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COPILOT Function in Excel: Retired Preview, History and Workbook Migration

AI Intermediate Microsoft Excel

Understand the retired Excel COPILOT preview function, its documented rollout and retirement dates, cached results, and options for updating old workbooks.

Verification status: See the evidence and test scope described in this guide. How formula examples are checked

Retired: Microsoft removed the COPILOT worksheet function on September 14, 2026. Existing calculated results can remain as cached values, but recalculating a cell containing the function produces #NAME?. The formulas below explain old workbooks; they are not instructions for creating a currently supported AI formula. Microsoft retirement notice

Availability and version history

  • First introduced: announced August 18, 2025, as an Insider preview. Its published starting builds were Windows Version 2509, Build 19212.20000, and Mac Version 16.101, Build 25081334. The rollout required eligible preview access and a Microsoft 365 Copilot license. Original Microsoft announcement
  • Later preview scope: Microsoft’s September 2025 update documented Frontier availability on the web alongside Insider availability on Windows and Mac. September update
  • Current status and endpoint: retired September 14, 2026. Microsoft documents a date, not one final working desktop build. Do not label Excel 2024 or another perpetual edition as its last supported version.
  • Evidence checked: October 14, 2026. This is official-documentation research; no current or historical native COPILOT execution was performed.

The worksheet function’s retirement is different from the status of the broader Copilot product. Microsoft’s recommended alternative is the Copilot pane in Excel, which can perform related AI tasks. Current replacement guidance

What the historical function did

The preview let a formula combine a natural-language request with cell references. Its announced syntax was:

=COPILOT(prompt_part1, [context1], [prompt_part2], [context2], ...)

Prompt parts described the task; optional contexts supplied cells or ranges. Its output was generated text, so a precise sentence was never a dependable arithmetic-style expected result. The launch documentation is historical evidence, not a statement of current availability.

Historical example: classify fictional feedback

For interpreting an old workbook, imagine these values in A1:A3:

Feedback
The parcel arrived two days late.
The replacement fits perfectly.

A preview-era formula might have been:

=COPILOT("Label this feedback as positive, neutral or negative.",A2)

A plausible historical label would have been negative, but this is an illustrative human interpretation, not a recorded model output or a guaranteed result. Model wording and decisions could vary. After retirement, the documented recalculation outcome for the COPILOT formula is #NAME?.

That distinction matters if a screenshot shows a sensible old answer: the displayed answer may be a cached result and does not establish that the function still works.

Historical example: summarize several cells

An old worksheet could also contain:

=COPILOT("Summarize the main themes in these two comments.",A2:A3)

A reviewer might summarize the inputs as a delivery delay and a well-fitting replacement. That sentence is a manually written description of the fictional data, not an expected formula output. No deterministic expected wording is claimed.

Diagnose an old workbook carefully

  1. Work on a copy, keeping the original file and any meaningful saved outputs intact.
  2. Find formulas containing COPILOT( and note the sheet, cell, referenced range and downstream formulas that use each result.
  3. Distinguish stored text values from formulas with cached answers. A displayed sentence alone does not tell you which one you have.
  4. Record any important cached answer before experimenting with recalculation. Do not use the original workbook as a retirement test.
  5. Decide whether each result should become a reviewed fixed value, a normal deterministic formula, or a separately reviewed AI-assisted result.

A #NAME? error can have other causes elsewhere in a workbook. For a confirmed COPILOT formula, however, the official retirement notice supplies a specific explanation. Changing commas to semicolons or changing the source text does not reinstate the removed feature.

Choose a replacement by the actual task

For summarization or categorization, the Copilot pane can be considered if it is available to the account. A pane workflow is not a drop-in formula replacement: review when results are refreshed and how dependent cells are updated.

For a deterministic rule, prefer an ordinary formula. If column B contains manually reviewed labels, this example counts the negative ones:

=COUNTIF(B2:B3,"negative")

With negative in B2 and positive in B3, the independently calculated result is 1. This counts existing labels; it does not perform sentiment analysis or recreate the former AI function.

Keep an audit column explaining who reviewed an AI-generated or manually assigned label and when. Where an important decision depends on the result, check the underlying feedback rather than trusting the label alone.

Verification: Retirement behavior is attributed to Microsoft, not a native test. Preview formulas are explicitly historical; illustrative text is human-authored. The COUNTIF replacement example was independently calculated from its two supplied labels.