Stop Repeating Yourself in Excel: Turn Your Copilot Instructions into Skills

Same workbook, same reporting steps, same long prompt. At some point you are not really collaborating with Copilot anymore; you are repeatedly explaining your job. Excel skills are an interesting way to change that.

In its 25 June Excel announcement, Microsoft introduced reusable skills alongside personalization and workbook rules. These are related ideas, but I would not treat them as interchangeable.

A skill describes a repeatable task. Personalization expresses your general preferences. Workbook rules keep guidance with a particular file. Start by deciding which problem you are trying to solve.

Check availability before looking for the button

There is an important detail in the announcement: pre-built skills are generally available, while custom skills are initially available through the Windows and Mac Insiders channel. Wider general availability was planned for July, not guaranteed in every tenant on 26 June.

So a missing custom-skills option does not automatically mean IT has configured something incorrectly. Check the supported account, application and release channel first.

My example: a monthly service-request report

Imagine an Excel table called Requests with the columns RequestId, OpenedDate, Team, Category and Status. Every month, you need the number of new requests, the distribution by category, and a list of records that need attention because a required field is missing.

I would make the skill produce a separate report sheet and leave the original table unchanged. I would also ask it to request the reporting period rather than silently deciding what “this month” means.

The following is an illustrative starter SKILL.md:

---
name: monthly-request-summary
description: Prepare a monthly summary from the Requests table without changing the source data.
---

# Monthly request summary

Ask for the reporting month and year before making changes.
Inspect the Requests table and confirm its required columns exist.
Stop and explain any missing columns; do not invent replacements.

Create a separate report worksheet.
Count requests opened in the chosen period, grouped by category and team.
List records with missing RequestId, OpenedDate, Category or Status.
Do not infer a missing category or status from other fields.

Preserve the original table and existing formulas.
State the date boundaries, filters and assumptions used.
Explain how the grouped totals reconcile to the included source rows.
Return a short review checklist with the result.

Test the awkward rows, not only the clean ones

For a first test, I would create a disposable workbook containing a request just before the month starts, one exactly on the first day, one on the final day and one in the next month. Add a duplicate request ID, an empty category and an invalid date.

Write down the expected counts yourself. Does the result include the correct period? Does it flag the incomplete records without quietly repairing them? Do the grouped totals reconcile? Inspect the source table afterwards to confirm that it was not changed.

Repeat the same test after editing the skill. Version the instructions you approve, and give one person ownership of future changes.

Final thoughts

This is a useful next step after an Excel prompt cheatsheet. The goal is not to create the longest possible skill. It is to capture one repeatable task clearly enough that its output is easier to check.