Sales Data Cleanup & Standardization

I have an Excel workbook packed with sales records collected from several sources and the date fields are all over the place—some are U.S. style, others European, some are stored as text, and a handful even show up as serial numbers. I need every date in every sales-related column brought into one clear, consistent format (ISO yyyy-mm-dd works well, but I’m flexible if you propose another). No other deduplication or formatting changes are required; the sole focus is correcting these date-format inconsistencies so the file is ready for reliable reporting and analysis.

You’re free to tackle the job with whatever method suits you best—straight Excel formulas, Power Query, or a quick VBA macro—as long as the end result is rock-solid and reproducible.

Deliverables:
• The cleaned Excel file with all dates standardized.
• A brief change log (or commented code, if you script it) outlining the steps you used so I can maintain the process in future updates.

I’m aiming for accuracy over speed, but a swift turnaround is appreciated. Let me know your approach and estimated timeline, and we’ll get started.