Copilot for Excel, revisited two years after I panned it
I reviewed Copilot for Excel in September 2024 and my verdict was that it was slow, that the formula suggestions missed more than they landed, and that it could not follow logic across tabs. I stand by all of that. It was the honest read at the time.
Two years is a long time in this. So I have rewritten this page against what Microsoft documents today, and the short version is that the ceiling moved a long way while the floor stayed roughly where it was.
There is also something on the calendar. The =COPILOT worksheet function ends on 14 September 2026. If you built anything on it, that is a migration with a fixed date.
Checked against Microsoft’s documentation on 29 August 2026.
The license question, which is where most people get stuck
This is the part that wastes the most time, because Copilot in Excel is not one thing you either have or do not have. Per Microsoft’s own guide to checking which Copilot license you hold, you need one of these:
- Microsoft 365 Personal or Family with an AI credits plan
- Microsoft 365 Premium
- A commercial Microsoft 365 Copilot subscription
- A Copilot Chat eligible Microsoft 365 or Office 365 business or enterprise subscription
The distinction Microsoft draws is between Copilot Premium and Copilot Basic. Premium means you hold the Microsoft 365 Copilot add-on and get priority access in Excel. Basic means you get standard access without the add-on. If Copilot feels slower for you than for the person who demoed it, that gap is usually the reason rather than anything you have configured wrong.
What it does now
The side pane is the main surface. You ask in plain English and it works on the sheet: generating data, applying formulas across multiple sheets, summarizing, creating and editing charts and PivotTables with editable links back to the source, and answering questions about your data as trends or outliers.
The cross-sheet part is the real change from 2024. My original complaint was that it could not associate work across tables or tabs. Microsoft now documents formulas applied across multiple sheets, which is the thing that made it useless for a real model.
Agent Mode is the part worth your attention
If you only look at one thing, look at this rather than the side pane.
Agent Mode in Excel is generally available on Windows, with Mac rolling out, having started on Excel for the web. Rather than answering a question about the sheet, it works through a multi-step task on the sheet: building a workbook, repairing formulas, running a web-grounded search to fill something in.
It also carries a model picker, and this is the detail I did not expect. You can choose between OpenAI’s GPT-5.2 and Anthropic’s Claude Opus 4.5 inside Excel, on Microsoft 365 Copilot and Microsoft 365 Premium licenses. If you have read my write-up of Claude for Excel, that is the same model, reached through Microsoft’s add-in instead of Anthropic’s.
Agent Mode needs Microsoft 365 Personal, Family or Premium, or a commercial Microsoft 365 Copilot license. There is a fuller walkthrough on Agent Mode in Excel.
Whichever tool you land on
The Excel prompts I run on real finance work
Finance-specific prompts for formulas, cleanup and reporting that work in Copilot, Claude or ChatGPT, plus the templates that pair with them. Free.
The =COPILOT function ends on 14 September 2026
Microsoft shipped a worksheet function called =COPILOT in August 2025, so you could call the model from a cell like any other formula. Microsoft switches it off on 14 September 2026.
The Microsoft 365 message center notice, MC1454373, published 13 August 2026, says that from 14 September 2026 the function will no longer be available. It affects anyone on the Excel Insider and Frontier preview programmes who was using it. Microsoft never took it to general availability, so it reached the end of its life still in preview.
Microsoft’s guidance is to move to the Copilot side pane, which covers summarizing, classifying, generating content and pulling information from the web. What it does not give you back is the thing that made the function interesting, which was a live result sitting in a cell that recalculated with the rest of the model.
If you are the person in your team who built something on it, the useful move this week is to search your workbooks for COPILOT( before someone opens a file in a fortnight and finds a column of errors.
What still trips it up
Two constraints from Microsoft’s own FAQ that I had not seen written up anywhere, and the first one will catch finance teams specifically.
Your workbook has to be on automatic calculation
Copilot editing is only supported when Calculation Options are set to Automatic. Plenty of large finance models run on Manual precisely so they do not recalculate every time you touch a cell. If that is you, Copilot editing will not work and nothing will tell you why.
Everyone with the file sees what it changed
When you save Copilot’s changes, anyone with access to the workbook can see them. Fine for a working file, worth thinking about on anything sensitive that circulates before review.
There is also a file-format trap: Strict Open XML Spreadsheet is not supported, so save as a normal .xlsx. And a checked-out SharePoint file will throw an unsupported file state error until you check it back in. Microsoft’s Copilot in Excel FAQ has the full list.
My verdict now
In 2024 I said the concept was good and the execution was not there. That has narrowed, but the reason has less to do with the side pane than with Agent Mode and the model behind it.
If you have a Microsoft 365 Copilot license already, Agent Mode is worth an hour on a real workbook, and the model picker means you are no longer stuck with whichever engine Microsoft happened to ship. If you are choosing what to pay for from scratch, that is a genuine comparison rather than an obvious one, and I have run it head to head in Claude for Excel versus Copilot.
The thing I would not do is build a workflow on a preview feature again. The =COPILOT function is the second time in two years that something I was tempted to teach got pulled before it shipped properly.
Where to go next
AI in Excel is the hub this page sits under and covers the whole field tool by tool, including which license each route needs. For the head-to-head versions, there is ChatGPT against Claude against Copilot on the same tasks.
If your reason for looking at Copilot is that a monthly process keeps eating your week, finance automation is the better starting point, and Office Scripts handles the repeatable pieces Copilot will not touch.
