Microsoft to Kill Excel's COPILOT() Function on September 14, 2026

Microsoft will retire Excel's COPILOT() function on September 14, 2026, barely a year after the feature debuted in preview. The company has scrapped plans to make the function generally available in 2027.

Microsoft introduced COPILOT() in August 2025, first for Beta Channel users with a Microsoft 365 Copilot license, then for Excel for the web users through the Frontier program. The function let users type instructions directly into a worksheet cell to summon the AI assistant, rather than switching to a separate pane.

That convenience is now going away. Microsoft has updated its Microsoft 365 roadmap with a blunt notice: "We have decided not to move forward with this feature. We apologize for the inconvenience." A Microsoft 365 Message Center post frames the move as consolidation: "This change helps streamline the Copilot experience within Excel while continuing to provide AI assistance through a supported interface."

According to Microsoft, the Copilot side pane already covers most of what the in-cell function did, including summarizing text, classifying data, generating content, and retrieving information from the web. The company's position is that maintaining two separate entry points to the same AI capabilities added complexity without adding value.

What existing users need to do

Because COPILOT() never left preview status, Microsoft had already warned against using it in production spreadsheets. Its original announcement cautioned that "output should be reviewed and validated for accuracy, especially for critical business decisions or reports" — a disclaimer that sits awkwardly with spreadsheet users who depend on exact numbers.

Anyone who built formulas around the function anyway now has until September 14, 2026 to replace them, likely by shifting those workflows into the Copilot side pane manually.

Part of a broader Copilot cleanup

The retirement fits a pattern of Microsoft adjusting Copilot's presence across its productivity suite in response to user feedback. The company recently let users banish the floating Dynamic Action Button to the toolbar instead of leaving it hovering over content, and it has pushed Copilot more aggressively into Classic Outlook. Rivals have also moved into the spreadsheet AI space: xAI's Grok recently launched an Excel add-in of its own.

Google, meanwhile, still offers a comparable in-cell AI function in Sheets, announced in June 2025 and, as far as reporting shows, still active.

What this means

This is a product-packaging decision, not a capability cut — the underlying AI assistance Microsoft sells through Copilot in Excel remains available via the side pane. But the reversal signals that Microsoft misjudged demand or maintenance cost for a dedicated worksheet function during its yearlong preview, canceling planned general availability rather than shipping it. For enterprise Excel users, the lesson is familiar: preview-labeled AI features from any vendor can disappear before reaching GA, so building dependent workflows on them carries real risk. Google's continued support for an equivalent Sheets function, if it holds, could become a differentiator worth watching.