Cost control when you're paying by the hour

Time-and-materials billing has an undeserved reputation for being a blank check where costs run wild. That’s only true if you manage it the way you’d manage a fixed-price project – meaning not at all until the final invoice arrives. With the right reporting and the right rhythm, time-and-materials gives you something fixed price can’t: predictable cost and the freedom to change your mind. The key is that cost responsibility is now yours, and you need tools to carry it.

Why the model is worth the trouble at all

A fixed price always includes a risk premium. The vendor doesn’t know exactly what’s coming, so they build in a margin for the unforeseen – which you pay regardless of whether it happens or not. Time-and-materials removes that premium: you pay for the work that’s actually done, no more, no less.

The price for that is that the risk shifts to you. If something turns out trickier than expected, it shows up directly on your invoice, not in the vendor’s margin. That’s why follow-up isn’t an administrative detail but the very condition for the model to pay off.

Require weekly reporting, in real time

The single most important habit is seeing the cost grow while it’s growing, not after the fact. Ask for a short report every week that includes:

• Hours logged since the last report, and what they went to.
• Remaining work for the current phase.
• Updated forecast against budget – are we on track, ahead, or behind?
• Deviations in a sentence or two: did anything unexpected come up?

Such a report takes the vendor a few minutes to write and gives you something invaluable: the chance to react in week three instead of being surprised in week ten. A vendor who can’t deliver that says something about their own foresight.

Set budget caps and decision points per phase

Divide the project into phases and give each phase a cap. The cap isn’t a commitment to a final price – it’s a trigger with a rule: as the team approaches the cap, they stop and check in before continuing. That turns “the money ran out” from an unpleasant discovery into a planned conversation.

At every phase boundary, you make an active decision: did we get what we paid for, and is the forecast for the next phase reasonable? That gives you the same exit points as a phased fixed-price model, but with a receipt for where the hours actually went.

Discuss deviations before they become invoices

The whole point of time-and-materials is that you can act in time. Use that. When a forecast starts to slip, have the conversation right away – while it’s still a forecast. Go through the cause: is it requirement creep on your side, an underestimate on theirs, or something genuinely unexpected? Different causes call for different responses.

Then you choose: add budget, reprioritize the scope so you get the most important things within the frame, or pause. The cheap part of the model lies right here – in a fixed-price project, the same slip would have become a dispute over what was included. Here, it becomes a decision you make together, in time.

A worked example

Say a phase has a cap of SEK 300,000. In the week-four report, the forecast shows SEK 340,000. Instead of letting it run, you pause: SEK 20,000 is due to an integration that was trickier than expected, SEK 20,000 to an addition you asked for yourselves. You decide to cut a minor feature to stay within the frame. The invoice lands at SEK 300,000 – not because the estimate was perfect, but because you steered while it was still possible.

Consider a hybrid

You don’t have to choose one purely. A common and sound model is fixed price for what’s well defined and time-and-materials for what’s uncertain – or a fixed budget frame with agile, flexible delivery within it. That gives you predictability where requirements are set and freedom of movement where they’re not.

At Weapp, we’re happy to work on a time-and-materials basis with a clear weekly cost picture, precisely so you keep control without locking the scope in too early. Want to see what the setup could look like? Take a look at our services or get in touch.