Two Excel entries on Microsoft's public Microsoft 365 roadmap now carry the status Launched. Plan Mode for Copilot in Excel (roadmap 560338) lists a general availability month of May 2026, with the entry updated on 7 October 2026. The Excel Agent (roadmap 543422) lists March 2026 and was updated on 29 September 2026. Around them, the Microsoft 365 Copilot release notes dated 23 September 2026 added two Excel changes that matter more than they sound: the Copilot chat response now links straight to the sheets, tables, ranges and charts it changed, and the Show Changes pane attributes edits to Copilot. The 25 August notes added Python execution to Edit with Copilot. And since 14 September the =COPILOT() worksheet function has been retired.
Neither Plan Mode nor the Excel Agent appears in the September or August release notes under Excel; both are tracked on the roadmap only. That is worth saying plainly, because it is why finance teams keep asking Frontrow which of the three things called 'Copilot in Excel' they actually have. This note separates them, walks through what each does using Microsoft's own steps, and sets out what an Australian business should do with them this month.
Three things called Copilot in Excel
| Surface | Where it lives | Status and date | Licence, as published |
|---|---|---|---|
| Plan Mode for Copilot in Excel | Copilot pane inside Excel on Windows, Mac and web, on the open workbook | Roadmap 560338: Launched, GA May 2026, updated 7 October 2026 | Not restated on the entry. Part of Copilot in Excel, the in-app experience of the Microsoft 365 Copilot add-on |
| Excel Agent | Microsoft 365 Copilot chat; output opens in Excel | Roadmap 543422: Launched, GA March 2026, updated 29 September 2026 | Microsoft 365 users with or without a Microsoft 365 Copilot licence |
| Edit with Copilot running Python | Copilot in Excel on Windows, Mac and web | Release notes, 25 August 2026 | Part of Copilot in Excel; existing Python security and execution controls apply |
| =COPILOT() worksheet function | A formula in a cell | Retired 14 September 2026; preview only, never generally available | Gone |
In short: Plan Mode is how Copilot in Excel now handles a multi-step change to a workbook you already have open. The Excel Agent is a chat-based agent that builds a workbook, chart or summary from data and hands it to Excel. COPILOT() was a formula that asked a language model for a cell value, and Microsoft removed it. Frontrow's checklist for anyone still carrying that function is at /insights/excel-copilot-function-retiring-september-2026.
What Plan Mode does
Microsoft's roadmap description is specific. Before Copilot changes anything in the workbook, it outlines a step-by-step approach. The user reviews how Copilot intends to complete the task, sees which data or capabilities may be used, and can adjust the plan. Only then are the edits applied. The stated purpose is to make multi-step or high-impact tasks tractable while the user stays in control of every change. The September release notes close the loop on the other side: once Copilot has modified the workbook, the chat response shows the changes in a distinct format with highlighted links to each new sheet, table, range or chart, and under Review, Show Changes, attribution cards now mark which edits Copilot made. A Plan Mode task therefore has a readable plan before, a navigable list of changes during, and an audit trail after.
- 1Open the workbook, open the Copilot pane, and describe a task that needs several steps, for example a summary sheet, a derived column and a chart.
- 2Review the plan Copilot proposes: the steps, the data it will use and the capabilities it will call on. Remove or reword anything you do not want. (Roadmap 560338.)
- 3Approve the plan and let Copilot apply the edits.
- 4In the chat response, use the highlighted links to jump to each new sheet, table, range or chart and check it. (Release notes, 23 September 2026.)
- 5Select the Review tab, then Show Changes, and look for the Copilot attribution cards to confirm what the AI touched versus what a person did. (Release notes, 23 September 2026.)
What the Excel Agent does
The Excel Agent is a different animal. Per its roadmap entry it turns data into charts, summaries and insights using built-in formulas and logic, covers data preparation, formulas and visualisation, and supports multi-turn chat so the user refines the output before opening it in Excel for full editing and collaboration. Microsoft names financial forecasts, project plans and decision-making tools as the intended uses. The line that matters commercially is the last one: it is available to Microsoft 365 users with or without a Microsoft 365 Copilot licence. One related item: federated Copilot connectors (roadmap 501120, generally available) fetch third-party data in real time over the Model Context Protocol without storing or indexing it in Microsoft services, under the user's identity and admin centre governance. The roadmap lists Agent Mode in Excel among the supported surfaces; the 23 September release note says 'when editing with Copilot in Excel'.
A worked example
Take an operations manager at a regional civil contractor who keeps a plant-hire workbook: about 400 hire transactions a month across 30 machines, each with machine ID, supplier, days hired and cost. The board pack needs cost per machine per month, a flag on any machine whose hire cost rose more than 20 per cent on the prior month, and the top 10 by spend. With Plan Mode, one prompt for all of that comes back as a plan: a PivotTable on a new sheet by machine and month, a calculated column for month-on-month change, conditional formatting on rows over the threshold, a column chart of the top 10. She deletes the chart step because the board template has its own, approves the rest, follows the links in the response to check the new sheet and the formatted range, and opens Show Changes to confirm the source sheet was untouched.
The accountant down the hall has a trial balance exported from the practice software and no Microsoft 365 Copilot licence. The Excel Agent is the right tool there: drop the export into Microsoft 365 Copilot chat, ask for a variance summary against the prior period and a chart of the five largest movements, refine it over a couple of turns, open the result in Excel. From that point the reconciliation runs in native formulas she owns. That division is the one Frontrow recommends for every finance team: Copilot builds the structure and the narrative, and the load-bearing numbers live in auditable formulas, the position Microsoft itself took when it retired COPILOT().
What it means for an Australian business
Licensing
The two surfaces land on opposite sides of the licence boundary. The Excel Agent is explicitly available without a Microsoft 365 Copilot licence, so a Microsoft 365 Business Standard or Premium user in Copilot Chat can use it today. Plan Mode is a capability of Copilot in Excel, the in-app experience that comes with the add-on; the roadmap entry does not restate that, so confirm it in your tenant before promising it to a team. Licensing can be complex and Frontrow walks clients through exactly this boundary. For admins fielding requests, the 23 September notes added a dedicated License Requests page in the Microsoft 365 admin centre, with filters and bulk approve or deny for user-submitted Copilot licence requests.
Admin controls and data boundaries
For a CFO, the September changes are the ones to notice. Show Changes attribution lets a reviewer tell AI edits from human ones inside the workbook's own history, and the navigation links make a Copilot edit reviewable rather than a leap of faith. Python through Edit with Copilot runs under the existing security and execution controls for Python in Excel, per the 25 August note. On data, Plan Mode works on the workbook open in front of the user under that user's permissions; the Excel Agent runs inside Microsoft 365 Copilot and follows the same tenant boundary as the rest of Copilot Chat; federated connectors fetch external data at query time rather than copying it in, which is a cleaner answer for a privacy impact assessment than a synced index. Frontrow's guide to what stays in Australia under Copilot is at /insights/copilot-data-residency-au-sovereign-cloud.
Practical adoption
Plan Mode changes the kind of prompt that is safe to give: describe the whole month-end transformation and edit the plan rather than the result. Run the first few on a copy of the live workbook, keep calculations in native formulas, and have one person per team own the Show Changes review. Frontrow's tested finance prompts are at /insights/copilot-prompts-for-excel, and the tenant rollout sequence is at /insights/microsoft-365-copilot-rollout-checklist-australian-business.
What to do this month
- Confirm in your own tenant which users see Plan Mode in the Copilot pane and which see the Excel Agent in Copilot Chat; do not assume either from the licence report.
- Pick one recurring multi-step workbook task per team, run it through Plan Mode on a copy, and compare the plan against how the task is done today.
- Give the Excel Agent to the people without an add-on licence who build charts and summaries from exports, and see whether it removes the case for a licence or strengthens it.
- Add Show Changes attribution to the month-end review checklist so AI edits get a named reviewer.
- Finish the COPILOT() sweep if any preview user has not yet frozen their outputs.