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Choosing a partner

What a software build actually costs, beyond the quote

Comparing two quotes compares one line of the real cost. The rest is spread across verification, the changes you will inevitably make, the handover, the maintenance, and your own team's time, and it is the part that makes a cheap quote expensive. This is a model for putting numbers against those lines, so two proposals can be compared on something closer to the truth.

  • The quote is often the smaller half of the total.
  • Cost of change is the largest cost on anything that lives longer than a year.
  • Your own team's time is a real line and is almost never counted.
  • A cheaper quote with weaker verification usually costs more by year two.

Take both proposals and fill in every line below. The quote is line one of seven.

1. The quote

What they said it costs. Note whether it is fixed or an estimate, and what happens if it is wrong.

2. Verification

Is the cost of automated checks inside the quote or extra? If a supplier's number is materially lower than another's, this is the first place to look, because checks are the easiest thing to leave out and the hardest to notice missing.

A quote without verification is a quote for something different, not a better price for the same thing.

3. The changes you will make

Nobody builds exactly what they first described. Estimate three or four changes of moderate size in the first year and ask each supplier what those cost.

This line is the largest part of the total on anything that lives more than a year, and it varies enormously by supplier and contract type.

4. Your own team's time

Almost never counted, and often substantial. Somebody on your side writes or reviews requirements, answers questions, tests, and coordinates. On an ambiguous scope across time zones this can run to a meaningful share of a full-time role.

Distributed delivery lowers the supplier's hourly cost and raises this line, which is exactly why the comparison is not just about rates.

5. Handover and onboarding

What does it cost your team to take it over? If there is no specification and no runnable check suite, the answer is weeks of reading code, and that is a real cost even though no invoice arrives for it.

6. Maintenance and incidents

Who fixes it, how quickly, and at what price? A defect reaching a customer costs support time, credibility, and engineering time, and the frequency of that depends directly on line two.

7. The cost of being wrong

The one nobody models, and the reason verification is worth paying for at all. What does one serious defect cost you: a security incident, a payment error, a data exposure? Multiply that by how likely it is under each supplier's approach.

If the answer is small, buy the cheaper quote without worry. If it is large, a cheaper quote with weaker verification is a worse deal at any price.

Using the model

Fill it in with ranges rather than single numbers. The goal is not a precise total, which is unobtainable. It is to see which supplier's quote is low because they are efficient and which is low because something is missing.

Where we fit

Reveneau suits this when

  • You are comparing two quotes that differ substantially and cannot tell why
  • You need to justify a supplier choice that is not the cheapest

Common questions

Why are two quotes for the same software so different?
Usually because they are not for the same thing. The most common differences are whether automated verification is included, how changes are priced, and how much of the coordination and testing work falls to your team. Check verification first; it is the easiest thing to omit and the hardest to notice.
What is the biggest hidden cost in a software build?
The biggest hidden cost in a software build is usually the changes made after the first version is released, on anything that lives more than a year. Nobody builds exactly what they first described, and the price of a mid-build change varies enormously by supplier and contract type. This single line is a larger part of the total cost of a build than the original quote is.
Should I count my own team's time?
Yes, and almost nobody does. Someone writes or reviews requirements, answers questions, tests, and coordinates. On an ambiguous scope across time zones this can consume a meaningful share of a full-time role, and it is precisely the line that a lower hourly rate tends to increase.
Is the cheapest quote ever the right answer?
Yes, when the cost of being wrong is genuinely low. For an internal tool where a defect means someone re-enters a form, buy the cheap quote. When a defect means a security incident or a payment error, a cheaper quote with weaker verification is a worse deal at any price.
Is verification included in a software quote?
Verification, meaning the cost of automated checks, is the first thing to check when one software quote is materially lower than another. It is the easiest line for a supplier to leave out and the hardest for a client to notice missing, because a quote without verification is priced for something different, not for a cheaper version of the same build. Ask each supplier to state it as a separate line.
What does handover and onboarding cost after a software build?
Handover and onboarding costs whatever it takes your team to take the software over once the supplier is gone. If there is no specification and no runnable check suite, that cost is weeks of a developer reading unfamiliar code, and it is a real cost even though no invoice ever arrives for it. Comparing two proposals without this line understates the total cost of the cheaper one.
What is the cost of being wrong in a software build?
The cost of being wrong is what one serious defect costs after release: a security incident, a payment error, or a data exposure, multiplied by how likely that defect is under a given supplier's approach. It is the line nobody models on their own, and it is the entire reason paying for verification is worth it. A small cost of being wrong makes the cheaper quote the right choice.
How many cost lines are in the total cost of a software build?
The total cost of a software build has seven lines: the quote itself, verification, the changes made after the first version, your own team's time, handover and onboarding, ongoing maintenance and incidents, and the cost of being wrong. Comparing two proposals on the quote alone compares one line out of seven, and it is usually the smaller half of what the build actually costs.
How should I use the total cost of a build model?
Fill in the seven-line model with ranges rather than exact figures for each proposal you are comparing. The goal is to see which supplier's quote is low because they work efficiently and which is low because a real cost, like verification or your own team's time, has been left out. A precise total is rarely achievable, so treat the ranges as a comparison tool, not a forecast.