't necessarily bad, but it means the agency's incentive is hours spent, not problems solved.
Dedicated teams are preferred by agencies because they provide predictable, recurring revenue. This aligns well with your interests when you genuinely need sustained development — but it's not right for every situation.
The right model is the one that matches your actual situation. If an agency pushes hard for a specific model without explaining why it fits your project, ask them to justify it in terms of your requirements, not theirs.
At Teamseven we use all three models. Fixed price for well-specified projects where the client wants cost certainty. T&M for product development where flexibility matters more than cost predictability. Dedicated teams for clients who need consistent engineering capacity over time. We'll tell you which we think fits and why — and we'll tell you if we think you're asking for the wrong model.
Muhammad Nabeel is the co-founder of Teamseven, a software development agency in Lahore, Pakistan. We've been working with startups and enterprises since 2017 across all three engagement models. Get in touch if you want to talk through which model fits your project.