How to Use Copilot Skills in Excel

This is part of the Microsoft 365 Copilot Skills series. Start with the hub if you need the difference between a Skill, prompt, plugin, connector, and agent.

Copilot Skills in Excel let you save a repeatable workbook method and call it again with an @ mention. Microsoft also has a developer preview that lets a packaged Skill run Office.js code inside Excel.

The names are almost identical. The status is not:

Official UI reference: Microsoft Support — Copilot in Excel Skills.

The short version

• Open Copilot in Excel.
• Select Add work content.
• Select All Skills.
• Pick a Skill, or invoke one directly with @skill-name.
• Use Settings > Manage skills to control automatic Skill selection.
• Create personal custom Skills in the OneDrive Skills folder.
• Put each Skill in its own folder with a matching SKILL.md.
• Microsoft-managed Skills include @brandkit and @theme-design.
• Keep the Office.js path clearly labelled Preview.
• Do not use Office.js custom Skills in production yet.

Find and use Skills in Excel

The end-user flow starts from the Copilot prompt box:

1. Open the workbook you want to work on.
2. Open Copilot in Excel.
3. Select the Add work content menu in the prompt field.
4. Select All Skills.
5. Choose the Skill you want.
6. Add any workbook-specific detail and send the request.

The All Skills list can include:

• Skills provided by Copilot in Excel; and
• personal custom Skills from your OneDrive Skills folder.

Official UI reference: Microsoft Support — use Skills in Excel.

Invoke a Skill with an @mention

You can skip the picker and call a Skill directly:

@theme-design

Apply an Excel theme across this workbook.
Keep the existing formulas, values, sheet names, and table structure.

Microsoft’s public examples also use names such as:

• @brandkit
• @portfolio-monitoring
• @variance-analysis
• @model-update
• @comps-analysis

Availability differs. brandkit and theme-design are Microsoft-managed Skills. Finance examples can come from sample, custom, or future partner Skills, so do not promise that every tenant has every name.

Manage Skills

To control which Skills Copilot can select automatically:

1. Open the Settings menu in the upper-right corner of the Copilot pane.
2. Select Manage skills.
3. Open the relevant folder.
4. Turn Skills on or off.

Official UI reference: Microsoft Support — manage Excel Skills.

Excel has one useful difference to remember:

Turning a Skill off stops Copilot from selecting it automatically, but you can still invoke the disabled Skill directly with its @ mention.

That gives you two levels of control:

• enabled — Copilot can choose it when relevant;
• disabled — it stays out of automatic selection, but you can still call it explicitly.

Microsoft-managed Excel Skills

Microsoft publicly documents many built-in Skills and names two Microsoft-managed formatting Skills.

brandkit

Use @brandkit to apply organisation-approved brand guidance across a workbook.

It can style:

• colour palettes;
• typography;
• chart and table appearance;
• headers;
• logos, when an official Brand Kit is available.

The Skill is enabled by default and appears in the Formatting folder in Manage skills.

Things to know

@brandkit can reference a Brand Kit created by your organisation’s brand manager. Check what Brand Kit your organisation has configured before expecting a branded result.

theme-design

Use @theme-design to apply an Excel theme using design guidance from the Excel team.

It can work across:

• charts;
• tables;
• cells;
• borders;
• colour hierarchy;
• colour contrast.

The Skill is automatically enabled and also appears under Formatting.

Official source: Microsoft Support — Microsoft-managed Skills in Excel.

Create a personal custom Skill

The Excel support page documents a OneDrive-backed flow:

1. In Copilot, open Settings.
2. Select Manage skills.
3. Select Custom skills.
4. Select Create OneDrive folder.
5. Select Open skills folder.
6. Add one folder per Skill.
7. Put SKILL.md inside the folder.
8. Return to Excel and select Refresh.

Official UI reference: Microsoft Support — create custom Excel Skills.

The folder name and the name field must match:

format-variance-table/
└── SKILL.md

---
name: format-variance-table
description: >
  Formats an existing variance table in Excel. Use when the user asks
  to highlight favourable and unfavourable variances or prepare a
  variance table for review.
---

# Format a variance table

1. Use the existing table and labels.
2. Preserve formulas and source values.
3. Apply one consistent number format.
4. Make favourable and unfavourable variances easy to distinguish.
5. Do not invent a target, owner, or explanation that is not in the workbook.

This is an instruction-only Skill. It uses the capabilities Copilot in Excel already has.

Availability

Microsoft’s 25 June 2026 Excel announcement gives the clearest public status split:

The current Excel support page documents personal custom Skills without a preview banner.

Confirm that custom Skills are present on Excel for web, Windows, and Mac in your tenant. The public Skills sources do not confirm iPad support or provide a Skills-specific SKU table.

The separate Office.js developer preview

Now the second story.

Microsoft also lets developers create a packaged Excel Skill with JavaScript in a scripts/ folder. That script can use Office.js to read or change the workbook.

Microsoft’s warning is direct:

Custom Skills for Excel are in preview. Do not use them in a production Skill.

The developer path is for testing and learning today.

What the package contains

A preview package can look like this:

excel-skill-package/
├── manifest.json
├── color.png
├── outline.png
└── skills/
    └── find-accelerating-growth/
        ├── SKILL.md
        ├── resources/
        │   ├── workbook-data-guardrails.md
        │   └── excel-vs-agent-execution.md
        └── scripts/
            └── find-accelerating-growth.js

Excel-specific SKILL.md guidance

Microsoft’s developer overview recommends:

1. Add excel to metadata.tags.
2. Use a Workbook output section instead of a generic output section.
3. Add a Common pitfalls to avoid section.
4. Explain when the Skill should run inside Excel.
5. Explain what to do when the Skill is invoked outside Excel.
6. Point to the exact script by its relative path.

---
name: find-accelerating-growth
description: >
  Finds rows in an Excel table whose values rise with increasingly
  larger increases. Use when the user asks for accelerating growth.
metadata:
  version: 1.0.0
  tags: excel, office-js, tables, trends
---

Office.js script rules

The preview guidance says:

• put JavaScript files in scripts/;
• make each script run to completion without more user or agent input;
• typically use one asynchronous Excel.run(...) block;
• do not call Office.onReady;
• do not define Office.initialize;
• let Copilot create and initialise the Office.js runtime.

await Excel.run(async (context) => {
  const worksheet = context.workbook.worksheets.getActiveWorksheet()
  worksheet.load('name')
  await context.sync()

  return `Active worksheet: ${worksheet.name}`
})

The preview does not support passing parameters into the functions that call Office.js. The workbook itself supplies the input.

Manifest and runtime caveats

Microsoft says the Skill does not need an "extensions" section merely to start Office.js. Copilot in Excel creates the runtime and executes the packaged script.

That also means there is no "extensions.requirements.capabilities" key to restrict the Skill to an Excel requirement set. Microsoft says the effect of calling an unsupported API is undefined.

If the same package also contains an Office Add-in or Teams app, the Skill cannot share its packaged Office.js file directly with the hosted app. You must duplicate code that both surfaces need.

The current Excel tutorial and Cowork packaging examples show different manifest versions. Use the latest schema required by the live validator rather than copying a version number from this post.

Test the developer preview safely

The public tutorial uses Microsoft 365 Agents Toolkit to package and install the app.

The test loop is:

1. Build the package.
2. Install it for your test account.
3. Open the workbook in Excel.
4. Wait for the Skill to appear.
5. Invoke the full @skill-name.
6. Check the workbook output and Copilot response.
7. Remove the app after the test session.

Microsoft’s uninstall steps use Teams:

1. Open Apps.
2. Select Manage your apps.
3. Find the package.
4. Select the trash icon.
5. Select Remove.

What makes a good Excel Skill?

The best Excel Skills make the workbook result easy to inspect.

Useful guardrails include:

• use the workbook as the source of truth;
• name the sheets, tables, or ranges the Skill may inspect;
• preserve formulas unless the workflow explicitly changes them;
• never invent missing values;
• stop broad searches when the required data is found;
• state what the Skill completed and what still needs user action;
• never claim a workbook update succeeded outside an Excel-capable environment.

Troubleshooting

Admin note

The public Excel Skills page explains the user and OneDrive flow. It does not name the tenant control for enabling or blocking personal Skill uploads, or describe a complete audit/DLP model for that personal path.

Keep these as open checks:

1. the exact admin policy controlling personal Excel Skills;
2. the eDiscovery and retention treatment of the OneDrive Skills folder;
3. partner Skill deployment when marketplace support reaches the tenant;
4. the Office.js preview’s exact channel and tenant requirements.

Continue the Copilot Skills series

• Microsoft 365 Copilot Skills, explained — the hub.
• Skills in PowerPoint — Choose skills, @ mention, upload, and management.
• Skills in Word — what Word has today and what it does not publicly document.
• Cowork Skill packaging and distribution — packages, connectors, MCP, validation, and publishing.
• Write your first SKILL.md — the practical authoring guide.
• Admin and governance for Copilot Skills — controls, permissions, Purview, and rollout.

Official public sources

• Microsoft Support — use and manage Copilot Skills in Excel
• Microsoft Support — Microsoft-managed Skills in Excel
• Microsoft 365 Blog — Copilot in Excel for finance
• Microsoft Learn — overview of Office.js Copilot Skills for Excel
• Microsoft Learn — Office.js Copilot Skill tutorial
• Agent Skills specification