Fixed price vs time and materials: how to actually pick

Fixed price sounds safer. You know the number before you start. Time and materials sounds open-ended. You are paying for hours and hoping the team is fast. Both impressions are half right, and both contracts can go badly wrong in the same week if you do not understand what each one rewards.

I have seen the same client love one model on one project and regret it on the next, because the model was not the problem. The fit between the model and the state of the requirements was.

What each model actually means

Fixed price means you agree on a scope and a number before anyone writes code. The vendor carries the risk if the work runs long, so they price that risk into the number. You carry a different risk: that what you described is not what you actually need, and that changing it will cost extra.

Time and materials means you pay for the hours worked against an agreed rate. The risk that the work runs long is yours. The ability to change direction without a new contract is yours too.

That is the whole trade. Fixed price buys you a budget, not necessarily a product you will like. Time and materials buys you the right to steer, and it asks you to pay attention while you do it.

One more thing before you choose: the rate and the estimate are not the same as the bill. Two teams can quote the same hourly rate and land a week apart, because one is faster and one is padding the calendar. The only number that matters in the end is the total for the outcome, which is why weekly demos matter more than the model printed on the contract.

Where fixed price goes wrong

Fixed price rewards the vendor for doing exactly what the contract says and charging for the rest. The moment you say we also need the export feature, you get a change order. Every small change becomes a negotiation, and the project slows to the speed of the paperwork. I have watched a three-week build turn into a three-month build because every new idea had to be quoted, approved, and re-scoped.

It also punishes you for not knowing your requirements yet. If you are a first-time founder writing a spec for something you have never built, a fixed price is a bet that your guesses are right. They usually are not, and you pay for the difference.

Where time and materials goes wrong

Time and materials goes wrong when the team is slow or the reporting is vague. You pay every week and get a sentence like continued working on the payment module. That is not a report. It is a receipt without an itemized bill.

The fix is not to avoid hourly billing. The fix is to make the team show work in small pieces every week, and to cap the risk with a budget number that triggers a conversation when it gets close. A weekly demo and a weekly burn number do more to protect you than any clause in a fixed-price contract.

How to pick

A rough rule I give clients: if you have built this kind of thing before and can write the spec in a day, fixed price is fine. If this is your first version, or the requirements are still moving, time and materials with a weekly demo and a hard budget ceiling beats a fixed price with a stack of change orders.

A second question worth asking is how the number was produced. A fixed price with no breakdown behind it is a guess wearing a suit. Ask the vendor to show the estimate line by line, and watch which lines they padded. The padded ones are the parts they are unsure about, and those are exactly the parts that will change on you.

You can also mix them. Fix the price on the part you know, bill the exploration hourly. A good vendor will be honest about which parts of your project fall on which side of that line. GlobeSoft runs both models, and the honest answer we give most first-time builders is to start hourly until the scope settles, then fix it. We have done this for clients in Brazil, South Africa, Singapore, and the US, and the pattern holds across time zones. A shared channel and overlap hours keep a time-and-materials project from drifting, because someone is watching the burn every day in English or Portuguese, not once a month.

Talk to us about your project