Replacing Excel with custom software: when is it time?

Excel is the most underestimated piece of business software in the world, right up until it goes wrong. You replace Excel the moment several people work in the same file every day, you retype data by hand between systems, or there is only one person left who still understands the formulas. Below you will find how to recognise those tipping points, what a spreadsheet error can really cost, and how to make the switch without freezing your operation.

When is Excel due for replacement?

Excel is due for replacement as soon as the file has quietly become your company's operating system: it drives a process, several people depend on it and a mistake has real consequences. One warning sign is no disaster; from three onwards the risks start stacking up. In concrete terms you recognise it by this:

• Several people work in the same file every day and you keep finding versions called planning_v7_FINAL_really.xlsx.
• The same data gets retyped two or three times: from email into Excel, from Excel into the accounts, from the accounts into a report.
• One colleague is the only one who understands the formulas. When that person is on holiday, the process stops.
• You make decisions based on the file (pricing, planning, stock) without anyone still checking the numbers.
• It holds customer data, while the file gets emailed around with no access control and no audit trail. For GDPR that is a problem.

What does a spreadsheet error cost?

More often and more dearly than you would think: errors sit in almost every heavily used spreadsheet, and once such a file drives money or planning, every error registers immediately. Research by professor Raymond Panko, who pulled together dozens of audits of real business spreadsheets, found errors in 94% of the spreadsheets examined, with error rates of 1 to 5% of cells. A few well known examples from the horror stories list kept by EuSpRIG, the European research group on spreadsheet risk, make it tangible:

• JPMorgan (2013). In the risk model behind the "London Whale" affair, an Excel formula divided by the sum instead of the average, which structurally understated the risk. Total trading losses ran to 6.2 billion dollars.
• TransAlta (2003). A copy-and-paste slip in a bidding sheet cost the Canadian energy company 24 million dollars. The CEO called it, literally, "a cut-and-paste error".
• Public Health England (2020). Because of the row limit in the old .XLS format, 15,841 positive covid tests silently dropped out of the reporting, so tens of thousands of contacts were traced too late.

Your SME will obviously lose no billions. Yet a wrong price on a quote, a delivery booked twice or a forgotten order all come from exactly the same source: data with no validation, no structure and no owner.

Why do so many companies still work in Excel?

Because up to a point it simply works: everyone knows it, it costs nothing extra and in one afternoon you build something that does what you need. The FP&A Trends Survey 2024 shows that 52% of organisations still use Excel as their main planning tool.

The real problem sits in what we call the detour tax: the hours your team puts into exporting, retyping, repairing formulas and comparing versions every week. That cost appears on no invoice and you still pay it every month.

Excel or a custom application: which suits your company?

Excel is often simply good enough, and you are welcome to leave it that way. The rule of thumb: if the file stays personal and carries no serious consequences, keep it. If it drives a process that colleagues and other systems depend on, custom software pays off.

Stay with Excel (or a shared spreadsheet) if:

1. One person manages and uses the file.
2. It is about one-off analyses or short lists.
3. An error is annoying at worst and costs nothing serious.

Move to custom software if:

1. The file drives a process: orders, planning, follow-up.
2. Several people have to read and write at the same time.
3. The data has to line up with other systems (accounting, webshop, ERP).
4. You want reports without monthly cutting and pasting.

How do you replace Excel with a custom application?

Step by step, and you start from the process rather than from the screens. Replacing Excel really means revisiting a way of working, so the biggest mistake is building a one-to-one copy of your spreadsheet in app form. This is how we approach such an internal tool:

1. Pick one painful process rather than a whole department. Start where the most time or money leaks away today.
2. Fix one source of truth. Every customer, order or machine exists exactly once, with clear statuses in place of colour codes.
3. Build the workflow first and the dashboard after. Handsome charts on chaotic data are decoration.
4. Let Excel run in parallel during the switch and only turn it off once the team trusts the new tool.

A first working version usually stands within a few weeks with us. Budget-wise, such an internal tool sits close to an MVP: from €8,000, rarely above €25,000, depending on the number of processes and connections.

Is custom software eligible for the kmo-portefeuille?

No, software development itself is not eligible. Since the reform of 1 February 2026, the kmo-portefeuille, the Flemish subsidy scheme for SMEs, only covers training (30% for small and 20% for medium-sized enterprises, capped at €7,500 a year) and cybersecurity advice. IT development projects are explicitly excluded. If you hear something else elsewhere, those are the old rules. What does work: having your team trained in digital or AI skills with subsidy, while you finance the development yourself. Our article on the kmo-portefeuille lists the current rules.

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Not sure whether your spreadsheet is due for replacement? Describe on the contact page how you work with it today (please leave customer data out of it) and we will look together at whether replacing it is worth the effort or Excel is still the right call for now.