Copilot in Excel custom skills not showing? Check that Office is in English first

What is a custom skill in Copilot in Excel?

I will explain some background first. A skill is a set of written instructions that Copilot reads before it does a task. You can think of it like a recipe card you leave for a new colleague. Instead of explaining every Monday how the report should look, you write it down once, and Copilot follows the same steps each time you ask for that report.

A custom skill is one you write yourself. Microsoft’s page, Use skills with Copilot in Excel to complete repeatable tasks, says custom skills are saved in a specific folder in your OneDrive. You make one folder per skill, and each folder holds a file called SKILL.md. The top of that file is the frontmatter. This is a short block between two lines of three dashes that holds a name and a description. Everything under it is your instructions in plain words, and they have no fixed format.

The file follows the open Agent Skills format, and this is the same format Claude skills use. I already keep my own repeatable jobs as written instructions for an AI. I described this in how I trained Claude to write like me, so the idea will feel familiar if you have done anything like that.

You also need the right licence. Computerworld’s report on the June 2026 announcement says the skills features are for paid Microsoft 365 Copilot users. They also note that custom skills started in the Insider channel before the general release the month after.

Why does the Office display language stop skills from showing?

Office has more than one language setting, and this is where the confusion starts. The display language is the language of the buttons, menus and tabs. The editing or proofing language is the one used for spell check in what you type. You can type English into a workbook every day while your menus are in French, and Copilot can still answer you in English. This is why it feels like everything is in English.

Microsoft’s skills page has a note at the very top. It says skills with Copilot in Excel are only supported in English, and your Microsoft Office display language must be set to English to access skills. It links to Microsoft’s page on changing the language Office uses in its menus and proofing tools, and this is where you change it.

I will give you an example. An analyst in Lahore uses Excel with English menus, and the skills menu appears for them. Their colleague in Berlin has the same licence and the same SKILL.md file in OneDrive. But Office shows its menus in German for the colleague, so the skills never appear. Nothing is wrong with the file, and the only difference is a setting that most people never open.

On Windows you find the setting in File, Options, Language, under Office display language. You select English, choose Set as Preferred, and close and reopen your Office apps so it takes effect. Keep in mind that this changes the menus in Word, PowerPoint and Outlook too, and not only in Excel.

Where should the skills folder be in OneDrive?

I recommend you let Copilot make the folder for you, and do not build it by hand. Microsoft’s page says custom skills live in a specific folder in OneDrive, but it does not print the path. It gives you buttons instead. The buttons are the safe route because Copilot creates the folder exactly where it will look later.

1. 01
   Open the Copilot settings

   In the Copilot pane in Excel, select the Settings menu, the three dots in the upper-right corner.
2. 02
   Go to Custom skills

   Select Manage plugins & skills, then Custom skills.
3. 03
   Let Copilot create the folder

   Select Create OneDrive folder. Copilot creates the skills folder in your OneDrive.
4. 04
   Open it from the same dialog

   Select Open skills folder. Put one folder per skill in here, each with its own SKILL.md.

This matters because Microsoft now has skills in more than one Copilot app. Guides written for one app can show a folder path that belongs to another. If you copied a path from a guide and made the folders yourself, start again with Create OneDrive folder. Then you move your skill folders into the one Copilot opens.

Why does Copilot skip my skill folder?

A mismatched name is the cause most people find on their own, and it is easy to get wrong without noticing. Microsoft’s page says Copilot skips any folder whose name does not match its name in SKILL.md. So a folder called Weekly Sales Report, with name: weekly-sales-report inside the file, is skipped. Copilot gives you no message about it.

The name itself also has rules. Microsoft says custom skills must follow the industry standard format to be recognised. The Agent Skills specification says a name can be up to 64 characters. It uses only lowercase letters, numbers and hyphens, and it does not start or end with a hyphen. It does not have two hyphens in a row, and it must match the folder it sits in. So the safe habit is to write the name in lowercase with hyphens, and then copy that exact text as the folder name.

That last row in the table is an easy trap. If you copy a skill folder in File Explorer to keep a backup, Windows names the copy weekly-sales-report - Copy. If you then open and edit the file in the copy, Copilot keeps using the old version and ignores your changes. You should look at the folder names in OneDrive itself, and not only at the file you have open.

There is a second part people miss. Microsoft’s page says that if you add or rename a custom skill in OneDrive, you select Refresh in the Custom skills dialog so Copilot recognises the change. So after every fix, you go back to Settings, Manage plugins & skills, Custom skills and press Refresh before you test again. The description line is not decoration. It tells Copilot when to use the skill, so write it as the request you would actually type, like “Use when I ask for the weekly sales report”.

Why does a skill I turned off still run?

You can turn each skill on or off in Settings, Manage plugins & skills. Most people expect off to mean off. But Microsoft’s page marks this as important. Turning a skill off stops Copilot from using it automatically, but you can still use a disabled skill with a direct @mention in your prompt.

In practice that is useful, but it is also a risk. It is useful because you can keep a rarely used skill switched off so Copilot does not pick it by mistake. You can still call it by name when you need it. It is a risk on a shared team, because switching off an old version of a report skill does not stop someone from typing its name and getting the old layout. If a skill is wrong, fix it or rename its folder, and do not rely on the switch.

Do custom skills need the Insider build or version 2608?

You may read that skills need Excel version 2608 on the Beta or Current Channel (Preview). That is true, but it is for a different kind of skill. Microsoft’s developer page, Overview of Copilot skills for Excel (preview), is about skills that run Office.js scripts. This is JavaScript code that changes the workbook directly, and it is packed into an app and installed through Teams.

The SKILL.md you drop into your OneDrive skills folder is the personal route described on the support page. That page names no version or channel at all. So if your custom skill is missing, check the language and the folder name before you move your Excel to a preview channel.

What should you check first when a custom skill is not showing?

I suggest you go from the cause that blocks everything to the one that blocks a single skill. If the built-in skills like @brandkit and @theme-design do not appear either, the problem is the licence or the language. If those appear and only yours is missing, the problem is the folder or the name.

Once the skill shows, test it on a copy of the workbook first. A skill that builds a report will build it the same way every time, and this includes any mistake in your instructions. So check its first output the way I check any number an AI gives me in Excel. If the skill shows but Copilot will not change the sheet, that is a different problem, and my guide to Copilot in Excel not editing covers the Manual calculation trap behind it. If the job is a report that runs every week no matter who is at the desk, automating the Excel report itself may still be the more reliable route.