Fixed price or time and materials: how to choose without regretting it
Published 17 February 2026
Every technology leader has sat in a meeting where someone asked "can we just get a fixed price for this?" It sounds like the safe option. Sometimes it is. Just as often, it is the more expensive path dressed up as certainty.
The honest answer is that neither model is better. Each one prices risk differently, and the right choice depends on who is best placed to carry that risk: you or your delivery partner.
What a fixed price actually buys you
A fixed bid transfers delivery risk to the vendor. You agree scope, milestones, acceptance criteria and a price, and the vendor commits to delivering that outcome regardless of how long it takes them. If the work runs over, that is their problem, not yours.
That transfer is not free. Any vendor pricing a fixed bid adds contingency, typically somewhere between 15 and 30 percent depending on how well the scope is defined. When the scope is genuinely stable, you are paying a fair premium for certainty. When the scope is vague, you are paying a large premium and you will still end up in change request negotiations, because the vendor priced what was written down, not what you meant.
Fixed price works well for platform implementations with defined requirements, migrations with a known source and target, integration builds against documented systems, and compliance-driven work with fixed acceptance criteria.
What T&M actually buys you
Time and materials transfers control to you. You direct the backlog, reprioritise as you learn, and pay for the effort consumed. There is no contingency premium because you are carrying the delivery risk yourself.
The common fear is that T&M is a blank cheque. It is only a blank cheque if nobody is watching. A well-run T&M engagement has transparent time reporting, agreed rate cards, regular delivery reviews and short notice periods for scaling the team down. If a vendor resists any of those, the problem is the vendor, not the model.
T&M suits ongoing enhancement backlogs, support arrangements, product development where requirements evolve sprint by sprint, and any programme where discovery is genuinely still happening.
The questions that decide it
Ask three things. First, how confident are you in the scope? If requirements are documented, agreed and unlikely to move, fixed price is buying real certainty. If the honest answer is "we will know more once we start", T&M avoids paying a premium for certainty that does not exist.
Second, who is better placed to manage the risk? If you have strong internal delivery governance, T&M keeps the contingency margin in your pocket. If you do not, a fixed bid puts accountability on a partner who does this for a living.
Third, what happens after go-live? Many programmes suit a hybrid: fixed bid for the defined build, transitioning to T&M for the enhancement and support tail. Structuring that from the start avoids repricing the relationship mid-flight.
Where people get burnt
The most common failure is choosing fixed price for poorly defined work. The project does not fail at the contract stage; it fails three months in, when every clarification becomes a variation and the relationship turns adversarial. The second most common failure is running T&M without governance and discovering the burn rate too late. Both failures are avoidable, and neither is an argument against the model itself.
Waverton delivers under both models, along with embedded specialists and fully managed services, so we have no incentive to steer you toward one. If you would like a straight recommendation on which fits your programme, request a quote and we will give you an honest answer, including when the answer is a model that earns us less.
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