Excel is a fine place to start a competency matrix, and most organizations do. The problem is not that Excel is bad — it is that in four specific places it quietly produces wrong information.
Building a competency matrix in Excel is not wrong. It is fast, everyone knows it, there is no licence to buy. Most organizations start there and it works fine for a while.
The problem is the four places where Excel quietly produces wrong information. None of them raise an error; the table always looks correct. And all four surface at the same moment: audit day, or while planning a critical shift.
Excel is a photograph: correct on the day you fill it in. Competence is data that expires. The four break points all come from that mismatch: expiry tracking, evidence, change history and a single source of truth.
Most competencies have a shelf life: certificate validity, refresher intervals, operator licences. When you mark someone "competent" in Excel, that mark does not drop by itself. Even with an expiry column, somebody has to read it and act.
So the table is right the day it is filled in and partly invalid six months later — while still showing green. The person planning shifts looks at that green. So does the auditor, who then asks for the date.
Conditional formatting helps to a point: it turns the cell red. But it notifies nobody, assigns nothing, and if no one opens the file, nothing happens.
You type "3" in a cell. Six months later, "what was that 3 based on?" has no answer. Maybe an exam, maybe a foreman's observation, maybe an external certificate. Only the number survives.
This is the critical gap in an audit. The question is not "do you have a matrix" but "how do you know this person is competent" — and a number does not answer it.
Someone's score went from 2 to 4. Who changed it? When? On what basis? Excel does not hold this. Even with change tracking on, nobody reads those records months later.
It bites in two places: ISO expects a record's origin to be traceable, and internally the "I did not give that score" argument cannot be settled without a log.
The best-known and most underestimated problem: the file multiplies. It gets emailed, downloaded, edited in someone's own copy, and three months later there are two different "current" files.
A shared cloud file reduces this but does not eliminate it: simultaneous edits, an accidentally deleted row, a saved filter, a shifted column — all still possible, none reversible.
There is no headcount threshold, but there is a symptom list. If two of these three apply, you have reached Excel's limit:
If none apply, staying in Excel is entirely reasonable. Changing tools does not improve anything by itself; the real gain is in the method (start from the job, define the scale, require evidence). You can apply the same method in Excel — you just carry expiry, evidence, history and single-source duties manually.
Excel is a photograph; competence is data that expires. All four break points come from that mismatch. If expiry tracking and audit evidence apply to you, you have reached the limit; if not, there is no hurry.