From spreadsheet chaos to a single source of truth

When the spreadsheet becomes the risk

A spreadsheet is the correct tool for longer than most people admit. It is flexible, everyone can read it, and it costs nothing. The moment it stops being correct is specific and recognisable: when more than one person needs to write to it at the same time, and when a wrong cell has consequences nobody notices for a week.

At that point the spreadsheet is not a database with poor ergonomics. It is an unaudited system of record with no permissions, no history, and no validation, sitting underneath decisions that increasingly depend on it.

Migrating without a freeze

You do not need to stop work to move. Run the new system in parallel, write to both for two weeks, and reconcile daily. The reconciliation is the point — it surfaces every undocumented rule that lived in someone’s head, and there are always more of those than the team believes.

Only cut over once a full reconciliation cycle passes clean. Then make the spreadsheet read-only rather than deleting it; the archive costs nothing and settles arguments later.