Rules, personalization and skills: getting Copilot in Excel to do month-end work the same way every time

How personalization, a .Rules sheet and skills differ

All three save you retyping the same instructions. They are stored in different places, so each reaches different people.

Personalization for the formats you use in every file

1. Open the Copilot pane and select the Settings menu (the ... at the top right of the pane).
2. Select Personalization.
3. Type your preferences. You can add several.
4. Select Save. They apply from your next prompt.

Microsoft suggests keeping each preference short and specific. For someone who builds financial reports, these fit almost every file:

• Show amounts in baht with thousands separators and no decimals
• Show negative numbers in brackets
• Use dd/mm/yyyy dates
• Give a summary of no more than three lines before any detailed table
• Use column charts for month-by-month comparisons

Personalization is stored on your account, not in the file, so a colleague who opens the workbook after you does not get it. If the whole team needs the same format, put it in the workbook's .Rules sheet instead.

When a prompt asks for something different, Copilot follows the prompt. If a result ignores a preference, Microsoft suggests repeating it in that prompt or rewording the saved preference. To stop using personalization, clear the text in the Personalization dialog and select Save.

The .Rules sheet: rules that travel with the workbook

Rules are instructions for one workbook, kept on a sheet named .Rules (with the leading dot). When you prompt Copilot in that file, its results follow the rules. When you send the file to someone, the rules go with it and they need no setup.

There are four ways to create a .Rules sheet:

• In the Copilot pane, open the Add menu in the prompt box and select Create workbook rules. Excel adds a .Rules sheet with a template of suggested rules.
• Add a sheet yourself, name it .Rules and type the rules.
• Copy a .Rules sheet from another workbook.
• Ask Copilot, for example "Create a .Rules worksheet based on the formatting already used in this workbook."

Microsoft's conditions: rules go in column A, the sheet must be named .Rules, and it must be visible. Copilot does not read a hidden .Rules sheet.

Put one rule in each cell and group them under heading cells that start with ##. Microsoft recommends short examples, since showing the result works better than describing it. Example rules for a monthly actual versus budget workbook:

## NUMBERS
Show amounts in baht with thousands separators and no decimals
Show negatives in brackets, e.g. (12,500)
Variance = Actual − Budget; show variances that reduce profit in red
## DATA
Actuals are in table tblActual, budget is in table tblBudget
Summary sheets use formulas that reference the tables; never type over them
Do not edit the Budget sheet
## CHARTS
Month-by-month comparisons use column charts, never pie charts

A rule can be a formula. Put =IF(COUNTA(Actual!A:A)>1,"Compare forecast to actuals","Build forecast only") in A12. Before month end the Actual sheet is empty and Copilot builds the forecast only. Once actuals are in, the same rule switches to comparing against them. Copilot reads the formula's result on the next prompt.

Because the .Rules sheet has to stay visible, anyone who receives the file can read every rule. Before you send the workbook to a customer, an auditor or anyone outside the company, check that the rules contain no customer names, internal thresholds or anything else that should stay inside.

If each month's report starts as a copy of a template, put the .Rules sheet in the template. Every month's file then carries the same rules.

Skills: saving the steps of repeatable work

A skill is a set of instructions for repeatable work. Microsoft supplies some and you can write your own. In the Copilot pane, open the Add menu in the prompt box and select Choose plugins and skills, or type the skill's name with @ in a prompt, such as @clean-data.

To turn skills on or off, go to the Settings menu (the ...) > Manage plugins & skills. Copilot will not pick a skill that is off by itself, but you can still call it with @.

Microsoft also lists a set of finance skills, mostly for investment banking and private equity, such as lbo-model, merger-model and comps-analysis. The two that suit an ordinary company's finance team are check-model, which looks for circular references, broken formulas, hard-coded overrides and a balance sheet that does not tie to cash flow, and model-update, which rolls a forecast forward with new results or assumptions. Microsoft's page does not say how to call these or whether they have reached every account.

Check what check-model reports the same way you would test Copilot with questions you already know the answer to: against a figure you trust.

Writing your own skill as a SKILL.md file

Microsoft's advice is to make a skill once you notice you keep asking Copilot for the same thing. There are two ways. The first is to type @skill-builder and have it build one from your instructions, earlier prompts, finished examples or the work you just did. You can preview and refine it before Copilot saves it to OneDrive. (skill-builder is still rolling out, so some accounts will not see it yet.)

The second is to write the file yourself:

1. In the Copilot pane, select the Settings menu (the ...) > Manage plugins & skills > Custom skills.
2. Select Create OneDrive folder. Copilot creates a skills folder in your OneDrive.
3. Select Open skills folder.
4. Add one subfolder per skill, named exactly like the skill's name, with a SKILL.md file inside.

SKILL.md has two parts. The header between the --- lines must have a name and a description, and the description is what tells Copilot when to use the skill. Below it go the steps, in any format you like. A skill for the monthly variance summary:

---
name: month-end-variance
description: Use when the user asks for actual versus budget for a given month.
---
1. Read actuals from table tblActual and budget from table tblBudget for the month the user names only.
2. Add a sheet named Variance_YYYY-MM with columns Account, Actual, Budget, Variance, Variance %.
3. Every number on the new sheet is a formula that references the tables. Never type values in.
4. Use red text on lines where the variance cuts profit by more than 10%.
5. Write a summary of five lines at most, starting with the line that moves profit most.
6. In the last row, compare total actuals with the total on the P&L sheet. If they differ, tell the user before going further.

Step 6 belongs in every skill a finance team writes. Copilot can read the wrong month or the wrong version of the data, and a total that does not tie to the P&L is the first sign of it.

After adding or renaming a skill in OneDrive, select Refresh in the Custom skills dialog. To stop using a skill without deleting it, rename its folder so it no longer matches the name in the file, and Copilot skips it.

A skill can also hold scripts, references and assets folders. Microsoft's FAQ says scripts in a skill do not let Copilot do anything beyond the tools it already has.

Turning off Copilot's formula suggestions

Copilot suggests formulas in two ways. When you type = in a cell, it proposes a complete formula from the headers and tables around it, with a preview of the result. When you type a few example values that follow a pattern, it proposes one formula to fill the rest of the column. Each can be turned off on its own.

• Excel for Windows: File > Options > Copilot, clear Show Copilot suggestions for completing formulas or Show Copilot suggestions for formulas based on patterns in your content, then select OK.
• Excel for the web: File > Options (...) > Copilot Settings and clear the box you want, or select More options (...) on a suggestion card and choose Turn off Copilot suggestions for completing formulas.

The setting stays until you turn it back on. It is not a one-time dismissal.

What to set up first

1. Personalization: a few minutes, affects only you. Start with number and date formats.
2. A .Rules sheet in the report template: everyone who opens the file gets the same rules, including next month's copy.
3. A skill: write it once the steps have settled and you have given the same instructions for several months. Test it on a closed month whose totals you know before using it on a live month.

For the plans that include Copilot and how its modes work, see Copilot in Excel for financial reporting.

Questions about Copilot in Excel rules and skills

Sources

Checked against Microsoft's support pages on 27 October 2026. Microsoft notes that Copilot in Excel and its models change quickly, so rules and skills may behave differently across models and over time, and menu names may move. Check Microsoft's current pages before setting up a live file.

• Microsoft Support: Personalize Copilot in Excel
• Microsoft Support: Create workbook guidelines with Copilot in Excel rules
• Microsoft Support: Use skills with Copilot in Excel to complete repeatable tasks
• Microsoft Support: Built-in skills in Copilot in Excel
• Microsoft Support: Turn Copilot formula suggestions on or off
• Microsoft Support: Frequently asked questions about Copilot in Excel

Read next

• ArticleCopilot in Excel: bringing in data from other workbooks, Power BI and the web, and finding who changed a cell
• ArticleCopilot in Microsoft Excel for financial reporting: what it does, what it needs, what to check
• ArticleTesting Copilot in Excel on a sample P&L: questions with known answers
• ArticleReading a budget variance: favourable, unfavourable, and what to check next
• ArticleWhat a monthly management report should contain, and in what order
• DownloadDownload 01 Executive Review