When only one person understands the spreadsheet.
The spreadsheet may be doing its job perfectly well. The risk is that the business can only use it because one person knows the rules, checks and exceptions behind it.
You probably know the spreadsheet. Someone smart built it to solve a real problem, and the business grew around it.
The spreadsheet is not automatically the problem.
The systems in the business could not handle a particular calculation, schedule, report or approval, so a capable person built something that could.
It worked. Other people started using it. More information was added. Over time, it became part of how the business runs.
That does not make the spreadsheet bad. A well-built spreadsheet can remain the right tool for years. Replacing it simply because it is a spreadsheet can waste time, money and the knowledge already built into it.
The problem starts when only one person understands what happens inside it.
They know which information to enter, which result looks wrong, which rule has an exception and what to do when the numbers do not match. If they are away, everyone else waits, guesses or avoids touching it.
At that point, the business does not really own the job. The person does.
Find the job hidden inside the file.
Do not begin by asking how to replace the spreadsheet.
Start with a smaller question: what job does the business rely on this spreadsheet to complete?
It might produce a price, schedule a team, calculate stock, prepare a client report or decide what needs approval. Name that outcome clearly.
Then ask what sets the work in motion. What information goes in? What does the person check? Which decisions follow a rule? Which decisions need their judgement? What tells them the work is complete?
These questions matter more than the number of tabs or formulas. They reveal the operating knowledge that the spreadsheet alone cannot show.
You may discover that the file is fine and the process around it needs work. You may also find that one fragile part should move into another system. Either result is useful because it is based on the real job, not an assumption about the tool.
Make the business the owner.
Keep important judgement with a person. The aim is not to automate every decision. It is to stop routine work from waiting unnecessarily while making clear when human experience is still required.
A good result is not a newer spreadsheet or a larger system. It is another capable person completing the routine, the right person handling genuine exceptions and the business being able to see how the job works.
The original expert still matters. Their knowledge is being used properly instead of being trapped in a task only they can perform.