Claude for Excel is an Anthropic add-in that works inside Microsoft Excel. It is not a WexAI plugin. Availability, supported models and administrator approval can change, so confirm the current Anthropic and Microsoft 365 requirements before planning a team rollout.
Check access before designing the workflow
Separate three questions:
- Does your Claude plan currently include the Excel add-in?
- Does your Microsoft 365 administrator allow the add-in and required consent?
- Is the workbook data permitted for this product and task?
The Microsoft 365 connector and the Excel add-in are related surfaces but not the same thing. A connector can search approved Microsoft 365 content; the add-in works in the open workbook. Do not describe either as a generic “Claude Excel plugin” without naming the actual product.
Worked example: find a broken variance formula
Create a fictional sheet with columns Budget, Actual and Variance. Rows 2 to 5 contain numbers; row 6 is the total. The intended row formula is =C2-B2, copied down. Put =C4+B4 in row 4 as the deliberate fault.
Before asking Claude, write the expected rule and total. Then request:
Inspect this workbook for variance-formula inconsistencies.
The intended rule is Actual minus Budget for every detail row.
Do not change formatting, source values or the total row without asking.
Return the suspicious cells, current formula, expected formula and reason.
Apply a fix only after I approve the listed cells.Review the list before allowing a change. After editing, select each changed cell and confirm its formula. Recalculate the workbook, compare the total with a manual calculation, save a new version, and keep the original file.
A small workbook you can verify by hand
Create this fictional sheet. Budget is column B, Actual is column C and Variance is column D.
| Row | Budget (B) | Actual (C) | Expected variance (D) |
|---|---|---|---|
| 2 | 120 | 135 | 15 |
| 3 | 80 | 70 | -10 |
| 4 | 50 | 65 | 15 |
| 5 | 100 | 90 | -10 |
| 6 total | 350 | 360 | 10 |
Use =C2-B2 through =C5-B5; D6 should equal SUM(D2:D5), which is 10. Set D4 to =C4+B4 as the deliberate defect. It will display 115, making the wrong total 110. Ask for a proposed fix, inspect D4, and verify that the corrected total returns to 10. This is an authored teaching fixture, not a captured output from the add-in.
If Claude proposes changing B4 or C4, reject the edit: the source values were never in scope. If it proposes replacing the whole variance column with static values, reject that too. The formulas are part of the workbook’s future behavior.
Use a cell-change log
| Check | Record |
|---|---|
| Workbook version | Input filename and saved copy |
| Expected rule | Actual - Budget |
| Changed cells | Exact addresses only |
| Formula check | Old and new formulas |
| Dependency check | Any linked sheets or named ranges affected |
| Final proof | Manual total and workbook recalculation agree |
This log is the useful artifact. A fluent explanation beside the workbook does not prove that formulas, references or hidden ranges remained correct.
Add a before/after entry for each approved cell. For this fixture, the expected entry is D4: =C4+B4 → =C4-B4; a separate entry records D6: 110 → 10 after recalculation, with no formula edit to D6. The exact change log lets a reviewer tell a direct edit from a downstream effect.
Check the workbook beyond the visible cells
Before accepting a real workbook, inspect named ranges, hidden rows, filters, formulas on other sheets and external links. A correct-looking total on the visible tab does not establish that a chart or downstream report uses the intended range. Use Excel’s own formula inspection and a manual calculation for the small sample, then have the workbook owner approve the saved copy.
For a financial or regulated workbook, the example above is practice only. Use your organization’s spreadsheet controls, version history and qualified reviewer. Anthropic describes the Microsoft 365 add-ins as working across Office apps, but that product capability does not authorize a particular data transfer or financial decision.
Mistakes that break spreadsheet reviews
- Asking for “clean up” without stating what may change.
- Checking displayed values but not formulas and references.
- Overwriting the only copy of the workbook.
- Treating a visually plausible chart as proof that the source range is correct.
- Letting data move between Excel and another connected app without checking whether that transfer is allowed.
Questions about Claude for Excel
Is Claude for Excel the same as uploading an XLSX file to Claude?
No. The add-in works in Excel, while file upload or file creation happens in a Claude conversation. The available actions and review surface differ.
Can Claude change formulas directly?
Anthropic describes formula creation and editing in the Excel surface. Keep approval narrow, review exact cells and verify dependencies before saving.
Why can’t I see the add-in?
Plan access, rollout, model access and Microsoft 365 administrator settings can affect availability. Check the current official help and your tenant policy.
Can I use it for a financial decision?
Use it to assist analysis, not to replace qualified review. Material financial work needs the organization’s controls, source checks and accountable approval.
For multi-step file work outside one workbook, compare the permission model in Claude Cowork.