The Totals Are Right. The Workbook Still Isn’t Ready to Send.

You check the formulas. The totals reconcile. The report looks ready.

Then you hide the internal pricing sheet and attach the workbook to an email.

That last step deserves another look.

A paper by Simon Thorne and Angela Collins, posted to arXiv on September 25, 2026, examines 121 documented spreadsheet incidents from 1995 to 2026. Alongside familiar calculation and data-handling errors, it highlights another problem: information that remains inside a workbook even when the recipient cannot immediately see it.

The paper discusses hidden rows, hidden sheets, cached data, and embedded objects. Its cases come from a public incident archive, not a representative sample of everyday spreadsheets. They show ways things can go wrong, rather than the odds that your next file will fail. arxiv.org

For anyone sending a workbook outside their team, the practical question is simple: what exactly are you sending?

Hidden isn’t removed

Imagine a supplier report with agreed prices on the visible sheet and your internal margins on a hidden tab. The visible report might be completely accurate. The attachment still contains information you never intended to share.

Hiding a sheet is a presentation choice with unusually ambitious career prospects.

Microsoft’s Document Inspector guidance confirms that recipients may unhide rows, columns, and worksheets. It recommends inspecting a copy because some removals cannot be undone.

In Excel for Windows, save a separate copy, then go to File > Info > Check for Issues > Inspect Document. Review the findings before removing anything. Hidden cells may feed formulas, so deleting them can change your results.

Document Inspector also has limits. Some items need manual review or removal, and it does not detect every kind of concealed content. Treat it as part of your review. Microsoft Support

Decide what the recipient actually needs

Before preparing the attachment, write down its purpose. Does the supplier need your working model, or only the agreed prices and quantities?

Build the handoff around that answer. Check the outgoing file itself, including its remaining sheets and supporting content. Reconcile the figures again after making changes.

Keep the original workbook separately so your team can still explain the calculations and trace them to their records. An accurate total answers one question.

A reviewed attachment answers another: have we included only the information this recipient should receive?